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19622198 | What does 'set -e' mean in a Bash script? | 1,195 | 2013-10-27 19:06:32 | <p>I'm studying the content of this <code>preinst</code> file that the script executes before that package is unpacked from its <a href="https://en.wikipedia.org/wiki/Debian" rel="noreferrer">Debian</a> archive (<code>.deb</code>) file.</p>
<p>The script has the following code:</p>
<pre><code>#!/bin/bash
set -e
# Autom... | 808,651 | 1,833,945 | 2026-01-18 23:31:21 | 19,622,569 | 1,214 | 2013-10-27 19:39:10 | 465,183 | 2026-01-18 23:31:21 | https://stackoverflow.com/q/19622198 | https://stackoverflow.com/a/19622569 | <p>From <code>help set</code> and <a href="https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html#index-set" rel="nofollow noreferrer"><em>Bash Reference Documentation: The Set Builtin</em></a>:</p>
<blockquote>
<p><code>-e Exit immediately if a command exits with a non-zero status.</code></p>
</block... | <p>From <code>help set</code> and <a href="https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html#index-set" rel="nofollow noreferrer"><em>Bash Reference Documentation: The Set Builtin</em></a>:</p> <blockquote> <p><code>-e Exit immediately if a command exits with a non-zero status.</code></p> </block... | 58, 387, 390, 10327 | bash, linux, sh, shell | <h1>What does 'set -e' mean in a Bash script?</h1>
<p>I'm studying the content of this <code>preinst</code> file that the script executes before that package is unpacked from its <a href="https://en.wikipedia.org/wiki/Debian" rel="noreferrer">Debian</a> archive (<code>.deb</code>) file.</p>
<p>The script has the follow... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 116 | bash | # What does 'set -e' mean in a Bash script?
I'm studying the content of this `preinst` file that the script executes before that package is unpacked from its [Debian](https://en.wikipedia.org/wiki/Debian) archive (`.deb`) file.
The script has the following code:
```
#!/bin/bash
set -e
# Automatically added by dh_ins... | From `help set` and [*Bash Reference Documentation: The Set Builtin*](https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html#index-set):
> `-e Exit immediately if a command exits with a non-zero status.`
But it's considered bad practice by some (Bash FAQ and [IRC](https://en.wikipedia.org/wiki/Intern... |
2157554 | How to handle command-line arguments in PowerShell | 658 | 2010-01-28 20:01:10 | <p>What is the "best" way to handle command-line arguments?</p>
<p>It seems like there are several answers on what the "best" way is and as a result I am stuck on how to handle something as simple as:</p>
<pre><code>script.ps1 /n name /d domain
</code></pre>
<p>AND</p>
<pre><code>script.ps1 /d domain /n name.
</cod... | 984,179 | 261,317 | 2024-08-20 11:04:35 | 2,157,625 | 1,213 | 2010-01-28 20:13:40 | 239,599 | 2022-04-22 17:47:56 | https://stackoverflow.com/q/2157554 | https://stackoverflow.com/a/2157625 | <p>You are reinventing the wheel. Normal PowerShell scripts have parameters starting with <code>-</code>, like <code>script.ps1 -server http://devserver</code></p>
<p>Then you handle them in a <code>param</code> section (note that this <strong>must</strong> begin at the first non-commented line in your script).</p>
<p>... | <p>You are reinventing the wheel. Normal PowerShell scripts have parameters starting with <code>-</code>, like <code>script.ps1 -server http://devserver</code></p> <p>Then you handle them in a <code>param</code> section (note that this <strong>must</strong> begin at the first non-commented line in your script).</p> <p>... | 526, 31134 | command-line-arguments, powershell | <h1>How to handle command-line arguments in PowerShell</h1>
<p>What is the "best" way to handle command-line arguments?</p>
<p>It seems like there are several answers on what the "best" way is and as a result I am stuck on how to handle something as simple as:</p>
<pre><code>script.ps1 /n name /d domain
</code></pre>... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 117 | bash | # How to handle command-line arguments in PowerShell
What is the "best" way to handle command-line arguments?
It seems like there are several answers on what the "best" way is and as a result I am stuck on how to handle something as simple as:
```
script.ps1 /n name /d domain
```
AND
```
script.ps1 /d domain /n na... | You are reinventing the wheel. Normal PowerShell scripts have parameters starting with `-`, like `script.ps1 -server http://devserver`
Then you handle them in a `param` section (note that this **must** begin at the first non-commented line in your script).
You can also assign default values to your params, read them ... |
22727107 | How to find the last field using 'cut' | 575 | 2014-03-29 04:43:37 | <p><em>Without</em> using <code>sed</code> or <code>awk</code>, <em>only</em> <code>cut</code>, how do I get the last field when the number of fields are unknown or change with every line?</p>
| 508,886 | 3,262,003 | 2024-10-19 14:50:01 | 22,727,211 | 1,211 | 2014-03-29 04:58:11 | 2,554,537 | 2020-02-06 21:02:43 | https://stackoverflow.com/q/22727107 | https://stackoverflow.com/a/22727211 | <p>You could try something like this:</p>
<pre><code>echo 'maps.google.com' | rev | cut -d'.' -f 1 | rev
</code></pre>
<p><strong>Explanation</strong></p>
<ul>
<li><code>rev</code> reverses "maps.google.com" to be <code>moc.elgoog.spam</code></li>
<li><code>cut</code> uses dot (ie '.') as the delimiter, and chooses ... | <p>You could try something like this:</p> <pre><code>echo 'maps.google.com' | rev | cut -d'.' -f 1 | rev </code></pre> <p><strong>Explanation</strong></p> <ul> <li><code>rev</code> reverses "maps.google.com" to be <code>moc.elgoog.spam</code></li> <li><code>cut</code> uses dot (ie '.') as the delimiter, and chooses ... | 58, 387, 4257 | bash, cut, linux | <h1>How to find the last field using 'cut'</h1>
<p><em>Without</em> using <code>sed</code> or <code>awk</code>, <em>only</em> <code>cut</code>, how do I get the last field when the number of fields are unknown or change with every line?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 118 | bash | # How to find the last field using 'cut'
*Without* using `sed` or `awk`, *only* `cut`, how do I get the last field when the number of fields are unknown or change with every line? | You could try something like this:
```
echo 'maps.google.com' | rev | cut -d'.' -f 1 | rev
```
**Explanation**
- `rev` reverses "maps.google.com" to be `moc.elgoog.spam`
- `cut` uses dot (ie '.') as the delimiter, and chooses the first field, which is `moc`
- lastly, we reverse it again to get `com` |
806906 | How do I test if a variable is a number in Bash? | 931 | 2009-04-30 13:30:16 | <p>I just can't figure out how do I make sure an argument passed to my script is a number or not.</p>
<p>All I want to do is something like this:</p>
<pre><code>test *isnumber* $1 && VAR=$1 || echo "need a number"
</code></pre>
<p>Any help?</p>
| 1,121,549 | 802 | 2025-12-30 15:05:10 | 806,923 | 1,199 | 2009-04-30 13:32:20 | 14,122 | 2018-08-26 00:40:36 | https://stackoverflow.com/q/806906 | https://stackoverflow.com/a/806923 | <p>One approach is to use a regular expression, like so:</p>
<pre><code>re='^[0-9]+$'
if ! [[ $yournumber =~ $re ]] ; then
echo "error: Not a number" >&2; exit 1
fi
</code></pre>
<p>If the value is not necessarily an integer, consider amending the regex appropriately; for instance:</p>
<pre><code>^[0-9]+([... | <p>One approach is to use a regular expression, like so:</p> <pre><code>re='^[0-9]+$' if ! [[ $yournumber =~ $re ]] ; then echo "error: Not a number" >&2; exit 1 fi </code></pre> <p>If the value is not necessarily an integer, consider amending the regex appropriately; for instance:</p> <pre><code>^[0-9]+([... | 387, 390 | bash, shell | <h1>How do I test if a variable is a number in Bash?</h1>
<p>I just can't figure out how do I make sure an argument passed to my script is a number or not.</p>
<p>All I want to do is something like this:</p>
<pre><code>test *isnumber* $1 && VAR=$1 || echo "need a number"
</code></pre>
<p>Any help?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 119 | bash | # How do I test if a variable is a number in Bash?
I just can't figure out how do I make sure an argument passed to my script is a number or not.
All I want to do is something like this:
```
test *isnumber* $1 && VAR=$1 || echo "need a number"
```
Any help? | One approach is to use a regular expression, like so:
```
re='^[0-9]+$'
if ! [[ $yournumber =~ $re ]] ; then
echo "error: Not a number" >&2; exit 1
fi
```
If the value is not necessarily an integer, consider amending the regex appropriately; for instance:
```
^[0-9]+([.][0-9]+)?$
```
...or, to handle numbers wit... |
2016894 | How can I split a large text file into smaller files with an equal number of lines? | 773 | 2010-01-06 22:40:39 | <p>I've got a large (by number of lines) plain text file that I'd like to split into smaller files, also by number of lines. So if my file has around 2M lines, I'd like to split it up into 10 files that contain 200k lines, or 100 files that contain 20k lines (plus one file with the remainder; being evenly divisible do... | 843,493 | 217,332 | 2025-05-20 03:15:31 | 2,016,918 | 1,191 | 2010-01-06 22:44:37 | 61,974 | 2024-12-22 18:35:27 | https://stackoverflow.com/q/2016894 | https://stackoverflow.com/a/2016918 | <p>Have a look at the <a href="https://www.gnu.org/software/coreutils/manual/html_node/split-invocation.html" rel="noreferrer">split command</a>:</p>
<p>For version: <code>(GNU coreutils) 8.32</code></p>
<pre class="lang-none prettyprint-override"><code>$ split --help
Usage: split [OPTION]... [FILE [PREFIX]]
Output pie... | <p>Have a look at the <a href="https://www.gnu.org/software/coreutils/manual/html_node/split-invocation.html" rel="noreferrer">split command</a>:</p> <p>For version: <code>(GNU coreutils) 8.32</code></p> <pre class="lang-none prettyprint-override"><code>$ split --help Usage: split [OPTION]... [FILE [PREFIX]] Output pie... | 34, 387, 5310 | bash, file, unix | <h1>How can I split a large text file into smaller files with an equal number of lines?</h1>
<p>I've got a large (by number of lines) plain text file that I'd like to split into smaller files, also by number of lines. So if my file has around 2M lines, I'd like to split it up into 10 files that contain 200k lines, or ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 120 | bash | # How can I split a large text file into smaller files with an equal number of lines?
I've got a large (by number of lines) plain text file that I'd like to split into smaller files, also by number of lines. So if my file has around 2M lines, I'd like to split it up into 10 files that contain 200k lines, or 100 files ... | Have a look at the [split command](https://www.gnu.org/software/coreutils/manual/html_node/split-invocation.html):
For version: `(GNU coreutils) 8.32`
```
$ split --help
Usage: split [OPTION]... [FILE [PREFIX]]
Output pieces of FILE to PREFIXaa, PREFIXab, ...;
default size is 1000 lines, and default PREFIX is 'x'.
W... |
4565700 | How to specify the private SSH-key to use when executing shell command on Git? | 1,916 | 2010-12-30 19:42:01 | <p>A rather unusual situation perhaps, but I want to specify a private SSH-key to use when executing a shell (<code>git</code>) command from the local computer.</p>
<p>Basically like this:</p>
<pre><code>git clone git@github.com:TheUser/TheProject.git -key "/home/christoffer/ssh_keys/theuser"
</code></pre>
<p... | 2,260,713 | 160,574 | 2025-06-29 09:49:17 | 4,565,746 | 1,179 | 2010-12-30 19:48:28 | 33,006 | 2016-11-22 20:42:26 | https://stackoverflow.com/q/4565700 | https://stackoverflow.com/a/4565746 | <p>Something like this should work (suggested by orip):</p>
<pre><code>ssh-agent bash -c 'ssh-add /somewhere/yourkey; git clone git@github.com:user/project.git'
</code></pre>
<p>if you prefer subshells, you could try the following (though it is more fragile):</p>
<pre><code>ssh-agent $(ssh-add /somewhere/yourkey; gi... | <p>Something like this should work (suggested by orip):</p> <pre><code>ssh-agent bash -c 'ssh-add /somewhere/yourkey; git clone git@github.com:user/project.git' </code></pre> <p>if you prefer subshells, you could try the following (though it is more fragile):</p> <pre><code>ssh-agent $(ssh-add /somewhere/yourkey; gi... | 119, 386, 387, 390 | bash, git, shell, ssh | <h1>How to specify the private SSH-key to use when executing shell command on Git?</h1>
<p>A rather unusual situation perhaps, but I want to specify a private SSH-key to use when executing a shell (<code>git</code>) command from the local computer.</p>
<p>Basically like this:</p>
<pre><code>git clone git@github.com:The... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 121 | bash | # How to specify the private SSH-key to use when executing shell command on Git?
A rather unusual situation perhaps, but I want to specify a private SSH-key to use when executing a shell (`git`) command from the local computer.
Basically like this:
```
git clone git@github.com:TheUser/TheProject.git -key "/home/chri... | Something like this should work (suggested by orip):
```
ssh-agent bash -c 'ssh-add /somewhere/yourkey; git clone git@github.com:user/project.git'
```
if you prefer subshells, you could try the following (though it is more fragile):
```
ssh-agent $(ssh-add /somewhere/yourkey; git clone git@github.com:user/project.gi... |
20796200 | How to loop over files in directory and change path and add suffix to filename | 883 | 2013-12-27 06:49:34 | <p>I need to write a script that starts my program with different arguments. I start my program with:</p>
<p><code>./MyProgram.exe Data/data1.txt [Logs/data1_Log.txt]</code>.</p>
<p>Here is the pseudocode for what I want to do:</p>
<pre class="lang-bash prettyprint-override"><code>for each filename in /Data do
for in... | 1,476,105 | 2,918,918 | 2025-07-09 14:52:44 | 20,796,617 | 1,178 | 2013-12-27 07:23:33 | 89,817 | 2021-10-17 00:50:34 | https://stackoverflow.com/q/20796200 | https://stackoverflow.com/a/20796617 | <p>A couple of notes first: when you use <code>Data/data1.txt</code> as an argument, should it really be <code>/Data/data1.txt</code> (with a leading slash)? Also, should the outer loop scan only for .txt files, or all files in /Data? Here's an answer, assuming <code>/Data/data1.txt</code> and .txt files only:</p>
<pre... | <p>A couple of notes first: when you use <code>Data/data1.txt</code> as an argument, should it really be <code>/Data/data1.txt</code> (with a leading slash)? Also, should the outer loop scan only for .txt files, or all files in /Data? Here's an answer, assuming <code>/Data/data1.txt</code> and .txt files only:</p> <pre... | 387, 1062, 2531, 3889 | bash, filenames, for-loop, glob | <h1>How to loop over files in directory and change path and add suffix to filename</h1>
<p>I need to write a script that starts my program with different arguments. I start my program with:</p>
<p><code>./MyProgram.exe Data/data1.txt [Logs/data1_Log.txt]</code>.</p>
<p>Here is the pseudocode for what I want to do:</p>
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 122 | bash | # How to loop over files in directory and change path and add suffix to filename
I need to write a script that starts my program with different arguments. I start my program with:
`./MyProgram.exe Data/data1.txt [Logs/data1_Log.txt]`.
Here is the pseudocode for what I want to do:
```
for each filename in /Data do
... | A couple of notes first: when you use `Data/data1.txt` as an argument, should it really be `/Data/data1.txt` (with a leading slash)? Also, should the outer loop scan only for .txt files, or all files in /Data? Here's an answer, assuming `/Data/data1.txt` and .txt files only:
```
#!/bin/bash
for filename in /Data/*.txt... |
1378274 | In a Bash script, how can I exit the entire script if a certain condition occurs? | 1,003 | 2009-09-04 09:51:52 | <p>I'm writing a script in Bash to test some code. However, it seems silly to run the tests if compiling the code fails in the first place, in which case I'll just abort the tests.</p>
<p>Is there a way I can do this without wrapping the entire script inside of a while loop and using breaks? Something like a <strong>d... | 1,156,716 | 39,036 | 2024-07-15 09:22:36 | 1,378,284 | 1,171 | 2009-09-04 09:53:53 | 149,530 | 2024-07-15 09:22:36 | https://stackoverflow.com/q/1378274 | https://stackoverflow.com/a/1378284 | <p>Try this statement:</p>
<pre><code>exit 1
</code></pre>
<p>Replace <code>1</code> with appropriate error codes. See also <a href="/questions/1101957/are-there-any-standard-exit-status-codes-in-linux">Exit Codes With Special Meanings</a>.</p>
| <p>Try this statement:</p> <pre><code>exit 1 </code></pre> <p>Replace <code>1</code> with appropriate error codes. See also <a href="/questions/1101957/are-there-any-standard-exit-status-codes-in-linux">Exit Codes With Special Meanings</a>.</p> | 387, 531, 10021, 10871 | bash, exit, exit-code, scripting | <h1>In a Bash script, how can I exit the entire script if a certain condition occurs?</h1>
<p>I'm writing a script in Bash to test some code. However, it seems silly to run the tests if compiling the code fails in the first place, in which case I'll just abort the tests.</p>
<p>Is there a way I can do this without wra... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 123 | bash | # In a Bash script, how can I exit the entire script if a certain condition occurs?
I'm writing a script in Bash to test some code. However, it seems silly to run the tests if compiling the code fails in the first place, in which case I'll just abort the tests.
Is there a way I can do this without wrapping the entire... | Try this statement:
```
exit 1
```
Replace `1` with appropriate error codes. See also [Exit Codes With Special Meanings](/questions/1101957/are-there-any-standard-exit-status-codes-in-linux). |
6022384 | Bash tool to get nth line from a file | 910 | 2011-05-16 19:33:42 | <p>Is there a "canonical" way of doing that? I've been using <code>head -n | tail -1</code> which does the trick, but I've been wondering if there's a Bash tool that specifically extracts a line (or a range of lines) from a file.</p>
<p>By "canonical" I mean a program whose main function is doing that.</p>
| 764,927 | 754,336 | 2025-07-29 13:56:39 | 6,022,431 | 1,168 | 2011-05-16 19:38:33 | 548,225 | 2025-07-28 20:51:04 | https://stackoverflow.com/q/6022384 | https://stackoverflow.com/a/6022431 | <p><code>head</code> and pipe with <code>tail</code> will be slow for a huge file. I would suggest <code>sed</code> like this:</p>
<pre><code>sed 'NUMq;d' file
</code></pre>
<p>Where <code>NUM</code> is the number of the line you want to print; so, for example, <code>sed '10q;d' file</code> to print the 10th line of <c... | <p><code>head</code> and pipe with <code>tail</code> will be slow for a huge file. I would suggest <code>sed</code> like this:</p> <pre><code>sed 'NUMq;d' file </code></pre> <p>Where <code>NUM</code> is the number of the line you want to print; so, for example, <code>sed '10q;d' file</code> to print the 10th line of <c... | 34, 387, 390, 990, 5282 | awk, bash, sed, shell, unix | <h1>Bash tool to get nth line from a file</h1>
<p>Is there a "canonical" way of doing that? I've been using <code>head -n | tail -1</code> which does the trick, but I've been wondering if there's a Bash tool that specifically extracts a line (or a range of lines) from a file.</p>
<p>By "canonical" I mean a program who... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 124 | bash | # Bash tool to get nth line from a file
Is there a "canonical" way of doing that? I've been using `head -n | tail -1` which does the trick, but I've been wondering if there's a Bash tool that specifically extracts a line (or a range of lines) from a file.
By "canonical" I mean a program whose main function is doing t... | `head` and pipe with `tail` will be slow for a huge file. I would suggest `sed` like this:
```
sed 'NUMq;d' file
```
Where `NUM` is the number of the line you want to print; so, for example, `sed '10q;d' file` to print the 10th line of `file`.
Explanation:
`NUMq` will quit immediately when the line number is `NUM`.... |
8748831 | When do we need curly braces around shell variables? | 1,034 | 2012-01-05 19:54:03 | <p>In shell scripts, when do we use <code>{}</code> when expanding variables?</p>
<p>For example, I have seen the following:</p>
<pre><code>var=10 # Declare variable
echo "${var}" # One use of the variable
echo "$var" # Another use of the variable
</code></pre>
<p>Is there a significant difference, or is i... | 428,212 | 1,066,402 | 2025-02-09 15:51:07 | 8,748,880 | 1,164 | 2012-01-05 19:56:34 | 166,749 | 2025-02-09 15:51:07 | https://stackoverflow.com/q/8748831 | https://stackoverflow.com/a/8748880 | <p>In your particular example, it makes no difference. However, the <code>{}</code> in <code>${}</code> are useful if you want to expand the variable <code>foo</code> in the string</p>
<pre><code>"${foo}bar"
</code></pre>
<p>since <code>"$foobar"</code> would instead expand the variable identified b... | <p>In your particular example, it makes no difference. However, the <code>{}</code> in <code>${}</code> are useful if you want to expand the variable <code>foo</code> in the string</p> <pre><code>"${foo}bar" </code></pre> <p>since <code>"$foobar"</code> would instead expand the variable identified b... | 367, 387, 390, 14116, 19749 | bash, curly-braces, shell, syntax, variable-expansion | <h1>When do we need curly braces around shell variables?</h1>
<p>In shell scripts, when do we use <code>{}</code> when expanding variables?</p>
<p>For example, I have seen the following:</p>
<pre><code>var=10 # Declare variable
echo "${var}" # One use of the variable
echo "$var" # Another use of the variabl... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 125 | bash | # When do we need curly braces around shell variables?
In shell scripts, when do we use `{}` when expanding variables?
For example, I have seen the following:
```
var=10 # Declare variable
echo "${var}" # One use of the variable
echo "$var" # Another use of the variable
```
Is there a significant differen... | In your particular example, it makes no difference. However, the `{}` in `${}` are useful if you want to expand the variable `foo` in the string
```
"${foo}bar"
```
since `"$foobar"` would instead expand the variable identified by `foobar`.
Curly braces are also unconditionally required when:
- expanding array elem... |
84882 | sudo echo "something" >> /etc/privilegedFile doesn't work | 754 | 2008-09-17 16:09:00 | <p>This is a pretty simple question, at least it seems like it should be, about sudo permissions in Linux.</p>
<p>There are a lot of times when I just want to append something to <code>/etc/hosts</code> or a similar file but end up not being able to because both <code>></code> and <code>>></code> are not allo... | 337,876 | 9,908 | 2020-09-24 14:41:48 | 550,808 | 1,160 | 2009-02-15 12:34:20 | 37,664 | 2019-08-12 14:49:09 | https://stackoverflow.com/q/84882 | https://stackoverflow.com/a/550808 | <p>Use <code>tee --append</code> or <code>tee -a</code>.</p>
<pre><code>echo 'deb blah ... blah' | sudo tee -a /etc/apt/sources.list
</code></pre>
<p>Make sure to avoid quotes inside quotes.</p>
<p>To avoid printing data back to the console, redirect the output to /dev/null.</p>
<pre><code>echo 'deb blah ... blah' ... | <p>Use <code>tee --append</code> or <code>tee -a</code>.</p> <pre><code>echo 'deb blah ... blah' | sudo tee -a /etc/apt/sources.list </code></pre> <p>Make sure to avoid quotes inside quotes.</p> <p>To avoid printing data back to the console, redirect the output to /dev/null.</p> <pre><code>echo 'deb blah ... blah' ... | 359, 387, 390, 531, 1674 | bash, permissions, scripting, shell, sudo | <h1>sudo echo "something" >> /etc/privilegedFile doesn't work</h1>
<p>This is a pretty simple question, at least it seems like it should be, about sudo permissions in Linux.</p>
<p>There are a lot of times when I just want to append something to <code>/etc/hosts</code> or a similar file but end up not being able to be... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 126 | bash | # sudo echo "something" >> /etc/privilegedFile doesn't work
This is a pretty simple question, at least it seems like it should be, about sudo permissions in Linux.
There are a lot of times when I just want to append something to `/etc/hosts` or a similar file but end up not being able to because both `>` and `>>` are... | Use `tee --append` or `tee -a`.
```
echo 'deb blah ... blah' | sudo tee -a /etc/apt/sources.list
```
Make sure to avoid quotes inside quotes.
To avoid printing data back to the console, redirect the output to /dev/null.
```
echo 'deb blah ... blah' | sudo tee -a /etc/apt/sources.list > /dev/null
```
Remember about... |
733824 | How can I run a shell script on a Unix console or Mac terminal? | 625 | 2009-04-09 11:36:26 | <p>How can I run a shell script on a Unix console or Mac terminal?</p>
<p>I know it, forget it and relearn it again. It is time to write it down.</p>
| 1,247,834 | 4,975 | 2025-11-27 18:22:41 | 733,901 | 1,138 | 2009-04-09 11:58:50 | 58,803 | 2025-11-27 18:22:41 | https://stackoverflow.com/q/733824 | https://stackoverflow.com/a/733901 | <p>To run a non-executable <a href="https://en.wikipedia.org/wiki/Bourne_shell" rel="nofollow noreferrer">Bourne shell</a> (executable <code>sh</code>) script, use:</p>
<pre class="lang-none prettyprint-override"><code>sh myscript
</code></pre>
<p>To run a non-executable Bash script, use:</p>
<pre class="lang-none pret... | <p>To run a non-executable <a href="https://en.wikipedia.org/wiki/Bourne_shell" rel="nofollow noreferrer">Bourne shell</a> (executable <code>sh</code>) script, use:</p> <pre class="lang-none prettyprint-override"><code>sh myscript </code></pre> <p>To run a non-executable Bash script, use:</p> <pre class="lang-none pret... | 34, 58, 369, 387, 390 | bash, linux, macos, shell, unix | <h1>How can I run a shell script on a Unix console or Mac terminal?</h1>
<p>How can I run a shell script on a Unix console or Mac terminal?</p>
<p>I know it, forget it and relearn it again. It is time to write it down.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 127 | bash | # How can I run a shell script on a Unix console or Mac terminal?
How can I run a shell script on a Unix console or Mac terminal?
I know it, forget it and relearn it again. It is time to write it down. | To run a non-executable [Bourne shell](https://en.wikipedia.org/wiki/Bourne_shell) (executable `sh`) script, use:
```
sh myscript
```
To run a non-executable Bash script, use:
```
bash myscript
```
To start an executable (which is any file with executable permission); you just specify it by its path:
```
/foo/bar
... |
3096259 | Bash command to sum a column of numbers | 516 | 2010-06-22 18:58:59 | <p>I want a bash command that I can pipe into that will sum a column of numbers. I just want a quick one liner that will do something essentially like this:</p>
<pre><code>cat FileWithColumnOfNumbers.txt | sum
</code></pre>
| 450,235 | 54,777 | 2025-10-11 13:13:47 | 3,096,575 | 1,133 | 2010-06-22 19:47:56 | 430,749 | 2021-04-30 15:40:21 | https://stackoverflow.com/q/3096259 | https://stackoverflow.com/a/3096575 | <h1>Using existing file:</h1>
<pre><code>paste -sd+ infile | bc
</code></pre>
<h1>Using stdin:</h1>
<pre><code><cmd> | paste -sd+ | bc
</code></pre>
<p>Edit:
With some <em>paste</em> implementations you need to be more explicit when reading from <em>stdin</em>:</p>
<p><code><cmd> | paste -sd+ - | bc</code><... | <h1>Using existing file:</h1> <pre><code>paste -sd+ infile | bc </code></pre> <h1>Using stdin:</h1> <pre><code><cmd> | paste -sd+ | bc </code></pre> <p>Edit: With some <em>paste</em> implementations you need to be more explicit when reading from <em>stdin</em>:</p> <p><code><cmd> | paste -sd+ - | bc</code><... | 387 | bash | <h1>Bash command to sum a column of numbers</h1>
<p>I want a bash command that I can pipe into that will sum a column of numbers. I just want a quick one liner that will do something essentially like this:</p>
<pre><code>cat FileWithColumnOfNumbers.txt | sum
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 128 | bash | # Bash command to sum a column of numbers
I want a bash command that I can pipe into that will sum a column of numbers. I just want a quick one liner that will do something essentially like this:
```
cat FileWithColumnOfNumbers.txt | sum
``` | # Using existing file:
```
paste -sd+ infile | bc
```
# Using stdin:
```
<cmd> | paste -sd+ | bc
```
Edit:
With some *paste* implementations you need to be more explicit when reading from *stdin*:
`<cmd> | paste -sd+ - | bc`
**Options used**:
> -s (serial) - merges all the lines into a single line
>
> -d - use a... |
9332802 | How to write a bash script that takes optional input arguments? | 796 | 2012-02-17 17:32:52 | <p>I want my script to be able to take an optional input, </p>
<p>e.g. currently my script is </p>
<pre><code>#!/bin/bash
somecommand foo
</code></pre>
<p>but I would like it to say:</p>
<pre><code>#!/bin/bash
somecommand [ if $1 exists, $1, else, foo ]
</code></pre>
| 528,275 | 513,006 | 2024-10-25 19:20:26 | 9,333,006 | 1,125 | 2012-02-17 17:50:19 | 561,879 | 2015-01-31 20:45:53 | https://stackoverflow.com/q/9332802 | https://stackoverflow.com/a/9333006 | <p>You could use the default-value syntax:</p>
<pre><code>somecommand ${1:-foo}
</code></pre>
<p>The above will, as described in <a href="http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion" rel="noreferrer">Bash Reference Manual - 3.5.3 Shell Parameter Expansion</a> [emphasis mine]:</p>
<... | <p>You could use the default-value syntax:</p> <pre><code>somecommand ${1:-foo} </code></pre> <p>The above will, as described in <a href="http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion" rel="noreferrer">Bash Reference Manual - 3.5.3 Shell Parameter Expansion</a> [emphasis mine]:</p> <... | 387, 2313, 10355 | arguments, bash, parameter-passing | <h1>How to write a bash script that takes optional input arguments?</h1>
<p>I want my script to be able to take an optional input, </p>
<p>e.g. currently my script is </p>
<pre><code>#!/bin/bash
somecommand foo
</code></pre>
<p>but I would like it to say:</p>
<pre><code>#!/bin/bash
somecommand [ if $1 exists, $1, ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 129 | bash | # How to write a bash script that takes optional input arguments?
I want my script to be able to take an optional input,
e.g. currently my script is
```
#!/bin/bash
somecommand foo
```
but I would like it to say:
```
#!/bin/bash
somecommand [ if $1 exists, $1, else, foo ]
``` | You could use the default-value syntax:
```
somecommand ${1:-foo}
```
The above will, as described in [Bash Reference Manual - 3.5.3 Shell Parameter Expansion](http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion) [emphasis mine]:
> If parameter is unset *or null*, the expansion of word is ... |
2035193 | How to run a PowerShell script | 1,105 | 2010-01-09 22:19:10 | <p>How do I run a PowerShell script?</p>
<ul>
<li>I have a script named myscript.ps1</li>
<li>I have all the necessary frameworks installed</li>
<li>I set that <a href="https://stackoverflow.com/questions/10635/why-dont-my-powershell-scripts-run">execution policy</a> thing</li>
<li>I have followed the instructions on ... | 3,609,787 | 187,606 | 2025-04-26 19:27:11 | 2,035,209 | 1,113 | 2010-01-09 22:24:43 | 13,302 | 2022-03-31 17:59:23 | https://stackoverflow.com/q/2035193 | https://stackoverflow.com/a/2035209 | <p>Prerequisites:</p>
<ul>
<li>You need to be able to run PowerShell as an administrator</li>
<li>You need to set your PowerShell execution policy to a permissive value or be able to bypass it</li>
</ul>
<p>Steps:</p>
<ol>
<li><p>Launch Windows PowerShell as an Administrator, and wait for the <code>PS></code> prompt... | <p>Prerequisites:</p> <ul> <li>You need to be able to run PowerShell as an administrator</li> <li>You need to set your PowerShell execution policy to a permissive value or be able to bypass it</li> </ul> <p>Steps:</p> <ol> <li><p>Launch Windows PowerShell as an Administrator, and wait for the <code>PS></code> prompt... | 64, 526, 531 | powershell, scripting, windows | <h1>How to run a PowerShell script</h1>
<p>How do I run a PowerShell script?</p>
<ul>
<li>I have a script named myscript.ps1</li>
<li>I have all the necessary frameworks installed</li>
<li>I set that <a href="https://stackoverflow.com/questions/10635/why-dont-my-powershell-scripts-run">execution policy</a> thing</li>
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 130 | bash | # How to run a PowerShell script
How do I run a PowerShell script?
- I have a script named myscript.ps1
- I have all the necessary frameworks installed
- I set that [execution policy](https://stackoverflow.com/questions/10635/why-dont-my-powershell-scripts-run) thing
- I have followed the instructions on [this MSDN h... | Prerequisites:
- You need to be able to run PowerShell as an administrator
- You need to set your PowerShell execution policy to a permissive value or be able to bypass it
Steps:
1. Launch Windows PowerShell as an Administrator, and wait for the `PS>` prompt to appear
2. Navigate within PowerShell to the directory w... |
5130847 | Running multiple commands in one line in shell | 549 | 2011-02-27 01:36:10 | <p>Say I have a file <code>/templates/apple</code> and I want to</p>
<ol>
<li>put it in two different places and then</li>
<li>remove the original.</li>
</ol>
<p>So, <code>/templates/apple</code> will be copied to <code>/templates/used</code> AND <code>/templates/inuse</code>
and then after that I’d like to remove th... | 784,259 | 460,121 | 2025-03-01 19:23:36 | 5,130,889 | 1,104 | 2011-02-27 01:44:56 | 412,080 | 2024-06-30 22:42:01 | https://stackoverflow.com/q/5130847 | https://stackoverflow.com/a/5130889 | <p>You are using <code>|</code> (pipe) to direct the output of a command into another command. What you are looking for is <code>&&</code> operator to execute the next command only if the previous one succeeded:</p>
<pre><code>cp /templates/apple /templates/used && cp /templates/apple /templates/inuse &... | <p>You are using <code>|</code> (pipe) to direct the output of a command into another command. What you are looking for is <code>&&</code> operator to execute the next command only if the previous one succeeded:</p> <pre><code>cp /templates/apple /templates/used && cp /templates/apple /templates/inuse &... | 387, 390 | bash, shell | <h1>Running multiple commands in one line in shell</h1>
<p>Say I have a file <code>/templates/apple</code> and I want to</p>
<ol>
<li>put it in two different places and then</li>
<li>remove the original.</li>
</ol>
<p>So, <code>/templates/apple</code> will be copied to <code>/templates/used</code> AND <code>/template... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 131 | bash | # Running multiple commands in one line in shell
Say I have a file `/templates/apple` and I want to
1. put it in two different places and then
2. remove the original.
So, `/templates/apple` will be copied to `/templates/used` AND `/templates/inuse`
and then after that I’d like to remove the original.
Is `cp` the be... | You are using `|` (pipe) to direct the output of a command into another command. What you are looking for is `&&` operator to execute the next command only if the previous one succeeded:
```
cp /templates/apple /templates/used && cp /templates/apple /templates/inuse && rm /templates/apple
```
Or
```
cp /templates/ap... |
3915040 | How to obtain the absolute path of a file via Shell (BASH/ZSH/SH)? | 775 | 2010-10-12 13:12:09 | <p>Question: is there a simple sh/bash/zsh/fish/... command to print the absolute path of whichever file I feed it?</p>
<p>Usage case: I'm in directory <code>/a/b</code> and I'd like to print the full path to file <code>c</code> on the command-line so that I can easily paste it into another program: <code>/a/b/c</code... | 698,349 | 314,345 | 2024-04-15 09:52:30 | 3,915,075 | 1,103 | 2010-10-12 13:16:11 | 176,922 | 2020-08-24 23:52:56 | https://stackoverflow.com/q/3915040 | https://stackoverflow.com/a/3915075 | <p>Use <a href="https://man7.org/linux/man-pages/man1/realpath.1.html" rel="noreferrer"><code>realpath</code></a></p>
<pre><code>$ realpath example.txt
/home/username/example.txt
</code></pre>
| <p>Use <a href="https://man7.org/linux/man-pages/man1/realpath.1.html" rel="noreferrer"><code>realpath</code></a></p> <pre><code>$ realpath example.txt /home/username/example.txt </code></pre> | 387, 390, 6268 | bash, path, shell | <h1>How to obtain the absolute path of a file via Shell (BASH/ZSH/SH)?</h1>
<p>Question: is there a simple sh/bash/zsh/fish/... command to print the absolute path of whichever file I feed it?</p>
<p>Usage case: I'm in directory <code>/a/b</code> and I'd like to print the full path to file <code>c</code> on the command... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 132 | bash | # How to obtain the absolute path of a file via Shell (BASH/ZSH/SH)?
Question: is there a simple sh/bash/zsh/fish/... command to print the absolute path of whichever file I feed it?
Usage case: I'm in directory `/a/b` and I'd like to print the full path to file `c` on the command-line so that I can easily paste it in... | Use [`realpath`](https://man7.org/linux/man-pages/man1/realpath.1.html)
```
$ realpath example.txt
/home/username/example.txt
``` |
981601 | Colorized grep -- viewing the entire file with highlighted matches | 710 | 2009-06-11 14:55:29 | <p>I find <code>grep</code>'s <code>--color=always</code> flag to be tremendously useful. However, grep only prints lines with matches (unless you ask for context lines). Given that each line it prints has a match, the highlighting doesn't add as much capability as it could.</p>
<p>I'd really like to <code>cat</code> ... | 354,153 | 109,549 | 2024-12-29 10:54:43 | 981,831 | 1,096 | 2009-06-11 15:30:58 | 88,894 | 2021-04-25 12:35:22 | https://stackoverflow.com/q/981601 | https://stackoverflow.com/a/981831 | <p>Here are some ways to do it:</p>
<pre><code>grep --color 'pattern\|$' file
grep --color -E 'pattern|$' file
egrep --color 'pattern|$' file
</code></pre>
<p>The <code>|</code> symbol is the OR operator. Either escape it using <code>\</code> or tell grep that the search text has to be interpreted as regular expression... | <p>Here are some ways to do it:</p> <pre><code>grep --color 'pattern\|$' file grep --color -E 'pattern|$' file egrep --color 'pattern|$' file </code></pre> <p>The <code>|</code> symbol is the OR operator. Either escape it using <code>\</code> or tell grep that the search text has to be interpreted as regular expression... | 387, 390, 1271, 6439 | bash, colors, grep, shell | <h1>Colorized grep -- viewing the entire file with highlighted matches</h1>
<p>I find <code>grep</code>'s <code>--color=always</code> flag to be tremendously useful. However, grep only prints lines with matches (unless you ask for context lines). Given that each line it prints has a match, the highlighting doesn't add ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 133 | bash | # Colorized grep -- viewing the entire file with highlighted matches
I find `grep`'s `--color=always` flag to be tremendously useful. However, grep only prints lines with matches (unless you ask for context lines). Given that each line it prints has a match, the highlighting doesn't add as much capability as it could.... | Here are some ways to do it:
```
grep --color 'pattern\|$' file
grep --color -E 'pattern|$' file
egrep --color 'pattern|$' file
```
The `|` symbol is the OR operator. Either escape it using `\` or tell grep that the search text has to be interpreted as regular expressions by adding -E or using the `egrep` command ins... |
692000 | How do I write standard error to a file while using "tee" with a pipe? | 826 | 2009-03-28 01:53:04 | <p>I know how to use <code>tee</code> to write the output (<a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29" rel="noreferrer">standard output</a>) of <code>aaa.sh</code> to <code>bbb.out</code>, while still displaying it in the terminal:</p>
<pre class="lang-none prettyprint-override... | 434,764 | 82,856 | 2025-09-02 10:42:20 | 692,407 | 1,094 | 2009-03-28 07:54:59 | 58,803 | 2022-04-12 22:38:55 | https://stackoverflow.com/q/692000 | https://stackoverflow.com/a/692407 | <p>I'm assuming you want to still see standard error and standard output on the terminal. You could go for <a href="https://stackoverflow.com/questions/692000/how-do-i-write-standard-error-to-a-file-while-using-tee-with-a-pipe/692009#692009">Josh Kelley's answer</a>, but I find keeping a <code>tail</code> around in th... | <p>I'm assuming you want to still see standard error and standard output on the terminal. You could go for <a href="https://stackoverflow.com/questions/692000/how-do-i-write-standard-error-to-a-file-while-using-tee-with-a-pipe/692009#692009">Josh Kelley's answer</a>, but I find keeping a <code>tail</code> around in th... | 34, 58, 387, 22055 | bash, linux, tee, unix | <h1>How do I write standard error to a file while using "tee" with a pipe?</h1>
<p>I know how to use <code>tee</code> to write the output (<a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29" rel="noreferrer">standard output</a>) of <code>aaa.sh</code> to <code>bbb.out</code>, while sti... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 134 | bash | # How do I write standard error to a file while using "tee" with a pipe?
I know how to use `tee` to write the output ([standard output](https://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29)) of `aaa.sh` to `bbb.out`, while still displaying it in the terminal:
```
./aaa.sh | tee bbb.out
```
How... | I'm assuming you want to still see standard error and standard output on the terminal. You could go for [Josh Kelley's answer](https://stackoverflow.com/questions/692000/how-do-i-write-standard-error-to-a-file-while-using-tee-with-a-pipe/692009#692009), but I find keeping a `tail` around in the background which outputs... |
21297853 | How to determine SSL cert expiration date from a PEM encoded certificate? | 602 | 2014-01-23 01:55:19 | <p>If I have the actual file and a Bash shell in Mac or Linux, how can I query the cert file for when it will expire? Not a web site, but actually the certificate file itself, assuming I have the csr, key, pem and chain files.</p>
| 959,584 | 2,117,603 | 2025-04-10 08:19:41 | 21,297,927 | 1,094 | 2014-01-23 02:01:49 | 1,899,640 | 2015-07-31 17:21:40 | https://stackoverflow.com/q/21297853 | https://stackoverflow.com/a/21297927 | <p>With <code>openssl</code>:</p>
<pre><code>openssl x509 -enddate -noout -in file.pem
</code></pre>
<p>The output is on the form:</p>
<pre><code>notAfter=Nov 3 22:23:50 2014 GMT
</code></pre>
<p>Also see <a href="https://stackoverflow.com/a/31718838/1899640">MikeW's answer</a> for how to easily check whether the ... | <p>With <code>openssl</code>:</p> <pre><code>openssl x509 -enddate -noout -in file.pem </code></pre> <p>The output is on the form:</p> <pre><code>notAfter=Nov 3 22:23:50 2014 GMT </code></pre> <p>Also see <a href="https://stackoverflow.com/a/31718838/1899640">MikeW's answer</a> for how to easily check whether the ... | 58, 387, 641, 1999, 5954 | bash, certificate, linux, openssl, ssl | <h1>How to determine SSL cert expiration date from a PEM encoded certificate?</h1>
<p>If I have the actual file and a Bash shell in Mac or Linux, how can I query the cert file for when it will expire? Not a web site, but actually the certificate file itself, assuming I have the csr, key, pem and chain files.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 135 | bash | # How to determine SSL cert expiration date from a PEM encoded certificate?
If I have the actual file and a Bash shell in Mac or Linux, how can I query the cert file for when it will expire? Not a web site, but actually the certificate file itself, assuming I have the csr, key, pem and chain files. | With `openssl`:
```
openssl x509 -enddate -noout -in file.pem
```
The output is on the form:
```
notAfter=Nov 3 22:23:50 2014 GMT
```
Also see [MikeW's answer](https://stackoverflow.com/a/31718838/1899640) for how to easily check whether the certificate has expired or not, or whether it will within a certain time ... |
23929235 | Multi-line string with extra space (preserved indentation) | 744 | 2014-05-29 08:44:38 | <p>I want to write some pre-defined texts to a file with the following:</p>
<pre><code>text="this is line one\n
this is line two\n
this is line three"
echo -e $text > filename
</code></pre>
<p>I'm expecting something like this:</p>
<pre><code>this is line one
this is line two
this is line three
</code></pre>
<p... | 1,000,043 | 1,925,083 | 2025-11-23 21:04:07 | 23,930,212 | 1,078 | 2014-05-29 09:37:12 | 2,794,538 | 2025-11-23 21:03:18 | https://stackoverflow.com/q/23929235 | https://stackoverflow.com/a/23930212 | <p><a href="https://en.wikipedia.org/wiki/Here_document" rel="nofollow noreferrer">Heredoc</a> sounds more convenient for this purpose. It is used to send multiple commands to a command interpreter program, like <em><a href="https://en.wikipedia.org/wiki/Ex_%28text_editor%29" rel="nofollow noreferrer">ex</a></em> or <e... | <p><a href="https://en.wikipedia.org/wiki/Here_document" rel="nofollow noreferrer">Heredoc</a> sounds more convenient for this purpose. It is used to send multiple commands to a command interpreter program, like <em><a href="https://en.wikipedia.org/wiki/Ex_%28text_editor%29" rel="nofollow noreferrer">ex</a></em> or <e... | 139, 387, 390, 13824 | bash, echo, shell, string | <h1>Multi-line string with extra space (preserved indentation)</h1>
<p>I want to write some pre-defined texts to a file with the following:</p>
<pre><code>text="this is line one\n
this is line two\n
this is line three"
echo -e $text > filename
</code></pre>
<p>I'm expecting something like this:</p>
<pre><code>th... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 136 | bash | # Multi-line string with extra space (preserved indentation)
I want to write some pre-defined texts to a file with the following:
```
text="this is line one\n
this is line two\n
this is line three"
echo -e $text > filename
```
I'm expecting something like this:
```
this is line one
this is line two
this is line th... | [Heredoc](https://en.wikipedia.org/wiki/Here_document) sounds more convenient for this purpose. It is used to send multiple commands to a command interpreter program, like *[ex](https://en.wikipedia.org/wiki/Ex_%28text_editor%29)* or *[cat](https://en.wikipedia.org/wiki/Cat_(Unix))*
```
cat << EndOfMessage
This is lin... |
15113413 | How do I concatenate strings and variables in PowerShell? | 1,000 | 2013-02-27 13:34:02 | <p>Suppose I have the following snippet:</p>
<pre class="lang-powershell prettyprint-override"><code>$assoc = New-Object PSObject -Property @{
Id = 42
Name = "Slim Shady"
Owner = "Eminem"
}
Write-Host $assoc.Id + " - " + $assoc.Name + " - " + $assoc.Owner
</code... | 2,549,490 | 1,389,663 | 2024-01-10 14:09:28 | 15,113,467 | 1,074 | 2013-02-27 13:37:03 | 311,712 | 2024-01-10 14:09:28 | https://stackoverflow.com/q/15113413 | https://stackoverflow.com/a/15113467 | <pre><code>Write-Host "$($assoc.Id) - $($assoc.Name) - $($assoc.Owner)"
</code></pre>
<p>See the <a href="https://www.microsoft.com/en-us/download/details.aspx?id=36389" rel="noreferrer">Windows PowerShell Language Specification Version 3.0</a>, p25, sub-expressions expansion.</p>
| <pre><code>Write-Host "$($assoc.Id) - $($assoc.Name) - $($assoc.Owner)" </code></pre> <p>See the <a href="https://www.microsoft.com/en-us/download/details.aspx?id=36389" rel="noreferrer">Windows PowerShell Language Specification Version 3.0</a>, p25, sub-expressions expansion.</p> | 526, 7792 | powershell, string-concatenation | <h1>How do I concatenate strings and variables in PowerShell?</h1>
<p>Suppose I have the following snippet:</p>
<pre class="lang-powershell prettyprint-override"><code>$assoc = New-Object PSObject -Property @{
Id = 42
Name = "Slim Shady"
Owner = "Eminem"
}
Write-Host $assoc.Id + " ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 137 | bash | # How do I concatenate strings and variables in PowerShell?
Suppose I have the following snippet:
```
$assoc = New-Object PSObject -Property @{
Id = 42
Name = "Slim Shady"
Owner = "Eminem"
}
Write-Host $assoc.Id + " - " + $assoc.Name + " - " + $assoc.Owner
```
I'd expect this snippet to show:
> `4... | ```
Write-Host "$($assoc.Id) - $($assoc.Name) - $($assoc.Owner)"
```
See the [Windows PowerShell Language Specification Version 3.0](https://www.microsoft.com/en-us/download/details.aspx?id=36389), p25, sub-expressions expansion. |
36724209 | How to disable bells/beeps in the WSL terminal on Windows 10 | 718 | 2016-04-19 16:26:44 | <p>How do I disable visual and audio bells/beeps in Windows Subsystem for Linux (WSL) on Windows 10?</p>
| 282,036 | 3,943,047 | 2025-06-03 19:48:41 | 36,726,662 | 1,074 | 2016-04-19 18:32:14 | 3,943,047 | 2021-12-29 18:17:38 | https://stackoverflow.com/q/36724209 | https://stackoverflow.com/a/36726662 | <ol>
<li><p>To disable the beep in <strong>bash</strong> you need to uncomment (or add if not already there) the line <code>set bell-style none</code> in your <code>/etc/inputrc</code> file.</p>
<p><em>Note:</em> Since it is a protected file you need to be a privileged user to edit it (i.e. launch your text editor with... | <ol> <li><p>To disable the beep in <strong>bash</strong> you need to uncomment (or add if not already there) the line <code>set bell-style none</code> in your <code>/etc/inputrc</code> file.</p> <p><em>Note:</em> Since it is a protected file you need to be a privileged user to edit it (i.e. launch your text editor with... | 387, 107329, 119526 | bash, windows-10, windows-subsystem-for-linux | <h1>How to disable bells/beeps in the WSL terminal on Windows 10</h1>
<p>How do I disable visual and audio bells/beeps in Windows Subsystem for Linux (WSL) on Windows 10?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 138 | bash | # How to disable bells/beeps in the WSL terminal on Windows 10
How do I disable visual and audio bells/beeps in Windows Subsystem for Linux (WSL) on Windows 10? | 1. To disable the beep in **bash** you need to uncomment (or add if not already there) the line `set bell-style none` in your `/etc/inputrc` file.
*Note:* Since it is a protected file you need to be a privileged user to edit it (i.e. launch your text editor with something like `sudo <editor> /etc/inputrc`).
2. To d... |
637827 | Redirect stderr and stdout in Bash | 961 | 2009-03-12 09:14:05 | <p>I want to redirect both <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_(stdout)" rel="noreferrer">standard output</a> and <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_error_(stderr)" rel="noreferrer">standard error</a> of a process to a single file. How do I do that in Ba... | 1,180,724 | 63,051 | 2025-10-20 21:44:30 | 637,839 | 1,065 | 2009-03-12 09:17:25 | 66,692 | 2025-10-20 21:40:48 | https://stackoverflow.com/q/637827 | https://stackoverflow.com/a/637839 | <p>Take a look <a href="https://tldp.org/LDP/abs/html/io-redirection.html" rel="noreferrer">here</a>. It should be:</p>
<pre><code>yourcommand &> filename
</code></pre>
<p>It redirects both standard output and standard error to file <em>filename</em>.</p>
| <p>Take a look <a href="https://tldp.org/LDP/abs/html/io-redirection.html" rel="noreferrer">here</a>. It should be:</p> <pre><code>yourcommand &> filename </code></pre> <p>It redirects both standard output and standard error to file <em>filename</em>.</p> | 387, 390, 4867, 19156, 26698 | bash, io-redirection, shell, stderr, stdout | <h1>Redirect stderr and stdout in Bash</h1>
<p>I want to redirect both <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_output_(stdout)" rel="noreferrer">standard output</a> and <a href="https://en.wikipedia.org/wiki/Standard_streams#Standard_error_(stderr)" rel="noreferrer">standard error</a> of a proc... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 139 | bash | # Redirect stderr and stdout in Bash
I want to redirect both [standard output](https://en.wikipedia.org/wiki/Standard_streams#Standard_output_(stdout)) and [standard error](https://en.wikipedia.org/wiki/Standard_streams#Standard_error_(stderr)) of a process to a single file. How do I do that in Bash? | Take a look [here](https://tldp.org/LDP/abs/html/io-redirection.html). It should be:
```
yourcommand &> filename
```
It redirects both standard output and standard error to file *filename*. |
13799789 | Expansion of variables inside single quotes in a command in Bash | 696 | 2012-12-10 11:10:13 | <p>I want to run a command from a <em>bash script</em> which has single quotes and some other commands inside the single quotes and a variable.</p>
<p>e.g. <code>repo forall -c '....$variable'</code></p>
<p>In this format, <code>$</code> is escaped and the variable is not expanded.</p>
<p>I tried the following varia... | 722,106 | 1,879,748 | 2025-06-02 02:59:01 | 13,802,438 | 1,062 | 2012-12-10 14:00:30 | 1,073,695 | 2019-06-19 14:19:27 | https://stackoverflow.com/q/13799789 | https://stackoverflow.com/a/13802438 | <p>Inside single quotes everything is preserved literally, without exception.</p>
<p>That means you have to close the quotes, insert something, and then re-enter again.</p>
<pre><code>'before'"$variable"'after'
'before'"'"'after'
'before'\''after'
</code></pre>
<p>Word concatenation is simply done by juxtaposition. ... | <p>Inside single quotes everything is preserved literally, without exception.</p> <p>That means you have to close the quotes, insert something, and then re-enter again.</p> <pre><code>'before'"$variable"'after' 'before'"'"'after' 'before'\''after' </code></pre> <p>Word concatenation is simply done by juxtaposition. ... | 276, 387, 390, 430 | bash, quotes, shell, variables | <h1>Expansion of variables inside single quotes in a command in Bash</h1>
<p>I want to run a command from a <em>bash script</em> which has single quotes and some other commands inside the single quotes and a variable.</p>
<p>e.g. <code>repo forall -c '....$variable'</code></p>
<p>In this format, <code>$</code> is esc... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 140 | bash | # Expansion of variables inside single quotes in a command in Bash
I want to run a command from a *bash script* which has single quotes and some other commands inside the single quotes and a variable.
e.g. `repo forall -c '....$variable'`
In this format, `$` is escaped and the variable is not expanded.
I tried the ... | Inside single quotes everything is preserved literally, without exception.
That means you have to close the quotes, insert something, and then re-enter again.
```
'before'"$variable"'after'
'before'"'"'after'
'before'\''after'
```
Word concatenation is simply done by juxtaposition. As you can verify, each of the abo... |
3258243 | Check if pull needed in Git | 769 | 2010-07-15 17:32:27 | <p>How do I check whether the remote repository has changed and I need to pull?</p>
<p>Now I use this simple script:</p>
<pre><code>git pull --dry-run | grep -q -v 'Already up-to-date.' && changed=1
</code></pre>
<p>But it is rather heavy.</p>
<p>Is there a better way? The ideal solution would check all the... | 522,058 | 234,780 | 2025-01-01 00:48:27 | 3,278,427 | 1,045 | 2010-07-19 04:18:54 | 381,619 | 2022-03-14 17:04:09 | https://stackoverflow.com/q/3258243 | https://stackoverflow.com/a/3278427 | <p>First use <a href="https://git-scm.com/docs/git-remote" rel="noreferrer"><code>git remote update</code></a>, to bring your remote refs up to date. Then you can do one of several things, such as:</p>
<ol>
<li><p><code>git status -uno</code> will tell you whether the branch you are tracking is ahead, behind or has div... | <p>First use <a href="https://git-scm.com/docs/git-remote" rel="noreferrer"><code>git remote update</code></a>, to bring your remote refs up to date. Then you can do one of several things, such as:</p> <ol> <li><p><code>git status -uno</code> will tell you whether the branch you are tracking is ahead, behind or has div... | 119, 387, 390 | bash, git, shell | <h1>Check if pull needed in Git</h1>
<p>How do I check whether the remote repository has changed and I need to pull?</p>
<p>Now I use this simple script:</p>
<pre><code>git pull --dry-run | grep -q -v 'Already up-to-date.' && changed=1
</code></pre>
<p>But it is rather heavy.</p>
<p>Is there a better way? T... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 141 | bash | # Check if pull needed in Git
How do I check whether the remote repository has changed and I need to pull?
Now I use this simple script:
```
git pull --dry-run | grep -q -v 'Already up-to-date.' && changed=1
```
But it is rather heavy.
Is there a better way? The ideal solution would check all the remote branches, ... | First use [`git remote update`](https://git-scm.com/docs/git-remote), to bring your remote refs up to date. Then you can do one of several things, such as:
1. `git status -uno` will tell you whether the branch you are tracking is ahead, behind or has diverged. If it says nothing, the local and remote are the same.
2. ... |
8789729 | How to zero pad a sequence of integers in bash so that all have the same width? | 647 | 2012-01-09 14:12:18 | <p>I need to loop some values,</p>
<pre><code>for i in $(seq $first $last)
do
does something here
done
</code></pre>
<p>For <code>$first</code> and <code>$last</code>, I need it to be of fixed length 5. So if the input is <code>1</code>, I need to add zeros in front such that it becomes <code>00001</code>. It loops... | 440,335 | 1,138,842 | 2024-10-26 13:39:32 | 8,789,815 | 1,044 | 2012-01-09 14:17:43 | 3,171 | 2012-01-09 14:26:12 | https://stackoverflow.com/q/8789729 | https://stackoverflow.com/a/8789815 | <p>In your specific case though it's probably easiest to use the <code>-f</code> flag to <code>seq</code> to get it to format the numbers as it outputs the list. For example:</p>
<pre><code>for i in $(seq -f "%05g" 10 15)
do
echo $i
done
</code></pre>
<p>will produce the following output:</p>
<pre><code>00010
000... | <p>In your specific case though it's probably easiest to use the <code>-f</code> flag to <code>seq</code> to get it to format the numbers as it outputs the list. For example:</p> <pre><code>for i in $(seq -f "%05g" 10 15) do echo $i done </code></pre> <p>will produce the following output:</p> <pre><code>00010 000... | 387, 3496, 9282 | bash, numbers, padding | <h1>How to zero pad a sequence of integers in bash so that all have the same width?</h1>
<p>I need to loop some values,</p>
<pre><code>for i in $(seq $first $last)
do
does something here
done
</code></pre>
<p>For <code>$first</code> and <code>$last</code>, I need it to be of fixed length 5. So if the input is <code... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 142 | bash | # How to zero pad a sequence of integers in bash so that all have the same width?
I need to loop some values,
```
for i in $(seq $first $last)
do
does something here
done
```
For `$first` and `$last`, I need it to be of fixed length 5. So if the input is `1`, I need to add zeros in front such that it becomes `00... | In your specific case though it's probably easiest to use the `-f` flag to `seq` to get it to format the numbers as it outputs the list. For example:
```
for i in $(seq -f "%05g" 10 15)
do
echo $i
done
```
will produce the following output:
```
00010
00011
00012
00013
00014
00015
```
More generally, `bash` has `p... |
4111475 | How to do a logical OR operation for integer comparison in shell scripting? | 593 | 2010-11-06 01:48:33 | <p>I am trying to do a simple condition check, but it doesn't seem to work.</p>
<p>If <code>$#</code> is equal to <code>0</code> or is greater than <code>1</code> then say hello.</p>
<p>I have tried the following syntax with no success:</p>
<pre><code>if [ "$#" == 0 -o "$#" > 1 ] ; then
echo "hello"
fi
if [ "$#... | 1,038,318 | 170,365 | 2021-02-23 13:04:53 | 4,111,510 | 1,033 | 2010-11-06 02:03:12 | 148,217 | 2018-04-26 10:40:20 | https://stackoverflow.com/q/4111475 | https://stackoverflow.com/a/4111510 | <p>This should work:</p>
<pre><code>#!/bin/bash
if [ "$#" -eq 0 ] || [ "$#" -gt 1 ] ; then
echo "hello"
fi
</code></pre>
<p>I'm not sure if this is different in other shells but if you wish to use <, >, you need to put them inside double parenthesis like so: </p>
<pre><code>if (("$#" > 1))
...
</code></p... | <p>This should work:</p> <pre><code>#!/bin/bash if [ "$#" -eq 0 ] || [ "$#" -gt 1 ] ; then echo "hello" fi </code></pre> <p>I'm not sure if this is different in other shells but if you wish to use <, >, you need to put them inside double parenthesis like so: </p> <pre><code>if (("$#" > 1)) ... </code></p... | 34, 387, 2773, 10327 | bash, if-statement, sh, unix | <h1>How to do a logical OR operation for integer comparison in shell scripting?</h1>
<p>I am trying to do a simple condition check, but it doesn't seem to work.</p>
<p>If <code>$#</code> is equal to <code>0</code> or is greater than <code>1</code> then say hello.</p>
<p>I have tried the following syntax with no succe... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 143 | bash | # How to do a logical OR operation for integer comparison in shell scripting?
I am trying to do a simple condition check, but it doesn't seem to work.
If `$#` is equal to `0` or is greater than `1` then say hello.
I have tried the following syntax with no success:
```
if [ "$#" == 0 -o "$#" > 1 ] ; then
echo "hell... | This should work:
```
#!/bin/bash
if [ "$#" -eq 0 ] || [ "$#" -gt 1 ] ; then
echo "hello"
fi
```
I'm not sure if this is different in other shells but if you wish to use <, >, you need to put them inside double parenthesis like so:
```
if (("$#" > 1))
...
``` |
3349105 | How can I set the current working directory to the directory of the script in Bash? | 851 | 2010-07-28 00:43:29 | <p>I'm writing a Bash script. I need the current working directory to always be the directory that the script is located in.</p>
<p>The default behavior is that the current working directory in the script is that of the shell from which I run it, but I do not want this behavior.</p>
| 688,407 | 229,792 | 2025-03-11 07:14:36 | 3,355,423 | 1,029 | 2010-07-28 17:04:38 | 182,675 | 2025-03-11 07:14:36 | https://stackoverflow.com/q/3349105 | https://stackoverflow.com/a/3355423 | <h2>TL;DR</h2>
<pre class="lang-bash prettyprint-override"><code>#!/usr/bin/env bash
cd "$(dirname "$0")"
</code></pre>
<h2>The explanation</h2>
<p>How does this work and how does it deal with edge and corner cases?</p>
<ul>
<li>You type a script invocation command into your interactive shell, which... | <h2>TL;DR</h2> <pre class="lang-bash prettyprint-override"><code>#!/usr/bin/env bash cd "$(dirname "$0")" </code></pre> <h2>The explanation</h2> <p>How does this work and how does it deal with edge and corner cases?</p> <ul> <li>You type a script invocation command into your interactive shell, which... | 387, 531, 6268 | bash, path, scripting | <h1>How can I set the current working directory to the directory of the script in Bash?</h1>
<p>I'm writing a Bash script. I need the current working directory to always be the directory that the script is located in.</p>
<p>The default behavior is that the current working directory in the script is that of the shell f... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 144 | bash | # How can I set the current working directory to the directory of the script in Bash?
I'm writing a Bash script. I need the current working directory to always be the directory that the script is located in.
The default behavior is that the current working directory in the script is that of the shell from which I run... | ## TL;DR
```
#!/usr/bin/env bash
cd "$(dirname "$0")"
```
## The explanation
How does this work and how does it deal with edge and corner cases?
- You type a script invocation command into your interactive shell, which may or may not be bash.
- That interactive shell tells the kernel to execute the script from the ... |
3327013 | How to determine the current interactive shell that I'm in (command-line) | 864 | 2010-07-24 21:35:28 | <p>How can I determine the current shell I am working on? </p>
<p>Would the output of the <code>ps</code> command alone be sufficient?</p>
<p>How can this be done in different flavors of Unix?</p>
| 721,729 | 268,543 | 2025-03-13 15:38:33 | 3,327,022 | 1,024 | 2010-07-24 21:37:34 | 119,280 | 2025-03-13 15:38:33 | https://stackoverflow.com/q/3327013 | https://stackoverflow.com/a/3327022 | <p>There are three approaches to finding the <strong>name</strong> of the current shell's executable:</p>
<p>Please note that all three approaches can be fooled if the executable of the shell is <code>/bin/sh</code>, but it's really a renamed <code>bash</code>, for example (which frequently happens).</p>
<p><em>Thus yo... | <p>There are three approaches to finding the <strong>name</strong> of the current shell's executable:</p> <p>Please note that all three approaches can be fooled if the executable of the shell is <code>/bin/sh</code>, but it's really a renamed <code>bash</code>, for example (which frequently happens).</p> <p><em>Thus yo... | 34, 387, 390, 2829, 8599 | bash, csh, shell, tcsh, unix | <h1>How to determine the current interactive shell that I'm in (command-line)</h1>
<p>How can I determine the current shell I am working on? </p>
<p>Would the output of the <code>ps</code> command alone be sufficient?</p>
<p>How can this be done in different flavors of Unix?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 145 | bash | # How to determine the current interactive shell that I'm in (command-line)
How can I determine the current shell I am working on?
Would the output of the `ps` command alone be sufficient?
How can this be done in different flavors of Unix? | There are three approaches to finding the **name** of the current shell's executable:
Please note that all three approaches can be fooled if the executable of the shell is `/bin/sh`, but it's really a renamed `bash`, for example (which frequently happens).
*Thus your second question of whether `ps` output will do is ... |
821396 | Aborting a shell script if any command returns a non-zero value | 628 | 2009-05-04 18:55:50 | <p>I have a Bash shell script that invokes a number of commands.</p>
<p>I would like to have the shell script automatically exit with a return value of 1 if any of the commands return a non-zero value.</p>
<p>Is this possible without explicitly checking the result of each command?</p>
<p>For example,</p>
<pre><code>dos... | 276,104 | 93,430 | 2024-10-28 09:37:39 | 821,419 | 1,010 | 2009-05-04 19:00:16 | 7,446 | 2022-09-14 21:23:55 | https://stackoverflow.com/q/821396 | https://stackoverflow.com/a/821419 | <p>Add this to the beginning of the script:</p>
<pre><code>set -e
</code></pre>
<p>This will cause the shell to exit immediately if a simple command exits with a nonzero exit value. A simple command is any command not part of an <code>if</code>, <code>while</code>, or <code>until</code> test, or part of an <code>&... | <p>Add this to the beginning of the script:</p> <pre><code>set -e </code></pre> <p>This will cause the shell to exit immediately if a simple command exits with a nonzero exit value. A simple command is any command not part of an <code>if</code>, <code>while</code>, or <code>until</code> test, or part of an <code>&... | 34, 58, 387, 390 | bash, linux, shell, unix | <h1>Aborting a shell script if any command returns a non-zero value</h1>
<p>I have a Bash shell script that invokes a number of commands.</p>
<p>I would like to have the shell script automatically exit with a return value of 1 if any of the commands return a non-zero value.</p>
<p>Is this possible without explicitly ch... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 146 | bash | # Aborting a shell script if any command returns a non-zero value
I have a Bash shell script that invokes a number of commands.
I would like to have the shell script automatically exit with a return value of 1 if any of the commands return a non-zero value.
Is this possible without explicitly checking the result of ... | Add this to the beginning of the script:
```
set -e
```
This will cause the shell to exit immediately if a simple command exits with a nonzero exit value. A simple command is any command not part of an `if`, `while`, or `until` test, or part of an `&&` or `||` list.
See the [bash manual](https://www.gnu.org/software... |
9057387 | Process all arguments except the first one (in a bash script) | 685 | 2012-01-29 22:31:22 | <p>I have a simple script where the first argument is reserved for the filename, and all other optional arguments should be passed to other parts of the script.</p>
<p>Using Google I found <a href="http://wiki.bash-hackers.org/scripting/posparams#mass_usage" rel="noreferrer">this wiki</a>, but it provided a literal exa... | 317,321 | 992,005 | 2024-04-23 15:29:11 | 9,057,392 | 991 | 2012-01-29 22:32:55 | 129,570 | 2016-04-01 02:29:12 | https://stackoverflow.com/q/9057387 | https://stackoverflow.com/a/9057392 | <p>Use this:</p>
<pre><code>echo "${@:2}"
</code></pre>
<hr>
<p>The following syntax:</p>
<pre><code>echo "${*:2}"
</code></pre>
<p>would work as well, but is not recommended, because as <a href="https://stackoverflow.com/questions/9057387/process-all-arguments-except-the-first-one#comment11369452_9057392">@Gordon... | <p>Use this:</p> <pre><code>echo "${@:2}" </code></pre> <hr> <p>The following syntax:</p> <pre><code>echo "${*:2}" </code></pre> <p>would work as well, but is not recommended, because as <a href="https://stackoverflow.com/questions/9057387/process-all-arguments-except-the-first-one#comment11369452_9057392">@Gordon... | 387, 390 | bash, shell | <h1>Process all arguments except the first one (in a bash script)</h1>
<p>I have a simple script where the first argument is reserved for the filename, and all other optional arguments should be passed to other parts of the script.</p>
<p>Using Google I found <a href="http://wiki.bash-hackers.org/scripting/posparams#ma... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 147 | bash | # Process all arguments except the first one (in a bash script)
I have a simple script where the first argument is reserved for the filename, and all other optional arguments should be passed to other parts of the script.
Using Google I found [this wiki](http://wiki.bash-hackers.org/scripting/posparams#mass_usage), b... | Use this:
```
echo "${@:2}"
```
---
The following syntax:
```
echo "${*:2}"
```
would work as well, but is not recommended, because as [@Gordon](https://stackoverflow.com/questions/9057387/process-all-arguments-except-the-first-one#comment11369452_9057392) already explained, that using `*`, it runs all of the argu... |
83329 | How can I extract a predetermined range of lines from a text file on Unix? | 694 | 2008-09-17 13:40:59 | <p>I have a <code>~23000</code> line SQL dump containing several databases worth of data. I need to extract a certain section of this file (i.e. the data for a single database) and place it in a new file. I know both the start and end line numbers of the data that I want.</p>
<p>Does anyone know a Unix command (or seri... | 692,777 | 15,676 | 2024-08-02 22:39:30 | 83,347 | 990 | 2008-09-17 13:42:34 | 15,732 | 2018-06-13 18:09:58 | https://stackoverflow.com/q/83329 | https://stackoverflow.com/a/83347 | <pre><code>sed -n '16224,16482p;16483q' filename > newfile
</code></pre>
<p>From the <a href="https://www.gnu.org/software/sed/manual/sed.html#Common-Commands" rel="noreferrer">sed manual</a>:</p>
<blockquote>
<p><strong>p</strong> -
Print out the pattern space (to the standard output). This command is us... | <pre><code>sed -n '16224,16482p;16483q' filename > newfile </code></pre> <p>From the <a href="https://www.gnu.org/software/sed/manual/sed.html#Common-Commands" rel="noreferrer">sed manual</a>:</p> <blockquote> <p><strong>p</strong> - Print out the pattern space (to the standard output). This command is us... | 387, 1718 | bash, text-processing | <h1>How can I extract a predetermined range of lines from a text file on Unix?</h1>
<p>I have a <code>~23000</code> line SQL dump containing several databases worth of data. I need to extract a certain section of this file (i.e. the data for a single database) and place it in a new file. I know both the start and end l... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 148 | bash | # How can I extract a predetermined range of lines from a text file on Unix?
I have a `~23000` line SQL dump containing several databases worth of data. I need to extract a certain section of this file (i.e. the data for a single database) and place it in a new file. I know both the start and end line numbers of the d... | ```
sed -n '16224,16482p;16483q' filename > newfile
```
From the [sed manual](https://www.gnu.org/software/sed/manual/sed.html#Common-Commands):
> **p** -
> Print out the pattern space (to the standard output). This command is usually only used in conjunction with the -n command-line option.
>
> **n** -
> If auto-pri... |
5130968 | How can I copy the output of a command directly into my clipboard? | 927 | 2011-02-27 02:10:46 | <p>How can I pipe the output of a command into my clipboard and paste it back when using a terminal? For instance:</p>
<pre><code>cat file | clipboard
</code></pre>
| 886,690 | 184,046 | 2025-05-27 14:38:10 | 5,130,969 | 989 | 2011-02-27 02:11:09 | 184,046 | 2023-05-17 09:17:49 | https://stackoverflow.com/q/5130968 | https://stackoverflow.com/a/5130969 | <p>One way of doing it follows:</p>
<ol>
<li><p>Install <code>xclip</code>, such as:</p>
<p><code>sudo apt-get install xclip</code></p>
</li>
<li><p>Pipe the output into <code>xclip</code> to be copied into the clipboard:</p>
<p><code>cat file | xclip</code></p>
</li>
<li><p>Paste the text you just copied into a <code>... | <p>One way of doing it follows:</p> <ol> <li><p>Install <code>xclip</code>, such as:</p> <p><code>sudo apt-get install xclip</code></p> </li> <li><p>Pipe the output into <code>xclip</code> to be copied into the clipboard:</p> <p><code>cat file | xclip</code></p> </li> <li><p>Paste the text you just copied into a <code>... | 34, 58, 390, 391, 524 | clipboard, linux, shell, terminal, unix | <h1>How can I copy the output of a command directly into my clipboard?</h1>
<p>How can I pipe the output of a command into my clipboard and paste it back when using a terminal? For instance:</p>
<pre><code>cat file | clipboard
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 149 | bash | # How can I copy the output of a command directly into my clipboard?
How can I pipe the output of a command into my clipboard and paste it back when using a terminal? For instance:
```
cat file | clipboard
``` | One way of doing it follows:
1. Install `xclip`, such as:
`sudo apt-get install xclip`
2. Pipe the output into `xclip` to be copied into the clipboard:
`cat file | xclip`
3. Paste the text you just copied into a `X` application:
`xclip -o`
To paste somewhere else other than an `X` application, such as a t... |
22009364 | Is there a TRY CATCH command in Bash | 671 | 2014-02-25 09:09:14 | <p>I'm writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way.</p>
| 731,713 | 107,567 | 2023-11-21 05:03:10 | 22,010,339 | 989 | 2014-02-25 09:50:02 | 3,150,853 | 2020-02-19 05:20:51 | https://stackoverflow.com/q/22009364 | https://stackoverflow.com/a/22010339 | <blockquote>
<p>Is there a TRY CATCH command in Bash?</p>
</blockquote>
<p>No. </p>
<p>Bash doesn't have as many luxuries as one can find in many programming languages.</p>
<p>There is no <code>try/catch</code> in bash; however, one can achieve similar behavior using <code>&&</code> or <code>||</code>.</p... | <blockquote> <p>Is there a TRY CATCH command in Bash?</p> </blockquote> <p>No. </p> <p>Bash doesn't have as many luxuries as one can find in many programming languages.</p> <p>There is no <code>try/catch</code> in bash; however, one can achieve similar behavior using <code>&&</code> or <code>||</code>.</p... | 379, 387, 390 | bash, error-handling, shell | <h1>Is there a TRY CATCH command in Bash</h1>
<p>I'm writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 150 | bash | # Is there a TRY CATCH command in Bash
I'm writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way. | > Is there a TRY CATCH command in Bash?
No.
Bash doesn't have as many luxuries as one can find in many programming languages.
There is no `try/catch` in bash; however, one can achieve similar behavior using `&&` or `||`.
Using `||`:
if `command1` fails then `command2` runs as follows
```
command1 || command2
```
... |
5064563 | How to add line break to 'git commit -m' from the command line? | 1,119 | 2011-02-21 10:02:42 | <p>I am using Git from the command line and am trying to add a line break to the commit message (using <code>git commit -m ""</code>) without going into Vim.</p>
<p>Is this possible?</p>
| 505,211 | 347,180 | 2024-08-16 08:44:42 | 5,064,653 | 985 | 2011-02-21 10:12:01 | 613,064 | 2019-08-22 11:35:15 | https://stackoverflow.com/q/5064563 | https://stackoverflow.com/a/5064653 | <p>Certainly, how it's done depends on your shell. In Bash, you can use single quotes around the message and can just leave the quote open, which will make Bash prompt for another line, until you close the quote. Like this:</p>
<pre><code>git commit -m 'Message
goes
here'
</code></pre>
<p>Alternatively, you can use ... | <p>Certainly, how it's done depends on your shell. In Bash, you can use single quotes around the message and can just leave the quote open, which will make Bash prompt for another line, until you close the quote. Like this:</p> <pre><code>git commit -m 'Message goes here' </code></pre> <p>Alternatively, you can use ... | 119, 387, 390 | bash, git, shell | <h1>How to add line break to 'git commit -m' from the command line?</h1>
<p>I am using Git from the command line and am trying to add a line break to the commit message (using <code>git commit -m ""</code>) without going into Vim.</p>
<p>Is this possible?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 151 | bash | # How to add line break to 'git commit -m' from the command line?
I am using Git from the command line and am trying to add a line break to the commit message (using `git commit -m ""`) without going into Vim.
Is this possible? | Certainly, how it's done depends on your shell. In Bash, you can use single quotes around the message and can just leave the quote open, which will make Bash prompt for another line, until you close the quote. Like this:
```
git commit -m 'Message
goes
here'
```
Alternatively, you can use a "here document" (also kno... |
3235850 | How to enter a multi-line command | 711 | 2010-07-13 09:36:16 | <p>Is it possible to split a PowerShell command line over multiple lines?</p>
<p>In Visual Basic I can use the underscore (<code>_</code>) to continue the command in the next line.</p>
| 718,654 | 83,004 | 2025-02-13 21:25:50 | 3,235,993 | 985 | 2010-07-13 09:52:44 | 73,070 | 2018-12-13 13:34:50 | https://stackoverflow.com/q/3235850 | https://stackoverflow.com/a/3235993 | <p>You can use a space followed by the grave accent (backtick):</p>
<pre><code>Get-ChildItem -Recurse `
-Filter *.jpg `
| Select LastWriteTime
</code></pre>
<p>However, this is only ever necessary in such cases as shown above. Usually you get automatic line continuation when a command cannot syntactically be comp... | <p>You can use a space followed by the grave accent (backtick):</p> <pre><code>Get-ChildItem -Recurse ` -Filter *.jpg ` | Select LastWriteTime </code></pre> <p>However, this is only ever necessary in such cases as shown above. Usually you get automatic line continuation when a command cannot syntactically be comp... | 526, 10941 | multiline, powershell | <h1>How to enter a multi-line command</h1>
<p>Is it possible to split a PowerShell command line over multiple lines?</p>
<p>In Visual Basic I can use the underscore (<code>_</code>) to continue the command in the next line.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 152 | bash | # How to enter a multi-line command
Is it possible to split a PowerShell command line over multiple lines?
In Visual Basic I can use the underscore (`_`) to continue the command in the next line. | You can use a space followed by the grave accent (backtick):
```
Get-ChildItem -Recurse `
-Filter *.jpg `
| Select LastWriteTime
```
However, this is only ever necessary in such cases as shown above. Usually you get automatic line continuation when a command cannot syntactically be complete at that point. This in... |
5171901 | Find and replace in file and overwrite file doesn't work, it empties the file | 638 | 2011-03-02 18:44:28 | <p>I would like to run a find and replace on an HTML file through the command line.</p>
<p>My command looks something like this:</p>
<pre><code>sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html > index.html
</code></pre>
<p>When I run this and look at the file afterward, it is empty. It deleted the con... | 758,956 | 540,738 | 2019-04-04 19:18:53 | 5,171,935 | 985 | 2011-03-02 18:48:27 | 227,665 | 2012-07-23 07:02:27 | https://stackoverflow.com/q/5171901 | https://stackoverflow.com/a/5171935 | <p>When the <strong>shell</strong> sees <code>> index.html</code> in the command line it opens the file <code>index.html</code> for <strong>writing</strong>, wiping off all its previous contents.</p>
<p>To fix this you need to pass the <code>-i</code> option to <code>sed</code> to make the changes inline and creat... | <p>When the <strong>shell</strong> sees <code>> index.html</code> in the command line it opens the file <code>index.html</code> for <strong>writing</strong>, wiping off all its previous contents.</p> <p>To fix this you need to pass the <code>-i</code> option to <code>sed</code> to make the changes inline and creat... | 34, 390, 5282, 26698 | io-redirection, sed, shell, unix | <h1>Find and replace in file and overwrite file doesn't work, it empties the file</h1>
<p>I would like to run a find and replace on an HTML file through the command line.</p>
<p>My command looks something like this:</p>
<pre><code>sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html > index.html
</code></p... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 153 | bash | # Find and replace in file and overwrite file doesn't work, it empties the file
I would like to run a find and replace on an HTML file through the command line.
My command looks something like this:
```
sed -e s/STRING_TO_REPLACE/STRING_TO_REPLACE_IT/g index.html > index.html
```
When I run this and look at the fil... | When the **shell** sees `> index.html` in the command line it opens the file `index.html` for **writing**, wiping off all its previous contents.
To fix this you need to pass the `-i` option to `sed` to make the changes inline and create a backup of the original file before it does the changes in-place:
```
sed -i.bak... |
16661982 | Check folder size in Bash | 516 | 2013-05-21 04:08:36 | <p>I'm trying to write a script that will calculate a directory size and if the size is less than 10GB, and greater then 2GB do some action. Where do I need to mention my folder name?</p>
<pre><code># 10GB
SIZE="1074747474"
# check the current size
CHECK="`du /data/sflow_log/`"
if [ "$CHECK" -gt "$SIZE" ]; then
ec... | 534,356 | 2,403,913 | 2023-02-19 17:40:02 | 16,662,027 | 981 | 2013-05-21 04:12:55 | 1,246,262 | 2021-06-17 06:53:14 | https://stackoverflow.com/q/16661982 | https://stackoverflow.com/a/16662027 | <p>You can do:</p>
<pre><code>du -hs your_directory
</code></pre>
<p>which will give you a brief output of the size of your target directory. Using a wildcard like <code>*</code> can select multiple directories.</p>
<p>If you want a full listing of sizes for all files and sub-directories inside your target, you can do:... | <p>You can do:</p> <pre><code>du -hs your_directory </code></pre> <p>which will give you a brief output of the size of your target directory. Using a wildcard like <code>*</code> can select multiple directories.</p> <p>If you want a full listing of sizes for all files and sub-directories inside your target, you can do:... | 218, 387, 390 | bash, directory, shell | <h1>Check folder size in Bash</h1>
<p>I'm trying to write a script that will calculate a directory size and if the size is less than 10GB, and greater then 2GB do some action. Where do I need to mention my folder name?</p>
<pre><code># 10GB
SIZE="1074747474"
# check the current size
CHECK="`du /data/sflow_log/`"
if ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 154 | bash | # Check folder size in Bash
I'm trying to write a script that will calculate a directory size and if the size is less than 10GB, and greater then 2GB do some action. Where do I need to mention my folder name?
```
# 10GB
SIZE="1074747474"
# check the current size
CHECK="`du /data/sflow_log/`"
if [ "$CHECK" -gt "$SIZE... | You can do:
```
du -hs your_directory
```
which will give you a brief output of the size of your target directory. Using a wildcard like `*` can select multiple directories.
If you want a full listing of sizes for all files and sub-directories inside your target, you can do:
```
du -h your_directory
```
**Tips:**
... |
221921 | Use grep --exclude/--include syntax to not grep through certain files | 951 | 2008-10-21 13:41:01 | <p>I'm looking for the string <code>foo=</code> in text files in a directory tree. It's on a common Linux machine, I have bash shell:</p>
<pre><code>grep -ircl "foo=" *
</code></pre>
<p>In the directories are also many binary files which match <code>"foo="</code>. As these results are not relevant a... | 913,010 | 19,746 | 2023-07-28 11:13:22 | 221,929 | 979 | 2008-10-21 13:44:01 | 9,530 | 2021-03-04 19:27:56 | https://stackoverflow.com/q/221921 | https://stackoverflow.com/a/221929 | <p>Use the shell <a href="https://man7.org/linux/man-pages/man7/glob.7.html" rel="noreferrer">globbing syntax</a>:</p>
<pre><code>grep pattern -r --include=\*.cpp --include=\*.h rootdir
</code></pre>
<p>The syntax for <code>--exclude</code> is identical.</p>
<p>Note that the star is escaped with a backslash to prevent ... | <p>Use the shell <a href="https://man7.org/linux/man-pages/man7/glob.7.html" rel="noreferrer">globbing syntax</a>:</p> <pre><code>grep pattern -r --include=\*.cpp --include=\*.h rootdir </code></pre> <p>The syntax for <code>--exclude</code> is identical.</p> <p>Note that the star is escaped with a backslash to prevent ... | 34, 390, 816, 1231, 1271 | command-line, grep, search, shell, unix | <h1>Use grep --exclude/--include syntax to not grep through certain files</h1>
<p>I'm looking for the string <code>foo=</code> in text files in a directory tree. It's on a common Linux machine, I have bash shell:</p>
<pre><code>grep -ircl "foo=" *
</code></pre>
<p>In the directories are also many binary files... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 155 | bash | # Use grep --exclude/--include syntax to not grep through certain files
I'm looking for the string `foo=` in text files in a directory tree. It's on a common Linux machine, I have bash shell:
```
grep -ircl "foo=" *
```
In the directories are also many binary files which match `"foo="`. As these results are not rele... | Use the shell [globbing syntax](https://man7.org/linux/man-pages/man7/glob.7.html):
```
grep pattern -r --include=\*.cpp --include=\*.h rootdir
```
The syntax for `--exclude` is identical.
Note that the star is escaped with a backslash to prevent it from being expanded by the shell (quoting it, such as `--include="*... |
6121091 | How to extract directory path from file path? | 619 | 2011-05-25 07:41:44 | <p>In Bash, if <code>VAR="/home/me/mydir/file.c"</code>, how do I get <code>"/home/me/mydir"</code>?</p>
| 672,453 | 579,689 | 2024-03-19 14:33:33 | 6,121,114 | 974 | 2011-05-25 07:44:16 | 14,860 | 2021-08-28 23:57:15 | https://stackoverflow.com/q/6121091 | https://stackoverflow.com/a/6121114 | <p><code>dirname</code> and <code>basename</code> are the tools you're looking for for extracting path components:</p>
<pre><code>$ VAR='/home/pax/file.c'
$ DIR="$(dirname "${VAR}")" ; FILE="$(basename "${VAR}")"
$ echo "[${DIR}] [${FILE}]"
[/home/pax] [file.c]
</code><... | <p><code>dirname</code> and <code>basename</code> are the tools you're looking for for extracting path components:</p> <pre><code>$ VAR='/home/pax/file.c' $ DIR="$(dirname "${VAR}")" ; FILE="$(basename "${VAR}")" $ echo "[${DIR}] [${FILE}]" [/home/pax] [file.c] </code><... | 387 | bash | <h1>How to extract directory path from file path?</h1>
<p>In Bash, if <code>VAR="/home/me/mydir/file.c"</code>, how do I get <code>"/home/me/mydir"</code>?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 156 | bash | # How to extract directory path from file path?
In Bash, if `VAR="/home/me/mydir/file.c"`, how do I get `"/home/me/mydir"`? | `dirname` and `basename` are the tools you're looking for for extracting path components:
```
$ VAR='/home/pax/file.c'
$ DIR="$(dirname "${VAR}")" ; FILE="$(basename "${VAR}")"
$ echo "[${DIR}] [${FILE}]"
[/home/pax] [file.c]
```
They're not internal `bash` commands but they are part of the POSIX standard - see [`dir... |
6697753 | Difference between single and double quotes in Bash | 963 | 2011-07-14 17:55:27 | <p>In Bash, what are the differences between single quotes (<code>''</code>) and double quotes (<code>""</code>)?</p>
| 475,900 | 318,760 | 2025-07-24 15:22:29 | 6,697,781 | 969 | 2011-07-14 17:57:44 | 120,808 | 2025-07-23 13:56:29 | https://stackoverflow.com/q/6697753 | https://stackoverflow.com/a/6697781 | <p>Single quotes won't interpolate anything, but double quotes will. For example: variables, backticks, certain <code>\</code> escapes, etc.</p>
<p>Example:</p>
<pre class="lang-bash prettyprint-override"><code>echo "$(echo "upg")"
</code></pre>
<p>Output:</p>
<pre class="lang-bash prettyprint-overr... | <p>Single quotes won't interpolate anything, but double quotes will. For example: variables, backticks, certain <code>\</code> escapes, etc.</p> <p>Example:</p> <pre class="lang-bash prettyprint-override"><code>echo "$(echo "upg")" </code></pre> <p>Output:</p> <pre class="lang-bash prettyprint-overr... | 387, 390, 430, 63342, 108300 | bash, double-quotes, quotes, shell, single-quotes | <h1>Difference between single and double quotes in Bash</h1>
<p>In Bash, what are the differences between single quotes (<code>''</code>) and double quotes (<code>""</code>)?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 157 | bash | # Difference between single and double quotes in Bash
In Bash, what are the differences between single quotes (`''`) and double quotes (`""`)? | Single quotes won't interpolate anything, but double quotes will. For example: variables, backticks, certain `\` escapes, etc.
Example:
```
echo "$(echo "upg")"
```
Output:
```
upg
```
And:
```
echo '$(echo "upg")'
```
Output:
```
$(echo "upg")
```
The Bash manual has this to say:
> [3.1.2.2 Single Quotes](ht... |
9146123 | Pretty print in MongoDB shell as default | 577 | 2012-02-05 01:19:52 | <p>Is there a way to tell Mongo to pretty print output? Currently, everything is output to a single line and it's difficult to read, especially with nested arrays and documents.</p>
| 171,965 | 791,406 | 2019-05-13 06:51:29 | 9,146,646 | 958 | 2012-02-05 03:19:23 | 125,816 | 2013-10-28 10:46:52 | https://stackoverflow.com/q/9146123 | https://stackoverflow.com/a/9146646 | <p>(<em>note: this is answer to original version of the question, which did not have requirements for "default"</em>)</p>
<p>You can ask it to be pretty.</p>
<pre><code>db.collection.find().pretty()
</code></pre>
| <p>(<em>note: this is answer to original version of the question, which did not have requirements for "default"</em>)</p> <p>You can ask it to be pretty.</p> <pre><code>db.collection.find().pretty() </code></pre> | 11225, 30073, 69521 | command-line-interface, mongodb, mongo-shell | <h1>Pretty print in MongoDB shell as default</h1>
<p>Is there a way to tell Mongo to pretty print output? Currently, everything is output to a single line and it's difficult to read, especially with nested arrays and documents.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 158 | bash | # Pretty print in MongoDB shell as default
Is there a way to tell Mongo to pretty print output? Currently, everything is output to a single line and it's difficult to read, especially with nested arrays and documents. | (*note: this is answer to original version of the question, which did not have requirements for "default"*)
You can ask it to be pretty.
```
db.collection.find().pretty()
``` |
428109 | Extract substring in Bash | 1,197 | 2009-01-09 13:53:22 | <p>Given a filename in the form <code>someletters_12345_moreleters.ext</code>, I want to extract the 5 digits and put them into a variable.</p>
<p>So to emphasize the point, I have a filename with x number of characters then a five digit sequence surrounded by a single underscore on either side then another set of x n... | 2,076,499 | 39,666 | 2025-04-29 08:09:40 | 428,118 | 947 | 2009-01-09 13:56:14 | 40,441 | 2015-11-04 22:51:55 | https://stackoverflow.com/q/428109 | https://stackoverflow.com/a/428118 | <p>Use <a href="http://www.manpagez.com/man/1/cut/" rel="noreferrer">cut</a>:</p>
<pre><code>echo 'someletters_12345_moreleters.ext' | cut -d'_' -f 2
</code></pre>
<p>More generic:</p>
<pre><code>INPUT='someletters_12345_moreleters.ext'
SUBSTRING=$(echo $INPUT| cut -d'_' -f 2)
echo $SUBSTRING
</code></pre>
| <p>Use <a href="http://www.manpagez.com/man/1/cut/" rel="noreferrer">cut</a>:</p> <pre><code>echo 'someletters_12345_moreleters.ext' | cut -d'_' -f 2 </code></pre> <p>More generic:</p> <pre><code>INPUT='someletters_12345_moreleters.ext' SUBSTRING=$(echo $INPUT| cut -d'_' -f 2) echo $SUBSTRING </code></pre> | 139, 387, 390, 4371 | bash, shell, string, substring | <h1>Extract substring in Bash</h1>
<p>Given a filename in the form <code>someletters_12345_moreleters.ext</code>, I want to extract the 5 digits and put them into a variable.</p>
<p>So to emphasize the point, I have a filename with x number of characters then a five digit sequence surrounded by a single underscore on ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 159 | bash | # Extract substring in Bash
Given a filename in the form `someletters_12345_moreleters.ext`, I want to extract the 5 digits and put them into a variable.
So to emphasize the point, I have a filename with x number of characters then a five digit sequence surrounded by a single underscore on either side then another se... | Use [cut](http://www.manpagez.com/man/1/cut/):
```
echo 'someletters_12345_moreleters.ext' | cut -d'_' -f 2
```
More generic:
```
INPUT='someletters_12345_moreleters.ext'
SUBSTRING=$(echo $INPUT| cut -d'_' -f 2)
echo $SUBSTRING
``` |
2764051 | How to join multiple lines of filenames into one with custom delimiter | 592 | 2010-05-04 09:09:40 | <p>How do I join the result of <code>ls -1</code> into a single line and <a href="https://en.wikipedia.org/wiki/Delimiter" rel="noreferrer">delimit</a> it with whatever I want?</p>
| 331,384 | 99,033 | 2024-11-12 00:58:32 | 6,539,865 | 944 | 2011-06-30 19:10:36 | 823,691 | 2023-02-19 20:44:14 | https://stackoverflow.com/q/2764051 | https://stackoverflow.com/a/6539865 | <p><code>paste -s -d</code> joins lines with a delimiter (e.g. <code>","</code>), and does not leave a trailing delimiter:</p>
<pre><code>ls -1 | paste -sd "," -
</code></pre>
| <p><code>paste -s -d</code> joins lines with a delimiter (e.g. <code>","</code>), and does not leave a trailing delimiter:</p> <pre><code>ls -1 | paste -sd "," - </code></pre> | 58, 139, 387, 390, 1357 | bash, linux, parsing, shell, string | <h1>How to join multiple lines of filenames into one with custom delimiter</h1>
<p>How do I join the result of <code>ls -1</code> into a single line and <a href="https://en.wikipedia.org/wiki/Delimiter" rel="noreferrer">delimit</a> it with whatever I want?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 160 | bash | # How to join multiple lines of filenames into one with custom delimiter
How do I join the result of `ls -1` into a single line and [delimit](https://en.wikipedia.org/wiki/Delimiter) it with whatever I want? | `paste -s -d` joins lines with a delimiter (e.g. `","`), and does not leave a trailing delimiter:
```
ls -1 | paste -sd "," -
``` |
4572153 | OS X: equivalent of Linux's wget | 673 | 2010-12-31 20:19:54 | <p>How can I do an HTTP GET from a Un*x shell script on a stock OS X system? (installing third-party software is not an option, for this has to run on a lot of different systems which I don't have control on).</p>
<p>For example if I start the Mercurial server locally doing a <em>hg serve</em>:</p>
<pre><code>... $ h... | 818,877 | 257,356 | 2022-10-29 16:41:32 | 4,572,158 | 943 | 2010-12-31 20:21:26 | 207,248 | 2022-10-29 16:41:32 | https://stackoverflow.com/q/4572153 | https://stackoverflow.com/a/4572158 | <p>The following native command will work:</p>
<p><code>curl http://127.0.0.1:8000 -o outfile</code></p>
<p>Note that <code>curl</code> does not follow redirects by default. To tell it to do so, add <code>-L</code> to the argument list.</p>
| <p>The following native command will work:</p> <p><code>curl http://127.0.0.1:8000 -o outfile</code></p> <p>Note that <code>curl</code> does not follow redirects by default. To tell it to do so, add <code>-L</code> to the argument list.</p> | 34, 369, 390, 6810 | http-get, macos, shell, unix | <h1>OS X: equivalent of Linux's wget</h1>
<p>How can I do an HTTP GET from a Un*x shell script on a stock OS X system? (installing third-party software is not an option, for this has to run on a lot of different systems which I don't have control on).</p>
<p>For example if I start the Mercurial server locally doing a ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 161 | bash | # OS X: equivalent of Linux's wget
How can I do an HTTP GET from a Un*x shell script on a stock OS X system? (installing third-party software is not an option, for this has to run on a lot of different systems which I don't have control on).
For example if I start the Mercurial server locally doing a *hg serve*:
```... | The following native command will work:
`curl http://127.0.0.1:8000 -o outfile`
Note that `curl` does not follow redirects by default. To tell it to do so, add `-L` to the argument list. |
394230 | How to detect the OS from a Bash script? | 841 | 2008-12-26 20:27:35 | <p>I would like to keep my <code>.bashrc</code> and <code>.bash_login</code> files in version control so that I can use them between all the computers I use. The problem is I have some OS specific aliases so I was looking for a way to determine if the script is running on Mac OS X, Linux or <a href="http://en... | 534,665 | 19,839 | 2025-09-18 02:27:09 | 8,597,411 | 938 | 2011-12-21 22:46:47 | 265,521 | 2020-05-05 12:08:57 | https://stackoverflow.com/q/394230 | https://stackoverflow.com/a/8597411 | <p>I think the following should work. I'm not sure about <code>win32</code> though.</p>
<pre><code>if [[ "$OSTYPE" == "linux-gnu"* ]]; then
# ...
elif [[ "$OSTYPE" == "darwin"* ]]; then
# Mac OSX
elif [[ "$OSTYPE" == "cygwin" ]]; then
# POSIX compatibility layer and Linux environment emulation ... | <p>I think the following should work. I'm not sure about <code>win32</code> though.</p> <pre><code>if [[ "$OSTYPE" == "linux-gnu"* ]]; then # ... elif [[ "$OSTYPE" == "darwin"* ]]; then # Mac OSX elif [[ "$OSTYPE" == "cygwin" ]]; then # POSIX compatibility layer and Linux environment emulation ... | 387, 97338 | bash, os-detection | <h1>How to detect the OS from a Bash script?</h1>
<p>I would like to keep my <code>.bashrc</code> and <code>.bash_login</code> files in version control so that I can use them between all the computers I use. The problem is I have some OS specific aliases so I was looking for a way to determine if the script is running ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 162 | bash | # How to detect the OS from a Bash script?
I would like to keep my `.bashrc` and `.bash_login` files in version control so that I can use them between all the computers I use. The problem is I have some OS specific aliases so I was looking for a way to determine if the script is running on Mac OS X, Linux or [Cygwin](... | I think the following should work. I'm not sure about `win32` though.
```
if [[ "$OSTYPE" == "linux-gnu"* ]]; then
# ...
elif [[ "$OSTYPE" == "darwin"* ]]; then
# Mac OSX
elif [[ "$OSTYPE" == "cygwin" ]]; then
# POSIX compatibility layer and Linux environment emulation for Windows
elif [[ "$OST... |
320509 | Is it possible to open a Windows Explorer window from PowerShell? | 449 | 2008-11-26 12:19:08 | <p>I'm sure this must be possible, but I can't find out how to do it.</p>
<p>Any clues?</p>
| 219,957 | 1,088,682 | 2024-09-26 08:00:43 | 321,092 | 932 | 2008-11-26 15:25:25 | 1,358 | 2023-09-12 13:14:33 | https://stackoverflow.com/q/320509 | https://stackoverflow.com/a/321092 | <p>Use:</p>
<pre><code>ii .
</code></pre>
<p>which is short for</p>
<pre><code>Invoke-Item .
</code></pre>
<p>The dot can be substituted with any path.</p>
| <p>Use:</p> <pre><code>ii . </code></pre> <p>which is short for</p> <pre><code>Invoke-Item . </code></pre> <p>The dot can be substituted with any path.</p> | 526, 638 | explorer, powershell | <h1>Is it possible to open a Windows Explorer window from PowerShell?</h1>
<p>I'm sure this must be possible, but I can't find out how to do it.</p>
<p>Any clues?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 163 | bash | # Is it possible to open a Windows Explorer window from PowerShell?
I'm sure this must be possible, but I can't find out how to do it.
Any clues? | Use:
```
ii .
```
which is short for
```
Invoke-Item .
```
The dot can be substituted with any path. |
3980668 | How to get a password from a shell script without echoing | 647 | 2010-10-20 17:33:28 | <p>I have a script that automates a process that needs access to a password-protected system. The system is accessed via a command-line program that accepts the user password as an argument.</p>
<p>I would like to prompt the user to type in their password, assign it to a shell variable, and then use that variable to co... | 685,404 | 220,826 | 2023-12-05 00:25:11 | 3,980,904 | 930 | 2010-10-20 18:04:18 | 480,767 | 2023-04-02 18:40:39 | https://stackoverflow.com/q/3980668 | https://stackoverflow.com/a/3980904 | <p>Here is another way to do it:</p>
<pre><code>#!/bin/bash
# Read Password
echo -n Password:
read -s password
echo
# Run Command
echo $password
</code></pre>
<p>The <code>read -s</code> will turn off echo for you. Just replace the <code>echo</code> on the last line with the command you want to run.</p>
<p>In some she... | <p>Here is another way to do it:</p> <pre><code>#!/bin/bash # Read Password echo -n Password: read -s password echo # Run Command echo $password </code></pre> <p>The <code>read -s</code> will turn off echo for you. Just replace the <code>echo</code> on the last line with the command you want to run.</p> <p>In some she... | 387, 390, 531, 10327 | bash, scripting, sh, shell | <h1>How to get a password from a shell script without echoing</h1>
<p>I have a script that automates a process that needs access to a password-protected system. The system is accessed via a command-line program that accepts the user password as an argument.</p>
<p>I would like to prompt the user to type in their passwo... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 164 | bash | # How to get a password from a shell script without echoing
I have a script that automates a process that needs access to a password-protected system. The system is accessed via a command-line program that accepts the user password as an argument.
I would like to prompt the user to type in their password, assign it t... | Here is another way to do it:
```
#!/bin/bash
# Read Password
echo -n Password:
read -s password
echo
# Run Command
echo $password
```
The `read -s` will turn off echo for you. Just replace the `echo` on the last line with the command you want to run.
In some shells (e.g. Bash) [`read`](https://linuxcommand.org/lc3... |
58032631 | Why powershell does not run Angular commands? | 367 | 2019-09-20 17:11:21 | <p>I have started to learn Angular but I note that powershell in Windows gives me an error whenever I make an angular command like:</p>
<pre><code>ng new new-app
</code></pre>
<p>or</p>
<pre><code>ng serve
</code></pre>
<p>this is the error what I got:</p>
<pre><code>ng : File C:\Users\< username >\AppData\R... | 513,662 | 11,307,065 | 2024-06-21 06:54:51 | 58,044,573 | 913 | 2019-09-21 22:23:06 | 11,307,065 | 2020-02-11 23:31:49 | https://stackoverflow.com/q/58032631 | https://stackoverflow.com/a/58044573 | <p>Remove <code>ng.ps1</code> from the directory <code>C:\Users\%username%\AppData\Roaming\npm\</code> then try clearing the npm cache at <code>C:\Users\%username%\AppData\Roaming\npm-cache\</code> </p>
| <p>Remove <code>ng.ps1</code> from the directory <code>C:\Users\%username%\AppData\Roaming\npm\</code> then try clearing the npm cache at <code>C:\Users\%username%\AppData\Roaming\npm-cache\</code> </p> | 3, 526, 117722, 125866 | angular, angular-cli, javascript, powershell | <h1>Why powershell does not run Angular commands?</h1>
<p>I have started to learn Angular but I note that powershell in Windows gives me an error whenever I make an angular command like:</p>
<pre><code>ng new new-app
</code></pre>
<p>or</p>
<pre><code>ng serve
</code></pre>
<p>this is the error what I got:</p>
<pr... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 165 | bash | # Why powershell does not run Angular commands?
I have started to learn Angular but I note that powershell in Windows gives me an error whenever I make an angular command like:
```
ng new new-app
```
or
```
ng serve
```
this is the error what I got:
```
ng : File C:\Users\< username >\AppData\Roaming\npm\ng.ps1 c... | Remove `ng.ps1` from the directory `C:\Users\%username%\AppData\Roaming\npm\` then try clearing the npm cache at `C:\Users\%username%\AppData\Roaming\npm-cache\` |
39296472 | How to check if an environment variable exists and get its value? | 566 | 2016-09-02 15:55:13 | <p>I am writing a shell script. In this shell script, I am have a variable that either takes a default value, or the value of an environment variable. However, the environment variable doesn't have to be present.</p>
<p>For instance, assume, before running the script, I perform the following operation:</p>
<pre><code... | 909,254 | 2,865,564 | 2024-09-08 14:26:38 | 39,296,583 | 909 | 2016-09-02 16:02:25 | 6,658,477 | 2018-05-14 17:26:05 | https://stackoverflow.com/q/39296472 | https://stackoverflow.com/a/39296583 | <p><code>[ -z "${DEPLOY_ENV}" ]</code> checks whether <code>DEPLOY_ENV</code> has length equal to zero. So you could run:</p>
<pre><code>if [[ -z "${DEPLOY_ENV}" ]]; then
MY_SCRIPT_VARIABLE="Some default value because DEPLOY_ENV is undefined"
else
MY_SCRIPT_VARIABLE="${DEPLOY_ENV}"
fi
# or using a short-hand vers... | <p><code>[ -z "${DEPLOY_ENV}" ]</code> checks whether <code>DEPLOY_ENV</code> has length equal to zero. So you could run:</p> <pre><code>if [[ -z "${DEPLOY_ENV}" ]]; then MY_SCRIPT_VARIABLE="Some default value because DEPLOY_ENV is undefined" else MY_SCRIPT_VARIABLE="${DEPLOY_ENV}" fi # or using a short-hand vers... | 387, 390 | bash, shell | <h1>How to check if an environment variable exists and get its value?</h1>
<p>I am writing a shell script. In this shell script, I am have a variable that either takes a default value, or the value of an environment variable. However, the environment variable doesn't have to be present.</p>
<p>For instance, assume, be... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 166 | bash | # How to check if an environment variable exists and get its value?
I am writing a shell script. In this shell script, I am have a variable that either takes a default value, or the value of an environment variable. However, the environment variable doesn't have to be present.
For instance, assume, before running the... | `[ -z "${DEPLOY_ENV}" ]` checks whether `DEPLOY_ENV` has length equal to zero. So you could run:
```
if [[ -z "${DEPLOY_ENV}" ]]; then
MY_SCRIPT_VARIABLE="Some default value because DEPLOY_ENV is undefined"
else
MY_SCRIPT_VARIABLE="${DEPLOY_ENV}"
fi
# or using a short-hand version
[[ -z "${DEPLOY_ENV}" ]] && MyV... |
44435697 | Change the default terminal in Visual Studio Code | 518 | 2017-06-08 12:23:15 | <p>I am using Visual Studio Code on my Windows 10 PC. I want to change my default terminal from Windows <a href="https://en.wikipedia.org/wiki/PowerShell" rel="noreferrer">PowerShell</a> to <a href="https://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="noreferrer">Bash</a> on <a href="https://en.wikipedia.org/wiki/... | 674,018 | 6,735,912 | 2025-06-04 08:42:11 | 45,899,693 | 908 | 2017-08-26 21:10:09 | 2,535,344 | 2023-08-11 21:42:19 | https://stackoverflow.com/q/44435697 | https://stackoverflow.com/a/45899693 | <p>You can also select your default terminal by pressing <kbd>F1</kbd> in Visual Studio Code and typing/selecting <strong><code>Terminal: Select Default Profile</code></strong> (or <strong><code>Terminal: Select Default Shell</code></strong> in older Visual Studio Code versions).</p>
<p><img src="https://i.sstatic.net/... | <p>You can also select your default terminal by pressing <kbd>F1</kbd> in Visual Studio Code and typing/selecting <strong><code>Terminal: Select Default Profile</code></strong> (or <strong><code>Terminal: Select Default Shell</code></strong> in older Visual Studio Code versions).</p> <p><img src="https://i.sstatic.net/... | 387, 391, 526, 2631, 111608 | bash, cmd, powershell, terminal, visual-studio-code | <h1>Change the default terminal in Visual Studio Code</h1>
<p>I am using Visual Studio Code on my Windows 10 PC. I want to change my default terminal from Windows <a href="https://en.wikipedia.org/wiki/PowerShell" rel="noreferrer">PowerShell</a> to <a href="https://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="nore... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 167 | bash | # Change the default terminal in Visual Studio Code
I am using Visual Studio Code on my Windows 10 PC. I want to change my default terminal from Windows [PowerShell](https://en.wikipedia.org/wiki/PowerShell) to [Bash](https://en.wikipedia.org/wiki/Bash_%28Unix_shell%29) on [Ubuntu](https://en.wikipedia.org/wiki/Ubuntu... | You can also select your default terminal by pressing `F1` in Visual Studio Code and typing/selecting **`Terminal: Select Default Profile`** (or **`Terminal: Select Default Shell`** in older Visual Studio Code versions).
Older:
![Terminal Selection](https://i.... |
31579509 | Can pm2 run an 'npm start' script | 452 | 2015-07-23 06:18:02 | <p>Is there a way for pm2 to run an npm start script or do you just have to run <code>pm2 start app.js</code></p>
<p>So in development</p>
<pre><code>npm start
</code></pre>
<p>Then in production with pm2 you would run something like</p>
<pre><code>pm2 start 'npm start'
</code></pre>
<p>There is an equivalent way to do... | 685,132 | 3,709,775 | 2025-07-24 07:45:14 | 37,775,318 | 904 | 2016-06-12 14:23:05 | 3,314,614 | 2020-06-14 12:38:30 | https://stackoverflow.com/q/31579509 | https://stackoverflow.com/a/37775318 | <p>PM2 now supports npm start:</p>
<pre><code>pm2 start npm -- start
</code></pre>
<p>To assign a name to the PM2 process, use the <code>--name</code> option:</p>
<pre><code>pm2 start npm --name "app name" -- start
</code></pre>
| <p>PM2 now supports npm start:</p> <pre><code>pm2 start npm -- start </code></pre> <p>To assign a name to the PM2 process, use the <code>--name</code> option:</p> <pre><code>pm2 start npm --name "app name" -- start </code></pre> | 390, 46426, 61387, 99738 | node.js, npm, pm2, shell | <h1>Can pm2 run an 'npm start' script</h1>
<p>Is there a way for pm2 to run an npm start script or do you just have to run <code>pm2 start app.js</code></p>
<p>So in development</p>
<pre><code>npm start
</code></pre>
<p>Then in production with pm2 you would run something like</p>
<pre><code>pm2 start 'npm start'
</code... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 168 | bash | # Can pm2 run an 'npm start' script
Is there a way for pm2 to run an npm start script or do you just have to run `pm2 start app.js`
So in development
```
npm start
```
Then in production with pm2 you would run something like
```
pm2 start 'npm start'
```
There is an equivalent way to do this in `forever`:
```
fo... | PM2 now supports npm start:
```
pm2 start npm -- start
```
To assign a name to the PM2 process, use the `--name` option:
```
pm2 start npm --name "app name" -- start
``` |
669452 | Are double square brackets [[ ]] preferable over single square brackets [ ] in Bash? | 958 | 2009-03-21 15:28:45 | <p>A coworker claimed recently in a code review that the <code>[[ ]]</code> construct is to be preferred over <code>[ ]</code> in constructs like</p>
<pre><code>if [ "`id -nu`" = "$someuser" ] ; then
echo "I love you madly, $someuser"
fi
</code></pre>
<p>He couldn't provide a rational... | 441,996 | 10,888 | 2025-08-04 04:52:53 | 669,486 | 900 | 2009-03-21 15:44:09 | 34,509 | 2025-03-09 02:12:13 | https://stackoverflow.com/q/669452 | https://stackoverflow.com/a/669486 | <p><code>[[</code> has fewer surprises and is generally safer to use. But it is not portable - POSIX doesn't specify what it does and only some shells support it (beside bash, I heard ksh supports it too). For example, you can do</p>
<pre><code>[[ -e $b ]]
</code></pre>
<p>to test whether a file exists. But with <code>... | <p><code>[[</code> has fewer surprises and is generally safer to use. But it is not portable - POSIX doesn't specify what it does and only some shells support it (beside bash, I heard ksh supports it too). For example, you can do</p> <pre><code>[[ -e $b ]] </code></pre> <p>to test whether a file exists. But with <code>... | 367, 387, 2773 | bash, if-statement, syntax | <h1>Are double square brackets [[ ]] preferable over single square brackets [ ] in Bash?</h1>
<p>A coworker claimed recently in a code review that the <code>[[ ]]</code> construct is to be preferred over <code>[ ]</code> in constructs like</p>
<pre><code>if [ "`id -nu`" = "$someuser" ] ; then
e... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 169 | bash | # Are double square brackets [[ ]] preferable over single square brackets [ ] in Bash?
A coworker claimed recently in a code review that the `[[ ]]` construct is to be preferred over `[ ]` in constructs like
```
if [ "`id -nu`" = "$someuser" ] ; then
echo "I love you madly, $someuser"
fi
```
He couldn't provide... | `[[` has fewer surprises and is generally safer to use. But it is not portable - POSIX doesn't specify what it does and only some shells support it (beside bash, I heard ksh supports it too). For example, you can do
```
[[ -e $b ]]
```
to test whether a file exists. But with `[`, you have to wrap `$b` in double-quote... |
56839307 | Adding Git-Bash to the new Windows Terminal | 606 | 2019-07-01 16:38:57 | <p>I'm trying to add a new terminal (Git Bash) to the new Windows Terminal. However, I can't get it to work.</p>
<p>I tried changing the <code>commandline</code> property in the <code>profiles</code> array to <code>git-bash.exe</code> but no luck.</p>
<p>Does anyone have an idea how to get this to work?</p>
| 384,671 | 5,253,155 | 2025-05-12 19:40:17 | 57,369,284 | 891 | 2019-08-06 05:09:44 | 242,042 | 2024-01-05 06:12:04 | https://stackoverflow.com/q/56839307 | https://stackoverflow.com/a/57369284 | <h1>Overview</h1>
<ol>
<li>Open settings with <kbd>Ctrl</kbd>+<kbd>,</kbd></li>
<li>You'll want to append one of the profiles options below (depending on what version of git you have installed) to the <code>"list":</code> portion of the <code>settings.json</code> file:</li>
</ol>
<p><a href="https://i.sstatic... | <h1>Overview</h1> <ol> <li>Open settings with <kbd>Ctrl</kbd>+<kbd>,</kbd></li> <li>You'll want to append one of the profiles options below (depending on what version of git you have installed) to the <code>"list":</code> portion of the <code>settings.json</code> file:</li> </ol> <p><a href="https://i.sstatic... | 61874, 138178 | git-bash, windows-terminal | <h1>Adding Git-Bash to the new Windows Terminal</h1>
<p>I'm trying to add a new terminal (Git Bash) to the new Windows Terminal. However, I can't get it to work.</p>
<p>I tried changing the <code>commandline</code> property in the <code>profiles</code> array to <code>git-bash.exe</code> but no luck.</p>
<p>Does anyone ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 170 | bash | # Adding Git-Bash to the new Windows Terminal
I'm trying to add a new terminal (Git Bash) to the new Windows Terminal. However, I can't get it to work.
I tried changing the `commandline` property in the `profiles` array to `git-bash.exe` but no luck.
Does anyone have an idea how to get this to work? | # Overview
1. Open settings with `Ctrl`+`,`
2. You'll want to append one of the profiles options below (depending on what version of git you have installed) to the `"list":` portion of the `settings.json` file:
[](https://i.sstatic.net/... |
43158140 | Way to create multiline comments in Bash? | 495 | 2017-04-01 14:33:08 | <p>I have recently started studying shell script and I'd like to be able to comment out a set of lines in a shell script. I mean like it is in case of C/Java :</p>
<pre><code>/* comment1
comment2
comment3
*/
</code></pre>
<p>How could I do that?</p>
| 480,418 | 7,310,822 | 2025-07-04 14:45:16 | 43,158,193 | 879 | 2017-04-01 14:38:15 | 7,022,822 | 2019-01-13 18:02:43 | https://stackoverflow.com/q/43158140 | https://stackoverflow.com/a/43158193 | <p>Use <code>: '</code> to open and <code>'</code> to close.</p>
<p>For example:</p>
<pre><code>: '
This is a
very neat comment
in bash
'
</code></pre>
| <p>Use <code>: '</code> to open and <code>'</code> to close.</p> <p>For example:</p> <pre><code>: ' This is a very neat comment in bash ' </code></pre> | 390, 1966, 10941 | comments, multiline, shell | <h1>Way to create multiline comments in Bash?</h1>
<p>I have recently started studying shell script and I'd like to be able to comment out a set of lines in a shell script. I mean like it is in case of C/Java :</p>
<pre><code>/* comment1
comment2
comment3
*/
</code></pre>
<p>How could I do that?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 171 | bash | # Way to create multiline comments in Bash?
I have recently started studying shell script and I'd like to be able to comment out a set of lines in a shell script. I mean like it is in case of C/Java :
```
/* comment1
comment2
comment3
*/
```
How could I do that? | Use `: '` to open and `'` to close.
For example:
```
: '
This is a
very neat comment
in bash
'
``` |
42950501 | Delete node_modules folder recursively from a specified path using command line | 388 | 2017-03-22 11:34:57 | <p>I have multiple npm projects saved in a local directory. Now I want to take backup of my projects without the <em><a href="https://stackoverflow.com/questions/63294260/what-is-the-purpose-of-the-node-modules-folder">node_modules</a></em> folder, as it is taking a lot of space and can also be retrieved any time using... | 170,199 | 5,007,098 | 2025-11-06 14:54:49 | 43,561,012 | 874 | 2017-04-22 15:29:02 | 1,293,700 | 2022-11-12 00:30:08 | https://stackoverflow.com/q/42950501 | https://stackoverflow.com/a/43561012 | <p>Print out a list of directories to be deleted:</p>
<pre class="lang-none prettyprint-override"><code>find . -name 'node_modules' -type d -prune
</code></pre>
<p>Delete directories from the current working directory:</p>
<pre class="lang-none prettyprint-override"><code>find . -name 'node_modules' -type d -prune -exe... | <p>Print out a list of directories to be deleted:</p> <pre class="lang-none prettyprint-override"><code>find . -name 'node_modules' -type d -prune </code></pre> <p>Delete directories from the current working directory:</p> <pre class="lang-none prettyprint-override"><code>find . -name 'node_modules' -type d -prune -exe... | 369, 387, 11225, 78230 | bash, command-line-interface, macos, node-modules | <h1>Delete node_modules folder recursively from a specified path using command line</h1>
<p>I have multiple npm projects saved in a local directory. Now I want to take backup of my projects without the <em><a href="https://stackoverflow.com/questions/63294260/what-is-the-purpose-of-the-node-modules-folder">node_modules... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 172 | bash | # Delete node_modules folder recursively from a specified path using command line
I have multiple npm projects saved in a local directory. Now I want to take backup of my projects without the *[node_modules](https://stackoverflow.com/questions/63294260/what-is-the-purpose-of-the-node-modules-folder)* folder, as it is ... | Print out a list of directories to be deleted:
```
find . -name 'node_modules' -type d -prune
```
Delete directories from the current working directory:
```
find . -name 'node_modules' -type d -prune -exec rm -rf '{}' +
```
---
Alternatively you can use [trash](https://github.com/sindresorhus/trash-cli) (`brew ins... |
12667797 | Using cURL to upload POST data with files | 604 | 2012-10-01 05:10:56 | <p>I would like to use cURL to not only send data parameters in HTTP POST but to also upload files with specific form name. How should I go about doing that ?</p>
<p>HTTP Post parameters:</p>
<p>userid = 12345
filecomment = This is an image file</p>
<p>HTTP File upload:
File location = /home/user1/Desktop/test.jpg
F... | 1,070,605 | 476,467 | 2024-07-15 11:49:02 | 12,667,839 | 871 | 2012-10-01 05:18:26 | 791,265 | 2015-11-05 12:44:57 | https://stackoverflow.com/q/12667797 | https://stackoverflow.com/a/12667839 | <p>You need to use the <code>-F</code> option:<br>
<code>-F/--form <name=content> Specify HTTP multipart POST data (H)</code></p>
<p>Try this:</p>
<pre><code>curl \
-F "userid=1" \
-F "filecomment=This is an image file" \
-F "image=@/home/user1/Desktop/test.jpg" \
localhost/uploader.php
</code></pre>
| <p>You need to use the <code>-F</code> option:<br> <code>-F/--form <name=content> Specify HTTP multipart POST data (H)</code></p> <p>Try this:</p> <pre><code>curl \ -F "userid=1" \ -F "filecomment=This is an image file" \ -F "image=@/home/user1/Desktop/test.jpg" \ localhost/uploader.php </code></pre> | 390, 904, 1554, 4209, 5310 | curl, file, file-upload, post, shell | <h1>Using cURL to upload POST data with files</h1>
<p>I would like to use cURL to not only send data parameters in HTTP POST but to also upload files with specific form name. How should I go about doing that ?</p>
<p>HTTP Post parameters:</p>
<p>userid = 12345
filecomment = This is an image file</p>
<p>HTTP File upl... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 173 | bash | # Using cURL to upload POST data with files
I would like to use cURL to not only send data parameters in HTTP POST but to also upload files with specific form name. How should I go about doing that ?
HTTP Post parameters:
userid = 12345
filecomment = This is an image file
HTTP File upload:
File location = /home/use... | You need to use the `-F` option:
`-F/--form <name=content> Specify HTTP multipart POST data (H)`
Try this:
```
curl \
-F "userid=1" \
-F "filecomment=This is an image file" \
-F "image=@/home/user1/Desktop/test.jpg" \
localhost/uploader.php
``` |
2920416 | ./configure : /bin/sh^M : bad interpreter | 453 | 2010-05-27 10:49:52 | <p>I've been trying to install lpng142 on my fed 12 system. Seems like a problem to me. I get this error</p>
<pre><code>[root@localhost lpng142]# ./configure
bash: ./configure: /bin/sh^M: bad interpreter: No such file or directory
[root@localhost lpng142]#
</code></pre>
<p>How do I fix this? The <code>/etc/fstab</co... | 612,539 | 348,862 | 2022-10-12 15:17:51 | 5,514,351 | 871 | 2011-04-01 13:53:41 | 687,701 | 2018-03-30 20:17:38 | https://stackoverflow.com/q/2920416 | https://stackoverflow.com/a/5514351 | <p>To fix, open your script with vi or vim and enter in vi command mode (key <KBD>Esc</KBD>), then type this:</p>
<pre><code>:set fileformat=unix
</code></pre>
<p>Finally save it</p>
<p><code>:x!</code> or <code>:wq!</code></p>
| <p>To fix, open your script with vi or vim and enter in vi command mode (key <KBD>Esc</KBD>), then type this:</p> <pre><code>:set fileformat=unix </code></pre> <p>Finally save it</p> <p><code>:x!</code> or <code>:wq!</code></p> | 58, 387, 390, 3705, 14899 | bash, carriage-return, linux, newline, shell | <h1>./configure : /bin/sh^M : bad interpreter</h1>
<p>I've been trying to install lpng142 on my fed 12 system. Seems like a problem to me. I get this error</p>
<pre><code>[root@localhost lpng142]# ./configure
bash: ./configure: /bin/sh^M: bad interpreter: No such file or directory
[root@localhost lpng142]#
</code></p... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 174 | bash | # ./configure : /bin/sh^M : bad interpreter
I've been trying to install lpng142 on my fed 12 system. Seems like a problem to me. I get this error
```
[root@localhost lpng142]# ./configure
bash: ./configure: /bin/sh^M: bad interpreter: No such file or directory
[root@localhost lpng142]#
```
How do I fix this? The `/e... | To fix, open your script with vi or vim and enter in vi command mode (key `Esc`), then type this:
```
:set fileformat=unix
```
Finally save it
`:x!` or `:wq!` |
10610327 | Delete all local Git branches | 770 | 2012-05-15 23:45:47 | <p>I follow a development process where I create a new local branch for every new feature or story card. When finished I merge the branch into <em>master</em> and then push.</p>
<p>What tends to happen over time due to a combination of laziness or forgetfulness, is that I end up with a large list of local branches, som... | 743,284 | 629,555 | 2025-10-02 14:48:43 | 10,610,669 | 870 | 2012-05-16 00:43:24 | 1,286,639 | 2022-07-19 10:18:53 | https://stackoverflow.com/q/10610327 | https://stackoverflow.com/a/10610669 | <p>The 'git branch -d' subcommand can delete more than one branch. So, simplifying @sblom's answer but adding a critical xargs:</p>
<pre><code>git branch -D `git branch --merged | grep -v \* | xargs`
</code></pre>
<p>or, further simplified to:</p>
<pre><code>git branch --merged | grep -v \* | xargs git branch -D
</co... | <p>The 'git branch -d' subcommand can delete more than one branch. So, simplifying @sblom's answer but adding a critical xargs:</p> <pre><code>git branch -D `git branch --merged | grep -v \* | xargs` </code></pre> <p>or, further simplified to:</p> <pre><code>git branch --merged | grep -v \* | xargs git branch -D </co... | 119, 387, 456, 549, 1271 | bash, git, grep, ubuntu, version-control | <h1>Delete all local Git branches</h1>
<p>I follow a development process where I create a new local branch for every new feature or story card. When finished I merge the branch into <em>master</em> and then push.</p>
<p>What tends to happen over time due to a combination of laziness or forgetfulness, is that I end up w... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 175 | bash | # Delete all local Git branches
I follow a development process where I create a new local branch for every new feature or story card. When finished I merge the branch into *master* and then push.
What tends to happen over time due to a combination of laziness or forgetfulness, is that I end up with a large list of lo... | The 'git branch -d' subcommand can delete more than one branch. So, simplifying @sblom's answer but adding a critical xargs:
```
git branch -D `git branch --merged | grep -v \* | xargs`
```
or, further simplified to:
```
git branch --merged | grep -v \* | xargs git branch -D
```
Importantly, as [noted by @AndrewC](... |
2664740 | Extract file basename without path and extension in bash | 490 | 2010-04-19 01:25:28 | <p>Given file names like these:</p>
<pre><code>/the/path/foo.txt
bar.txt
</code></pre>
<p>I hope to get:</p>
<pre><code>foo
bar
</code></pre>
<p>Why this doesn't work?</p>
<pre><code>#!/bin/bash
fullfile=$1
fname=$(basename $fullfile)
fbname=${fname%.*}
echo $fbname
</code></pre>
<p>What's the right way to do it... | 745,989 | 67,405 | 2023-07-06 21:40:37 | 2,664,746 | 870 | 2010-04-19 01:27:14 | 131,527 | 2020-01-10 07:52:19 | https://stackoverflow.com/q/2664740 | https://stackoverflow.com/a/2664746 | <p>You don't have to call the external <code>basename</code> command. Instead, you could use the following commands:</p>
<pre><code>$ s=/the/path/foo.txt
$ echo "${s##*/}"
foo.txt
$ s=${s##*/}
$ echo "${s%.txt}"
foo
$ echo "${s%.*}"
foo
</code></pre>
<p>Note that this solution should work in all recent (<em>post 2004... | <p>You don't have to call the external <code>basename</code> command. Instead, you could use the following commands:</p> <pre><code>$ s=/the/path/foo.txt $ echo "${s##*/}" foo.txt $ s=${s##*/} $ echo "${s%.txt}" foo $ echo "${s%.*}" foo </code></pre> <p>Note that this solution should work in all recent (<em>post 2004... | 34, 58, 387, 1062 | bash, filenames, linux, unix | <h1>Extract file basename without path and extension in bash</h1>
<p>Given file names like these:</p>
<pre><code>/the/path/foo.txt
bar.txt
</code></pre>
<p>I hope to get:</p>
<pre><code>foo
bar
</code></pre>
<p>Why this doesn't work?</p>
<pre><code>#!/bin/bash
fullfile=$1
fname=$(basename $fullfile)
fbname=${fnam... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 176 | bash | # Extract file basename without path and extension in bash
Given file names like these:
```
/the/path/foo.txt
bar.txt
```
I hope to get:
```
foo
bar
```
Why this doesn't work?
```
#!/bin/bash
fullfile=$1
fname=$(basename $fullfile)
fbname=${fname%.*}
echo $fbname
```
What's the right way to do it? | You don't have to call the external `basename` command. Instead, you could use the following commands:
```
$ s=/the/path/foo.txt
$ echo "${s##*/}"
foo.txt
$ s=${s##*/}
$ echo "${s%.txt}"
foo
$ echo "${s%.*}"
foo
```
Note that this solution should work in all recent (*post 2004*) *POSIX* compliant shells, (e.g. `bash`... |
3427872 | What's the difference between [ and [[ in Bash? | 584 | 2010-08-06 21:18:21 | <p>I looked at bash man page and the <code>[[</code> says it uses Conditional Expressions. Then I looked at Conditional Expressions section and it lists the same operators as <code>test</code> (and <code>[</code>).</p>
<p>So I wonder, what is the difference between <code>[</code> and <code>[[</code> in Bash?</p>
| 268,067 | 257,942 | 2024-03-30 19:27:33 | 3,427,931 | 869 | 2010-08-06 21:29:08 | 68,587 | 2017-10-12 15:20:59 | https://stackoverflow.com/q/3427872 | https://stackoverflow.com/a/3427931 | <p><code>[[</code> is bash's improvement to the <code>[</code> command. It has several enhancements that make it a better choice if you write scripts that target bash. My favorites are:</p>
<ol>
<li><p>It is a syntactical feature of the shell, so it has some special behavior that <code>[</code> doesn't have. You no lo... | <p><code>[[</code> is bash's improvement to the <code>[</code> command. It has several enhancements that make it a better choice if you write scripts that target bash. My favorites are:</p> <ol> <li><p>It is a syntactical feature of the shell, so it has some special behavior that <code>[</code> doesn't have. You no lo... | 387 | bash | <h1>What's the difference between [ and [[ in Bash?</h1>
<p>I looked at bash man page and the <code>[[</code> says it uses Conditional Expressions. Then I looked at Conditional Expressions section and it lists the same operators as <code>test</code> (and <code>[</code>).</p>
<p>So I wonder, what is the difference betw... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 177 | bash | # What's the difference between [ and [[ in Bash?
I looked at bash man page and the `[[` says it uses Conditional Expressions. Then I looked at Conditional Expressions section and it lists the same operators as `test` (and `[`).
So I wonder, what is the difference between `[` and `[[` in Bash? | `[[` is bash's improvement to the `[` command. It has several enhancements that make it a better choice if you write scripts that target bash. My favorites are:
1. It is a syntactical feature of the shell, so it has some special behavior that `[` doesn't have. You no longer have to quote variables like mad because `[[... |
41618766 | Powershell Invoke-WebRequest Fails with SSL/TLS Secure Channel | 421 | 2017-01-12 16:52:33 | <p>I'm trying to execute this powershell command</p>
<p><code>Invoke-WebRequest -Uri https://apod.nasa.gov/apod/</code></p>
<p>and I get this error. <em>"Invoke-WebRequest : The request was aborted: Could not create SSL/TLS secure channel."</em> https requests appear to work ("<a href="https://google.com" rel="noref... | 493,191 | 118,889 | 2021-03-13 13:27:02 | 41,618,979 | 869 | 2017-01-12 17:03:45 | 1,530,987 | 2017-01-12 17:03:45 | https://stackoverflow.com/q/41618766 | https://stackoverflow.com/a/41618979 | <p>try using this one</p>
<pre><code>[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
Invoke-WebRequest -Uri https://apod.nasa.gov/apod/
</code></pre>
| <p>try using this one</p> <pre><code>[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12 Invoke-WebRequest -Uri https://apod.nasa.gov/apod/ </code></pre> | 526, 641 | powershell, ssl | <h1>Powershell Invoke-WebRequest Fails with SSL/TLS Secure Channel</h1>
<p>I'm trying to execute this powershell command</p>
<p><code>Invoke-WebRequest -Uri https://apod.nasa.gov/apod/</code></p>
<p>and I get this error. <em>"Invoke-WebRequest : The request was aborted: Could not create SSL/TLS secure channel."</em> ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 178 | bash | # Powershell Invoke-WebRequest Fails with SSL/TLS Secure Channel
I'm trying to execute this powershell command
`Invoke-WebRequest -Uri https://apod.nasa.gov/apod/`
and I get this error. *"Invoke-WebRequest : The request was aborted: Could not create SSL/TLS secure channel."* https requests appear to work ("<https://... | try using this one
```
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
Invoke-WebRequest -Uri https://apod.nasa.gov/apod/
``` |
4749330 | How to test if string exists in file with Bash? | 463 | 2011-01-20 15:55:31 | <p>I have a file that contains directory names:</p>
<p><code>my_list.txt</code> :</p>
<pre><code>/tmp
/var/tmp
</code></pre>
<p>I'd like to check in Bash before I'll add a directory name if that name already exists in the file.</p>
| 914,377 | 410,999 | 2020-12-09 21:08:49 | 4,749,368 | 868 | 2011-01-20 15:58:40 | 14,637 | 2019-09-07 18:00:32 | https://stackoverflow.com/q/4749330 | https://stackoverflow.com/a/4749368 | <pre><code>grep -Fxq "$FILENAME" my_list.txt
</code></pre>
<p>The exit status is 0 (true) if the name was found, 1 (false) if not, so:</p>
<pre><code>if grep -Fxq "$FILENAME" my_list.txt
then
# code if found
else
# code if not found
fi
</code></pre>
<h3>Explanation</h3>
<p>Here are the relev... | <pre><code>grep -Fxq "$FILENAME" my_list.txt </code></pre> <p>The exit status is 0 (true) if the name was found, 1 (false) if not, so:</p> <pre><code>if grep -Fxq "$FILENAME" my_list.txt then # code if found else # code if not found fi </code></pre> <h3>Explanation</h3> <p>Here are the relev... | 139, 387, 5310 | bash, file, string | <h1>How to test if string exists in file with Bash?</h1>
<p>I have a file that contains directory names:</p>
<p><code>my_list.txt</code> :</p>
<pre><code>/tmp
/var/tmp
</code></pre>
<p>I'd like to check in Bash before I'll add a directory name if that name already exists in the file.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 179 | bash | # How to test if string exists in file with Bash?
I have a file that contains directory names:
`my_list.txt` :
```
/tmp
/var/tmp
```
I'd like to check in Bash before I'll add a directory name if that name already exists in the file. | ```
grep -Fxq "$FILENAME" my_list.txt
```
The exit status is 0 (true) if the name was found, 1 (false) if not, so:
```
if grep -Fxq "$FILENAME" my_list.txt
then
# code if found
else
# code if not found
fi
```
### Explanation
Here are the relevant sections of [the man page for `grep`](https://linux.die.net/m... |
9587445 | How to create a link to a directory on linux | 485 | 2012-03-06 16:08:40 | <p>How to create a link to an existing file or directory using a GNU Linux shell command?</p>
| 983,547 | 1,104,696 | 2024-01-16 23:39:18 | 9,587,490 | 867 | 2012-03-06 16:10:47 | 1,118,101 | 2024-01-16 23:39:18 | https://stackoverflow.com/q/9587445 | https://stackoverflow.com/a/9587490 | <p>Symbolic or soft link (files or directories, more flexible and self documenting)</p>
<pre><code># Source Link
ln -s /home/jake/doc/test/2000/something /home/jake/xxx
</code></pre>
<p>Hard link (files only, less flexible and not self documenting)</p>
<pre><code># Source ... | <p>Symbolic or soft link (files or directories, more flexible and self documenting)</p> <pre><code># Source Link ln -s /home/jake/doc/test/2000/something /home/jake/xxx </code></pre> <p>Hard link (files only, less flexible and not self documenting)</p> <pre><code># Source ... | 58, 390, 1796 | command, linux, shell | <h1>How to create a link to a directory on linux</h1>
<p>How to create a link to an existing file or directory using a GNU Linux shell command?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 180 | bash | # How to create a link to a directory on linux
How to create a link to an existing file or directory using a GNU Linux shell command? | Symbolic or soft link (files or directories, more flexible and self documenting)
```
# Source Link
ln -s /home/jake/doc/test/2000/something /home/jake/xxx
```
Hard link (files only, less flexible and not self documenting)
```
# Source Link
ln /home/jake/d... |
820517 | .bashrc at ssh login | 501 | 2009-05-04 15:10:11 | <p>When I ssh into my ubuntu-box running Hardy 8.04, the environment variables in my <code>.bashrc</code> are not set.</p>
<p>If I do a source <code>.bashrc</code>, the variables are properly set, and all is well.</p>
<p>How come <code>.bashrc</code> isn't run at login?</p>
| 216,083 | 339,046 | 2024-05-23 20:45:42 | 820,533 | 866 | 2009-05-04 15:14:39 | 40,005 | 2009-05-04 15:14:39 | https://stackoverflow.com/q/820517 | https://stackoverflow.com/a/820533 | <p><code>.bashrc</code> is not sourced when you log in using SSH. You need to source it in your <code>.bash_profile</code> like this:</p>
<pre><code>if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
</code></pre>
| <p><code>.bashrc</code> is not sourced when you log in using SSH. You need to source it in your <code>.bash_profile</code> like this:</p> <pre><code>if [ -f ~/.bashrc ]; then . ~/.bashrc fi </code></pre> | 386, 387, 549 | bash, ssh, ubuntu | <h1>.bashrc at ssh login</h1>
<p>When I ssh into my ubuntu-box running Hardy 8.04, the environment variables in my <code>.bashrc</code> are not set.</p>
<p>If I do a source <code>.bashrc</code>, the variables are properly set, and all is well.</p>
<p>How come <code>.bashrc</code> isn't run at login?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 181 | bash | # .bashrc at ssh login
When I ssh into my ubuntu-box running Hardy 8.04, the environment variables in my `.bashrc` are not set.
If I do a source `.bashrc`, the variables are properly set, and all is well.
How come `.bashrc` isn't run at login? | `.bashrc` is not sourced when you log in using SSH. You need to source it in your `.bash_profile` like this:
```
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
``` |
14219092 | Bash script – "/bin/bash^M: bad interpreter: No such file or directory" | 870 | 2013-01-08 16:03:35 | <p>I'm using <a href="http://linuxcommand.org/lc3_writing_shell_scripts.php" rel="noreferrer">this tutorial</a> to learn bash scripts to automate a few
tasks for me.<br />
I'm connecting to a server using putty.</p>
<p>The script, located in <code>.../Documents/LOG</code>, is:</p>
<pre><code>#!/bin/bash
# My first scri... | 1,379,886 | 350,668 | 2023-07-31 05:29:48 | 14,219,160 | 863 | 2013-01-08 16:07:24 | 992,151 | 2018-10-04 09:09:41 | https://stackoverflow.com/q/14219092 | https://stackoverflow.com/a/14219160 | <p>I have seen this issue when creating scripts in Windows env and then porting over to run on a Unix environment.</p>
<p>Try running <code>dos2unix</code> on the script:</p>
<p><a href="http://dos2unix.sourceforge.net/" rel="noreferrer">http://dos2unix.sourceforge.net/</a></p>
<p>Or just rewrite the script in your... | <p>I have seen this issue when creating scripts in Windows env and then porting over to run on a Unix environment.</p> <p>Try running <code>dos2unix</code> on the script:</p> <p><a href="http://dos2unix.sourceforge.net/" rel="noreferrer">http://dos2unix.sourceforge.net/</a></p> <p>Or just rewrite the script in your... | 387, 3705, 14899, 47852 | bash, carriage-return, linefeed, newline | <h1>Bash script – "/bin/bash^M: bad interpreter: No such file or directory"</h1>
<p>I'm using <a href="http://linuxcommand.org/lc3_writing_shell_scripts.php" rel="noreferrer">this tutorial</a> to learn bash scripts to automate a few
tasks for me.<br />
I'm connecting to a server using putty.</p>
<p>The script, located ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 182 | bash | # Bash script – "/bin/bash^M: bad interpreter: No such file or directory"
I'm using [this tutorial](http://linuxcommand.org/lc3_writing_shell_scripts.php) to learn bash scripts to automate a few
tasks for me.
I'm connecting to a server using putty.
The script, located in `.../Documents/LOG`, is:
```
#!/bin/bash
# ... | I have seen this issue when creating scripts in Windows env and then porting over to run on a Unix environment.
Try running `dos2unix` on the script:
<http://dos2unix.sourceforge.net/>
Or just rewrite the script in your Unix env using `vi` and test.
Unix uses different line endings so can't read the file you create... |
714877 | Setting Windows PowerShell environment variables | 1,071 | 2009-04-03 17:19:35 | <p>I have found out that setting the PATH environment variable affects only the old command prompt. PowerShell seems to have different environment settings. How do I change the environment variables for PowerShell (v1)?</p>
<p>Note:</p>
<p>I want to make my changes permanent, so I don't have to set it every time I run ... | 1,483,203 | 7,883 | 2025-07-08 10:20:30 | 714,918 | 854 | 2009-04-03 17:35:44 | 23,283 | 2023-04-16 20:35:27 | https://stackoverflow.com/q/714877 | https://stackoverflow.com/a/714918 | <p>Changing the actual environment variables can be done by
using the <code>env: namespace / drive</code> information. For example, this
code will update the path environment variable:</p>
<pre><code>$env:PATH = "SomeRandomPath"; (replaces existing path)
$env:PATH += ";SomeRandomPath" ... | <p>Changing the actual environment variables can be done by using the <code>env: namespace / drive</code> information. For example, this code will update the path environment variable:</p> <pre><code>$env:PATH = "SomeRandomPath"; (replaces existing path) $env:PATH += ";SomeRandomPath" ... | 64, 526 | powershell, windows | <h1>Setting Windows PowerShell environment variables</h1>
<p>I have found out that setting the PATH environment variable affects only the old command prompt. PowerShell seems to have different environment settings. How do I change the environment variables for PowerShell (v1)?</p>
<p>Note:</p>
<p>I want to make my chan... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 183 | bash | # Setting Windows PowerShell environment variables
I have found out that setting the PATH environment variable affects only the old command prompt. PowerShell seems to have different environment settings. How do I change the environment variables for PowerShell (v1)?
Note:
I want to make my changes permanent, so I d... | Changing the actual environment variables can be done by
using the `env: namespace / drive` information. For example, this
code will update the path environment variable:
```
$env:PATH = "SomeRandomPath"; (replaces existing path)
$env:PATH += ";SomeRandomPath" (appends to existing path)
```
##... |
6270440 | How to test string and integer equality, and combine with logical && and || operators in bash? | 339 | 2011-06-07 19:18:05 | <p>I have a couple of variables and I want to check the following condition (written out in words, then my failed attempt at bash scripting):</p>
<pre><code>if varA EQUALS 1 AND ( varB EQUALS "t1" OR varB EQUALS "t2" ) then
do something
done.
</code></pre>
<p>And in my failed attempt, I came up with:</p>
<pre><co... | 425,352 | 381,798 | 2024-01-05 08:26:42 | 6,270,803 | 854 | 2011-06-07 19:49:29 | 387,076 | 2023-12-19 10:23:24 | https://stackoverflow.com/q/6270440 | https://stackoverflow.com/a/6270803 | <p>What you've written actually almost works (it would work if all the variables were numbers), but it's not an idiomatic way at all.</p>
<ul>
<li><code>(…)</code> parentheses indicate a <a href="http://www.gnu.org/software/bash/manual/bash.html#Command-Grouping" rel="noreferrer">subshell</a>. What's inside them isn't ... | <p>What you've written actually almost works (it would work if all the variables were numbers), but it's not an idiomatic way at all.</p> <ul> <li><code>(…)</code> parentheses indicate a <a href="http://www.gnu.org/software/bash/manual/bash.html#Command-Grouping" rel="noreferrer">subshell</a>. What's inside them isn't ... | 387, 27114 | bash, logical-operators | <h1>How to test string and integer equality, and combine with logical && and || operators in bash?</h1>
<p>I have a couple of variables and I want to check the following condition (written out in words, then my failed attempt at bash scripting):</p>
<pre><code>if varA EQUALS 1 AND ( varB EQUALS "t1" OR varB EQUALS "t2... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 184 | bash | # How to test string and integer equality, and combine with logical && and || operators in bash?
I have a couple of variables and I want to check the following condition (written out in words, then my failed attempt at bash scripting):
```
if varA EQUALS 1 AND ( varB EQUALS "t1" OR varB EQUALS "t2" ) then
do someth... | What you've written actually almost works (it would work if all the variables were numbers), but it's not an idiomatic way at all.
- `(…)` parentheses indicate a [subshell](http://www.gnu.org/software/bash/manual/bash.html#Command-Grouping). What's inside them isn't an expression like in many other languages. It's a l... |
1752677 | How can I recursively delete an entire directory with PowerShell 2.0? | 498 | 2009-11-17 23:43:39 | <p>What is the simplest way to forcefully delete a directory and all its subdirectories in PowerShell? I am using PowerShell V2 in Windows 7.</p>
<p>I have learned from several sources that the most obvious command, <code>Remove-Item $targetDir -Recurse -Force</code>, does not work correctly. This includes a statement ... | 721,892 | 58,525 | 2025-07-17 21:39:42 | 1,752,751 | 852 | 2009-11-18 00:03:17 | 73,070 | 2025-07-17 18:10:28 | https://stackoverflow.com/q/1752677 | https://stackoverflow.com/a/1752751 | <pre class="lang-none prettyprint-override"><code>Remove-Item -Recurse -Force some_directory
</code></pre>
<p>does indeed work as advertised here.</p>
<pre class="lang-none prettyprint-override"><code>rm -r -fo some_directory
</code></pre>
<p>are shorthand aliases that work too.</p>
<p>As far as I understood it, the <c... | <pre class="lang-none prettyprint-override"><code>Remove-Item -Recurse -Force some_directory </code></pre> <p>does indeed work as advertised here.</p> <pre class="lang-none prettyprint-override"><code>rm -r -fo some_directory </code></pre> <p>are shorthand aliases that work too.</p> <p>As far as I understood it, the <c... | 64, 99, 526, 34595, 106270 | delete-directory, filesystems, powershell, windows, windows-7 | <h1>How can I recursively delete an entire directory with PowerShell 2.0?</h1>
<p>What is the simplest way to forcefully delete a directory and all its subdirectories in PowerShell? I am using PowerShell V2 in Windows 7.</p>
<p>I have learned from several sources that the most obvious command, <code>Remove-Item $target... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 185 | bash | # How can I recursively delete an entire directory with PowerShell 2.0?
What is the simplest way to forcefully delete a directory and all its subdirectories in PowerShell? I am using PowerShell V2 in Windows 7.
I have learned from several sources that the most obvious command, `Remove-Item $targetDir -Recurse -Force`... | ```
Remove-Item -Recurse -Force some_directory
```
does indeed work as advertised here.
```
rm -r -fo some_directory
```
are shorthand aliases that work too.
As far as I understood it, the `-Recurse` parameter just doesn't work correctly when you try deleting a filtered set of files recursively. For killing a singl... |
4774054 | Reliable way for a Bash script to get the full path to itself | 974 | 2011-01-23 13:24:16 | <p>I have a Bash script that needs to know its full path. I'm trying to find a broadly-compatible way of doing that without ending up with relative or funky-looking paths. I only need to support Bash, not sh, csh, etc.</p>
<p>What I've found so far:</p>
<ol>
<li><p>The accepted answer to <em><a href="https://stackove... | 758,568 | 157,247 | 2022-06-24 11:18:11 | 4,774,063 | 839 | 2011-01-23 13:25:57 | 157,247 | 2021-03-03 15:47:11 | https://stackoverflow.com/q/4774054 | https://stackoverflow.com/a/4774063 | <p>Here's what I've come up with (edit: plus some tweaks provided by <a href="https://stackoverflow.com/users/1430833/sfstewman">sfstewman</a>, <a href="https://stackoverflow.com/users/397210/levigroker">levigroker</a>, <a href="https://stackoverflow.com/users/1858225/kyle-strand">Kyle Strand</a>, and <a href="https://... | <p>Here's what I've come up with (edit: plus some tweaks provided by <a href="https://stackoverflow.com/users/1430833/sfstewman">sfstewman</a>, <a href="https://stackoverflow.com/users/397210/levigroker">levigroker</a>, <a href="https://stackoverflow.com/users/1858225/kyle-strand">Kyle Strand</a>, and <a href="https://... | 387, 6268 | bash, path | <h1>Reliable way for a Bash script to get the full path to itself</h1>
<p>I have a Bash script that needs to know its full path. I'm trying to find a broadly-compatible way of doing that without ending up with relative or funky-looking paths. I only need to support Bash, not sh, csh, etc.</p>
<p>What I've found so far... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 186 | bash | # Reliable way for a Bash script to get the full path to itself
I have a Bash script that needs to know its full path. I'm trying to find a broadly-compatible way of doing that without ending up with relative or funky-looking paths. I only need to support Bash, not sh, csh, etc.
What I've found so far:
1. The accept... | Here's what I've come up with (edit: plus some tweaks provided by [sfstewman](https://stackoverflow.com/users/1430833/sfstewman), [levigroker](https://stackoverflow.com/users/397210/levigroker), [Kyle Strand](https://stackoverflow.com/users/1858225/kyle-strand), and [Rob Kennedy](https://stackoverflow.com/users/33732/r... |
3737740 | Is there a better way to run a command N times in bash? | 534 | 2010-09-17 17:56:25 | <p>I occasionally run a bash command line like this:</p>
<pre><code>n=0; while [[ $n -lt 10 ]]; do some_command; n=$((n+1)); done
</code></pre>
<p>To run <code>some_command</code> a number of times in a row -- 10 times in this case.</p>
<p>Often <code>some_command</code> is really a chain of commands or a pipeline.<... | 421,977 | 67,022 | 2024-02-29 01:41:06 | 3,737,773 | 837 | 2010-09-17 18:01:50 | 76,310 | 2021-07-14 23:20:38 | https://stackoverflow.com/q/3737740 | https://stackoverflow.com/a/3737773 | <p>If your range has a variable, <a href="//unix.stackexchange.com/a/460600/17671">use <code>seq</code></a>, like this:</p>
<pre><code>count=10
for i in $(seq $count); do
command
done
</code></pre>
<p>Simply:</p>
<pre><code>for run in {1..10}; do
command
done
</code></pre>
<p>Or as a one-liner, for those that wan... | <p>If your range has a variable, <a href="//unix.stackexchange.com/a/460600/17671">use <code>seq</code></a>, like this:</p> <pre><code>count=10 for i in $(seq $count); do command done </code></pre> <p>Simply:</p> <pre><code>for run in {1..10}; do command done </code></pre> <p>Or as a one-liner, for those that wan... | 387, 2314 | bash, loops | <h1>Is there a better way to run a command N times in bash?</h1>
<p>I occasionally run a bash command line like this:</p>
<pre><code>n=0; while [[ $n -lt 10 ]]; do some_command; n=$((n+1)); done
</code></pre>
<p>To run <code>some_command</code> a number of times in a row -- 10 times in this case.</p>
<p>Often <code>... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 187 | bash | # Is there a better way to run a command N times in bash?
I occasionally run a bash command line like this:
```
n=0; while [[ $n -lt 10 ]]; do some_command; n=$((n+1)); done
```
To run `some_command` a number of times in a row -- 10 times in this case.
Often `some_command` is really a chain of commands or a pipelin... | If your range has a variable, [use `seq`](//unix.stackexchange.com/a/460600/17671), like this:
```
count=10
for i in $(seq $count); do
command
done
```
Simply:
```
for run in {1..10}; do
command
done
```
Or as a one-liner, for those that want to copy and paste easily:
```
for run in {1..10}; do command; done... |
1908610 | How to get process ID of background process? | 559 | 2009-12-15 16:24:00 | <p>I start a background process from my shell script, and I would like to kill this process when my script finishes.</p>
<p>How to get the PID of this process from my shell script? As far as I can see variable <code>$!</code> contains the PID of the current script, not the background process.</p>
| 426,345 | 167,739 | 2024-07-02 14:19:03 | 1,911,387 | 834 | 2009-12-16 00:05:40 | 23,744 | 2009-12-16 00:05:40 | https://stackoverflow.com/q/1908610 | https://stackoverflow.com/a/1911387 | <p>You need to save the PID of the background process at the time you start it:</p>
<pre><code>foo &
FOO_PID=$!
# do other stuff
kill $FOO_PID
</code></pre>
<p>You cannot use job control, since that is an interactive feature and tied to a controlling terminal. A script will not necessarily have a terminal attache... | <p>You need to save the PID of the background process at the time you start it:</p> <pre><code>foo & FOO_PID=$! # do other stuff kill $FOO_PID </code></pre> <p>You cannot use job control, since that is an interactive feature and tied to a controlling terminal. A script will not necessarily have a terminal attache... | 58, 390, 3300, 15292 | background-process, linux, pid, shell | <h1>How to get process ID of background process?</h1>
<p>I start a background process from my shell script, and I would like to kill this process when my script finishes.</p>
<p>How to get the PID of this process from my shell script? As far as I can see variable <code>$!</code> contains the PID of the current script,... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 188 | bash | # How to get process ID of background process?
I start a background process from my shell script, and I would like to kill this process when my script finishes.
How to get the PID of this process from my shell script? As far as I can see variable `$!` contains the PID of the current script, not the background process... | You need to save the PID of the background process at the time you start it:
```
foo &
FOO_PID=$!
# do other stuff
kill $FOO_PID
```
You cannot use job control, since that is an interactive feature and tied to a controlling terminal. A script will not necessarily have a terminal attached at all so job control will no... |
192319 | How do I know the script file name in a Bash script? | 802 | 2008-10-10 17:20:41 | <p>How can I determine the name of the Bash script file inside the script itself?</p>
<p>Like if my script is in file <code>runme.sh</code>, then how would I make it to display "You are running runme.sh" message without hardcoding that?</p>
| 688,434 | 20,390 | 2023-07-13 08:00:03 | 192,337 | 833 | 2008-10-10 17:23:08 | 23,512 | 2023-07-12 20:02:57 | https://stackoverflow.com/q/192319 | https://stackoverflow.com/a/192337 | <pre class="lang-bash prettyprint-override"><code>me=$(basename "$0")
</code></pre>
<p>For reading through a symlink<sup>1</sup>, which is usually not what you want (you usually don't want to confuse the user this way), try:</p>
<pre class="lang-bash prettyprint-override"><code>me="$(basename "$(tes... | <pre class="lang-bash prettyprint-override"><code>me=$(basename "$0") </code></pre> <p>For reading through a symlink<sup>1</sup>, which is usually not what you want (you usually don't want to confuse the user this way), try:</p> <pre class="lang-bash prettyprint-override"><code>me="$(basename "$(tes... | 58, 387, 390, 531 | bash, linux, scripting, shell | <h1>How do I know the script file name in a Bash script?</h1>
<p>How can I determine the name of the Bash script file inside the script itself?</p>
<p>Like if my script is in file <code>runme.sh</code>, then how would I make it to display "You are running runme.sh" message without hardcoding that?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 189 | bash | # How do I know the script file name in a Bash script?
How can I determine the name of the Bash script file inside the script itself?
Like if my script is in file `runme.sh`, then how would I make it to display "You are running runme.sh" message without hardcoding that? | ```
me=$(basename "$0")
```
For reading through a symlink1, which is usually not what you want (you usually don't want to confuse the user this way), try:
```
me="$(basename "$(test -L "$0" && readlink "$0" || echo "$0")")"
```
IMO, that'll produce confusing output. "I ran foo.sh, but it's saying I'm running bar.sh!... |
3474526 | Stop on first error | 479 | 2010-08-13 06:45:49 | <blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="https://stackoverflow.com/questions/2870992/automatic-exit-from-bash-shell-script-on-error">Automatic exit from bash shell script on error</a> </p>
</blockquote>
<p>How can I have bash stop on the first command failure, without putting stuff like... | 356,651 | 149,482 | 2019-02-02 11:30:14 | 3,474,556 | 833 | 2010-08-13 06:50:49 | 226,621 | 2019-02-02 11:30:14 | https://stackoverflow.com/q/3474526 | https://stackoverflow.com/a/3474556 | <p>Maybe you want <code>set -e</code>:</p>
<p><a href="http://web.archive.org/web/20110314180918/http://www.davidpashley.com/articles/writing-robust-shell-scripts.html" rel="noreferrer">www.davidpashley.com/articles/writing-robust-shell-scripts.html#id2382181</a>:</p>
<blockquote>
<p>This tells bash that it should ... | <p>Maybe you want <code>set -e</code>:</p> <p><a href="http://web.archive.org/web/20110314180918/http://www.davidpashley.com/articles/writing-robust-shell-scripts.html" rel="noreferrer">www.davidpashley.com/articles/writing-robust-shell-scripts.html#id2382181</a>:</p> <blockquote> <p>This tells bash that it should ... | 387 | bash | <h1>Stop on first error</h1>
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="https://stackoverflow.com/questions/2870992/automatic-exit-from-bash-shell-script-on-error">Automatic exit from bash shell script on error</a> </p>
</blockquote>
<p>How can I have bash stop on the first command failur... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 190 | bash | # Stop on first error
> **Possible Duplicate:**
> [Automatic exit from bash shell script on error](https://stackoverflow.com/questions/2870992/automatic-exit-from-bash-shell-script-on-error)
How can I have bash stop on the first command failure, without putting stuff like this all through my code?
```
some_prog ||... | Maybe you want `set -e`:
[www.davidpashley.com/articles/writing-robust-shell-scripts.html#id2382181](http://web.archive.org/web/20110314180918/http://www.davidpashley.com/articles/writing-robust-shell-scripts.html):
> This tells bash that it should exit the script if any statement returns a non-true return value. The... |
19456518 | Error when using 'sed' with 'find' command on OS X: "invalid command code ." | 360 | 2013-10-18 18:22:21 | <p>Being forced to use CVS for a current client and the address changed for the remote repo. The only way I can find to change the remote address in my local code is a recursive search and replace.</p>
<p>However, with the sed command I'd expect to work:</p>
<pre><code>find ./ -type f -exec sed -i "s/192.168.20.1/new... | 232,272 | 143,269 | 2024-11-03 16:20:04 | 19,457,213 | 831 | 2013-10-18 19:02:18 | 1,763,614 | 2016-01-20 22:57:42 | https://stackoverflow.com/q/19456518 | https://stackoverflow.com/a/19457213 | <p>If you are on a OS X, this probably has nothing to do with the sed command. On the OSX version of <code>sed</code>, the <code>-i</code> option expects an <code>extension</code> argument so your command is actually parsed as the <code>extension</code> argument and the file path is interpreted as the command code.</p>... | <p>If you are on a OS X, this probably has nothing to do with the sed command. On the OSX version of <code>sed</code>, the <code>-i</code> option expects an <code>extension</code> argument so your command is actually parsed as the <code>extension</code> argument and the file path is interpreted as the command code.</p>... | 369, 387, 5282, 10193 | bash, find, macos, sed | <h1>Error when using 'sed' with 'find' command on OS X: "invalid command code ."</h1>
<p>Being forced to use CVS for a current client and the address changed for the remote repo. The only way I can find to change the remote address in my local code is a recursive search and replace.</p>
<p>However, with the sed comman... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 191 | bash | # Error when using 'sed' with 'find' command on OS X: "invalid command code ."
Being forced to use CVS for a current client and the address changed for the remote repo. The only way I can find to change the remote address in my local code is a recursive search and replace.
However, with the sed command I'd expect to ... | If you are on a OS X, this probably has nothing to do with the sed command. On the OSX version of `sed`, the `-i` option expects an `extension` argument so your command is actually parsed as the `extension` argument and the file path is interpreted as the command code.
Try adding the `-e` argument explicitly and givin... |
5592531 | How can I pass an argument to a PowerShell script? | 621 | 2011-04-08 08:33:33 | <p>There's a PowerShell script named <code>itunesForward.ps1</code> that makes iTunes fast forward 30 seconds:</p>
<pre><code>$iTunes = New-Object -ComObject iTunes.Application
if ($iTunes.playerstate -eq 1)
{
$iTunes.PlayerPosition = $iTunes.PlayerPosition + 30
}
</code></pre>
<p>It is executed with a prompt line c... | 1,051,878 | 32,090 | 2025-04-14 17:30:47 | 5,592,684 | 827 | 2011-04-08 08:48:54 | 307,138 | 2022-08-09 19:49:54 | https://stackoverflow.com/q/5592531 | https://stackoverflow.com/a/5592684 | <p>Tested as working:</p>
<pre><code>#Must be the first statement in your script (not counting comments)
param([Int32]$step=30)
$iTunes = New-Object -ComObject iTunes.Application
if ($iTunes.playerstate -eq 1)
{
$iTunes.PlayerPosition = $iTunes.PlayerPosition + $step
}
</code></pre>
<p>Call it with</p>
<pre><code>... | <p>Tested as working:</p> <pre><code>#Must be the first statement in your script (not counting comments) param([Int32]$step=30) $iTunes = New-Object -ComObject iTunes.Application if ($iTunes.playerstate -eq 1) { $iTunes.PlayerPosition = $iTunes.PlayerPosition + $step } </code></pre> <p>Call it with</p> <pre><code>... | 526, 1231, 1362, 4323, 10355 | automation, command-line, itunes, parameter-passing, powershell | <h1>How can I pass an argument to a PowerShell script?</h1>
<p>There's a PowerShell script named <code>itunesForward.ps1</code> that makes iTunes fast forward 30 seconds:</p>
<pre><code>$iTunes = New-Object -ComObject iTunes.Application
if ($iTunes.playerstate -eq 1)
{
$iTunes.PlayerPosition = $iTunes.PlayerPosition... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 192 | bash | # How can I pass an argument to a PowerShell script?
There's a PowerShell script named `itunesForward.ps1` that makes iTunes fast forward 30 seconds:
```
$iTunes = New-Object -ComObject iTunes.Application
if ($iTunes.playerstate -eq 1)
{
$iTunes.PlayerPosition = $iTunes.PlayerPosition + 30
}
```
It is executed wi... | Tested as working:
```
#Must be the first statement in your script (not counting comments)
param([Int32]$step=30)
$iTunes = New-Object -ComObject iTunes.Application
if ($iTunes.playerstate -eq 1)
{
$iTunes.PlayerPosition = $iTunes.PlayerPosition + $step
}
```
Call it with
```
powershell.exe -file itunesForward.... |
19306771 | How do I get the current user's username in Bash? | 582 | 2013-10-10 21:43:58 | <p>How do I get the current user's username in Bash? Do I use <a href="https://linux.die.net/man/1/whoami" rel="noreferrer"><code>whoami</code></a>?</p>
| 829,509 | 2,868,901 | 2025-01-25 22:37:14 | 19,306,837 | 825 | 2013-10-10 21:49:00 | 1,399,279 | 2022-05-31 03:47:33 | https://stackoverflow.com/q/19306771 | https://stackoverflow.com/a/19306837 | <p>On the command line, enter</p>
<pre><code>whoami
</code></pre>
<p>or</p>
<pre><code>echo "$USER"
</code></pre>
| <p>On the command line, enter</p> <pre><code>whoami </code></pre> <p>or</p> <pre><code>echo "$USER" </code></pre> | 387 | bash | <h1>How do I get the current user's username in Bash?</h1>
<p>How do I get the current user's username in Bash? Do I use <a href="https://linux.die.net/man/1/whoami" rel="noreferrer"><code>whoami</code></a>?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 193 | bash | # How do I get the current user's username in Bash?
How do I get the current user's username in Bash? Do I use [`whoami`](https://linux.die.net/man/1/whoami)? | On the command line, enter
```
whoami
```
or
```
echo "$USER"
``` |
9392735 | Linux how to copy but not overwrite? | 541 | 2012-02-22 10:09:35 | <p>I want to <code>cp</code> a directory but I do not want to overwrite any existing files even it they are older than the copied files. And I want to do it completely noninteractive as this will be a part of a Crontab Bash script. Any ideas?</p>
| 548,027 | 940,208 | 2020-08-27 04:24:29 | 9,392,784 | 824 | 2012-02-22 10:12:11 | 1,007,273 | 2016-05-26 18:56:30 | https://stackoverflow.com/q/9392735 | https://stackoverflow.com/a/9392784 | <p>Taken from the <a href="http://manpages.ubuntu.com/manpages/precise/en/man1/cp.1.html" rel="noreferrer">man page</a>:</p>
<pre><code>-n, --no-clobber
do not overwrite an existing file (overrides a previous -i option)
</code></pre>
<p>Example:</p>
<pre><code>cp -n myoldfile.txt mycopiedfile.txt
</cod... | <p>Taken from the <a href="http://manpages.ubuntu.com/manpages/precise/en/man1/cp.1.html" rel="noreferrer">man page</a>:</p> <pre><code>-n, --no-clobber do not overwrite an existing file (overrides a previous -i option) </code></pre> <p>Example:</p> <pre><code>cp -n myoldfile.txt mycopiedfile.txt </cod... | 58, 387, 25299 | bash, cp, linux | <h1>Linux how to copy but not overwrite?</h1>
<p>I want to <code>cp</code> a directory but I do not want to overwrite any existing files even it they are older than the copied files. And I want to do it completely noninteractive as this will be a part of a Crontab Bash script. Any ideas?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 194 | bash | # Linux how to copy but not overwrite?
I want to `cp` a directory but I do not want to overwrite any existing files even it they are older than the copied files. And I want to do it completely noninteractive as this will be a part of a Crontab Bash script. Any ideas? | Taken from the [man page](http://manpages.ubuntu.com/manpages/precise/en/man1/cp.1.html):
```
-n, --no-clobber
do not overwrite an existing file (overrides a previous -i option)
```
Example:
```
cp -n myoldfile.txt mycopiedfile.txt
``` |
13617843 | "unary operator expected" error in Bash if condition | 384 | 2012-11-29 02:22:47 | <p>This script is getting an error:</p>
<pre><code>elif [ $operation = "man" ]; then
if [ $aug1 = "add" ]; then # <- Line 75
echo "Man Page for: add"
echo ""
echo "Syntax: add [number 1] [number 2]"
echo ""
echo "Descrip... | 661,528 | 1,832,837 | 2022-07-05 23:33:57 | 13,618,376 | 821 | 2012-11-29 03:31:22 | 1,566,221 | 2021-10-05 14:08:41 | https://stackoverflow.com/q/13617843 | https://stackoverflow.com/a/13618376 | <p>If you know you're always going to use Bash, it's much easier to always use the double bracket conditional compound command <code>[[ ... ]]</code>, instead of the POSIX-compatible single bracket version <code>[ ... ]</code>. Inside a <code>[[ ... ]]</code> compound, word-splitting and pathname expansion are not appl... | <p>If you know you're always going to use Bash, it's much easier to always use the double bracket conditional compound command <code>[[ ... ]]</code>, instead of the POSIX-compatible single bracket version <code>[ ... ]</code>. Inside a <code>[[ ... ]]</code> compound, word-splitting and pathname expansion are not appl... | 387, 390 | bash, shell | <h1>"unary operator expected" error in Bash if condition</h1>
<p>This script is getting an error:</p>
<pre><code>elif [ $operation = "man" ]; then
if [ $aug1 = "add" ]; then # <- Line 75
echo "Man Page for: add"
echo ""
echo "Syntax: add [number 1]... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 195 | bash | # "unary operator expected" error in Bash if condition
This script is getting an error:
```
elif [ $operation = "man" ]; then
if [ $aug1 = "add" ]; then # <- Line 75
echo "Man Page for: add"
echo ""
echo "Syntax: add [number 1] [number 2]"
echo ""
echo "Description:"
echo "Add two ... | If you know you're always going to use Bash, it's much easier to always use the double bracket conditional compound command `[[ ... ]]`, instead of the POSIX-compatible single bracket version `[ ... ]`. Inside a `[[ ... ]]` compound, word-splitting and pathname expansion are not applied to words, so you can rely on
``... |
2150614 | Concatenating multiple text files into a single file in Bash | 472 | 2010-01-27 22:03:28 | <p>What is the quickest and most pragmatic way to combine all *.txt file in a directory into one large text file?</p>
<p>Currently I'm using windows with cygwin so I have access to BASH.</p>
<p>Windows shell command would be nice too but I doubt there is one.</p>
| 496,244 | 45,066 | 2021-11-13 11:25:52 | 2,150,625 | 818 | 2010-01-27 22:04:44 | 110,088 | 2010-01-27 23:35:06 | https://stackoverflow.com/q/2150614 | https://stackoverflow.com/a/2150625 | <p>This appends the output to all.txt</p>
<pre><code>cat *.txt >> all.txt
</code></pre>
<p>This overwrites all.txt</p>
<pre><code>cat *.txt > all.txt
</code></pre>
| <p>This appends the output to all.txt</p> <pre><code>cat *.txt >> all.txt </code></pre> <p>This overwrites all.txt</p> <pre><code>cat *.txt > all.txt </code></pre> | 387, 390 | bash, shell | <h1>Concatenating multiple text files into a single file in Bash</h1>
<p>What is the quickest and most pragmatic way to combine all *.txt file in a directory into one large text file?</p>
<p>Currently I'm using windows with cygwin so I have access to BASH.</p>
<p>Windows shell command would be nice too but I doubt th... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 196 | bash | # Concatenating multiple text files into a single file in Bash
What is the quickest and most pragmatic way to combine all *.txt file in a directory into one large text file?
Currently I'm using windows with cygwin so I have access to BASH.
Windows shell command would be nice too but I doubt there is one. | This appends the output to all.txt
```
cat *.txt >> all.txt
```
This overwrites all.txt
```
cat *.txt > all.txt
``` |
3953645 | Ternary operator (?:) in Bash | 807 | 2010-10-17 14:38:52 | <p>Is there a way to do something like this</p>
<pre><code>int a = (b == 5) ? c : d;
</code></pre>
<p>using Bash?</p>
| 501,290 | 201,065 | 2025-12-21 10:30:25 | 3,953,666 | 817 | 2010-10-17 14:42:42 | 131,527 | 2025-01-03 02:56:45 | https://stackoverflow.com/q/3953645 | https://stackoverflow.com/a/3953666 | <p>The ternary operator <code>? :</code> is just a short form of <code>if/then/else</code>:</p>
<pre><code>case "$b" in
5) a=$c ;;
*) a=$d ;;
esac
</code></pre>
<p>Or:</p>
<pre><code>[[ $b = 5 ]] && a="$c" || a="$d"
</code></pre>
| <p>The ternary operator <code>? :</code> is just a short form of <code>if/then/else</code>:</p> <pre><code>case "$b" in 5) a=$c ;; *) a=$d ;; esac </code></pre> <p>Or:</p> <pre><code>[[ $b = 5 ]] && a="$c" || a="$d" </code></pre> | 367, 387, 15904 | bash, conditional-operator, syntax | <h1>Ternary operator (?:) in Bash</h1>
<p>Is there a way to do something like this</p>
<pre><code>int a = (b == 5) ? c : d;
</code></pre>
<p>using Bash?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 197 | bash | # Ternary operator (?:) in Bash
Is there a way to do something like this
```
int a = (b == 5) ? c : d;
```
using Bash? | The ternary operator `? :` is just a short form of `if/then/else`:
```
case "$b" in
5) a=$c ;;
*) a=$d ;;
esac
```
Or:
```
[[ $b = 5 ]] && a="$c" || a="$d"
``` |
6481005 | How to obtain the number of CPUs/cores in Linux from the command line? | 731 | 2011-06-25 22:52:34 | <p>I have this script, but I do not know how to get the last element in the printout:</p>
<pre><code>cat /proc/cpuinfo | awk '/^processor/{print $3}'
</code></pre>
<p>The last element should be the number of CPUs, minus 1.</p>
| 855,982 | 486,720 | 2024-10-26 12:30:58 | 6,481,016 | 814 | 2011-06-25 22:56:01 | 349,909 | 2021-05-23 14:05:25 | https://stackoverflow.com/q/6481005 | https://stackoverflow.com/a/6481016 | <pre><code>grep -c ^processor /proc/cpuinfo
</code></pre>
<p>will count the number of lines starting with "processor" in <code>/proc/cpuinfo</code></p>
<p>For systems with hyper-threading, you can use</p>
<pre><code>grep ^cpu\\scores /proc/cpuinfo | uniq | awk '{print $4}'
</code></pre>
<p>which should retur... | <pre><code>grep -c ^processor /proc/cpuinfo </code></pre> <p>will count the number of lines starting with "processor" in <code>/proc/cpuinfo</code></p> <p>For systems with hyper-threading, you can use</p> <pre><code>grep ^cpu\\scores /proc/cpuinfo | uniq | awk '{print $4}' </code></pre> <p>which should retur... | 58, 387, 448, 23364 | bash, cpu, cpu-cores, linux | <h1>How to obtain the number of CPUs/cores in Linux from the command line?</h1>
<p>I have this script, but I do not know how to get the last element in the printout:</p>
<pre><code>cat /proc/cpuinfo | awk '/^processor/{print $3}'
</code></pre>
<p>The last element should be the number of CPUs, minus 1.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 198 | bash | # How to obtain the number of CPUs/cores in Linux from the command line?
I have this script, but I do not know how to get the last element in the printout:
```
cat /proc/cpuinfo | awk '/^processor/{print $3}'
```
The last element should be the number of CPUs, minus 1. | ```
grep -c ^processor /proc/cpuinfo
```
will count the number of lines starting with "processor" in `/proc/cpuinfo`
For systems with hyper-threading, you can use
```
grep ^cpu\\scores /proc/cpuinfo | uniq | awk '{print $4}'
```
which should return (for example) `8` (whereas the command above would return `16`) |
1527049 | How can I join elements of a Bash array into a delimited string? | 628 | 2009-10-06 17:46:15 | <p>If I have an array like this in Bash:</p>
<pre><code>FOO=( a b c )
</code></pre>
<p>How do I join the elements with commas? For example, producing <code>a,b,c</code>.</p>
| 417,408 | 71,522 | 2024-07-02 11:41:26 | 17,841,619 | 814 | 2013-07-24 18:07:43 | 789,544 | 2022-01-14 21:51:08 | https://stackoverflow.com/q/1527049 | https://stackoverflow.com/a/17841619 | <p>A 100% pure Bash function that supports multi-character delimiters is:</p>
<pre><code>function join_by {
local d=${1-} f=${2-}
if shift 2; then
printf %s "$f" "${@/#/$d}"
fi
}
</code></pre>
<p>For example,</p>
<pre><code>join_by , a b c #a,b,c
join_by ' , ' a b c #a , b , c
join_by ')|(... | <p>A 100% pure Bash function that supports multi-character delimiters is:</p> <pre><code>function join_by { local d=${1-} f=${2-} if shift 2; then printf %s "$f" "${@/#/$d}" fi } </code></pre> <p>For example,</p> <pre><code>join_by , a b c #a,b,c join_by ' , ' a b c #a , b , c join_by ')|(... | 114, 387 | arrays, bash | <h1>How can I join elements of a Bash array into a delimited string?</h1>
<p>If I have an array like this in Bash:</p>
<pre><code>FOO=( a b c )
</code></pre>
<p>How do I join the elements with commas? For example, producing <code>a,b,c</code>.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 199 | bash | # How can I join elements of a Bash array into a delimited string?
If I have an array like this in Bash:
```
FOO=( a b c )
```
How do I join the elements with commas? For example, producing `a,b,c`. | A 100% pure Bash function that supports multi-character delimiters is:
```
function join_by {
local d=${1-} f=${2-}
if shift 2; then
printf %s "$f" "${@/#/$d}"
fi
}
```
For example,
```
join_by , a b c #a,b,c
join_by ' , ' a b c #a , b , c
join_by ')|(' a b c #a)|(b)|(c
join_by ' %s ' a b c #a %s b %s c
jo... |
3202111 | How can I assign a name for a screen? | 536 | 2010-07-08 09:15:44 | <p>I'm using the <a href="https://en.wikipedia.org/wiki/GNU_Screen" rel="noreferrer">Screen</a> multiplexer tool on the command shell and open a lot of screens. I then forget which process ID associates with which task.</p>
<p>I would like to set a name for a screen, but I can't find an option in the <a href="https://e... | 444,154 | 131,664 | 2024-09-16 05:34:19 | 3,309,696 | 812 | 2010-07-22 14:05:36 | 164,176 | 2024-09-16 05:34:19 | https://stackoverflow.com/q/3202111 | https://stackoverflow.com/a/3309696 | <h1>To start a new session</h1>
<p><code>screen -S your_session_name</code></p>
<h1>To rename an existing session</h1>
<p><kbd>Ctrl</kbd>+<kbd>a</kbd>, <kbd>:</kbd> <code>sessionname</code> $YOUR_SESSION_NAME <kbd>Enter</kbd></p>
<blockquote>
<p>You must be inside the session</p>
</blockquote>
<blockquote>
<p><code>ses... | <h1>To start a new session</h1> <p><code>screen -S your_session_name</code></p> <h1>To rename an existing session</h1> <p><kbd>Ctrl</kbd>+<kbd>a</kbd>, <kbd>:</kbd> <code>sessionname</code> $YOUR_SESSION_NAME <kbd>Enter</kbd></p> <blockquote> <p>You must be inside the session</p> </blockquote> <blockquote> <p><code>ses... | 34, 58, 390, 5024 | gnu-screen, linux, shell, unix | <h1>How can I assign a name for a screen?</h1>
<p>I'm using the <a href="https://en.wikipedia.org/wiki/GNU_Screen" rel="noreferrer">Screen</a> multiplexer tool on the command shell and open a lot of screens. I then forget which process ID associates with which task.</p>
<p>I would like to set a name for a screen, but I... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 200 | bash | # How can I assign a name for a screen?
I'm using the [Screen](https://en.wikipedia.org/wiki/GNU_Screen) multiplexer tool on the command shell and open a lot of screens. I then forget which process ID associates with which task.
I would like to set a name for a screen, but I can't find an option in the [man page](htt... | # To start a new session
`screen -S your_session_name`
# To rename an existing session
`Ctrl`+`a`, `:` `sessionname` $YOUR_SESSION_NAME `Enter`
> You must be inside the session
> `sessionname` is command, please type it exactly, not your session name there - yours will be at $YOUR_SESSION_NAME |
1550288 | OS X Terminal Colors | 544 | 2009-10-11 09:43:01 | <p>I just got a Mac after working with Ubuntu Linux for some time. Among the many things I'm trying to figure out is the absence of colors in my terminal window- like the ones that are shown (on Linux) when running <code>ls -la</code> or <code>git status</code>.</p>
<p>How can one activate colors in their shell?</p>
| 526,736 | 187,907 | 2024-03-15 01:25:39 | 5,485,184 | 810 | 2011-03-30 10:35:21 | 411,951 | 2019-11-20 19:06:03 | https://stackoverflow.com/q/1550288 | https://stackoverflow.com/a/5485184 | <p>Here is a solution I've found to enable the global
<a href="http://it.toolbox.com/blogs/lim/how-to-fix-colors-on-mac-osx-terminal-37214" rel="noreferrer">terminal colors</a>.</p>
<p>Edit your <code>.bash_profile</code> (since OS X 10.8) — or (for 10.7 and earlier): <code>.profile</code> or <code>.bashrc</code> or <... | <p>Here is a solution I've found to enable the global <a href="http://it.toolbox.com/blogs/lim/how-to-fix-colors-on-mac-osx-terminal-37214" rel="noreferrer">terminal colors</a>.</p> <p>Edit your <code>.bash_profile</code> (since OS X 10.8) — or (for 10.7 and earlier): <code>.profile</code> or <code>.bashrc</code> or <... | 369, 390, 391, 6439 | colors, macos, shell, terminal | <h1>OS X Terminal Colors</h1>
<p>I just got a Mac after working with Ubuntu Linux for some time. Among the many things I'm trying to figure out is the absence of colors in my terminal window- like the ones that are shown (on Linux) when running <code>ls -la</code> or <code>git status</code>.</p>
<p>How can one activate... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 201 | bash | # OS X Terminal Colors
I just got a Mac after working with Ubuntu Linux for some time. Among the many things I'm trying to figure out is the absence of colors in my terminal window- like the ones that are shown (on Linux) when running `ls -la` or `git status`.
How can one activate colors in their shell? | Here is a solution I've found to enable the global
[terminal colors](http://it.toolbox.com/blogs/lim/how-to-fix-colors-on-mac-osx-terminal-37214).
Edit your `.bash_profile` (since OS X 10.8) — or (for 10.7 and earlier): `.profile` or `.bashrc` or `/etc/profile` (depending on availability) — in your home directory and ... |
238073 | How to add a progress bar to a shell script? | 563 | 2008-10-26 14:32:05 | <p>When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.</p>
<p>For example, copying a big file, opening a big tar file.</p>
<p>What ways do you recommend to add progress bars to shell scripts?</p>
| 568,860 | 13,523 | 2025-11-18 11:29:30 | 238,094 | 804 | 2008-10-26 14:47:53 | 28,807 | 2018-09-06 01:42:01 | https://stackoverflow.com/q/238073 | https://stackoverflow.com/a/238094 | <p>You can implement this by overwriting a line. Use <code>\r</code> to go back to the beginning of the line without writing <code>\n</code> to the terminal.</p>
<p>Write <code>\n</code> when you're done to advance the line.</p>
<p>Use <code>echo -ne</code> to:</p>
<ol>
<li>not print <code>\n</code> and</li>
<li>to... | <p>You can implement this by overwriting a line. Use <code>\r</code> to go back to the beginning of the line without writing <code>\n</code> to the terminal.</p> <p>Write <code>\n</code> when you're done to advance the line.</p> <p>Use <code>echo -ne</code> to:</p> <ol> <li>not print <code>\n</code> and</li> <li>to... | 387, 390, 3791, 79778 | bash, progress-bar, shell, zsh | <h1>How to add a progress bar to a shell script?</h1>
<p>When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.</p>
<p>For example, copying a big file, opening a big tar file.</p>
<p>What ways do you recommend to add progress bars t... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 202 | bash | # How to add a progress bar to a shell script?
When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.
For example, copying a big file, opening a big tar file.
What ways do you recommend to add progress bars to shell scripts? | You can implement this by overwriting a line. Use `\r` to go back to the beginning of the line without writing `\n` to the terminal.
Write `\n` when you're done to advance the line.
Use `echo -ne` to:
1. not print `\n` and
2. to recognize escape sequences like `\r`.
Here's a demo:
```
echo -ne '##### ... |
125281 | How do I remove the file suffix and path portion from a path string in Bash? | 562 | 2008-09-24 03:37:00 | <p>Given a string file path such as <code>/foo/fizzbuzz.bar</code>, how would I use bash to extract just the <code>fizzbuzz</code> portion of said string?</p>
| 545,174 | 1,512 | 2025-10-15 22:23:18 | 125,340 | 801 | 2008-09-24 03:54:28 | 13,422 | 2025-10-15 22:23:18 | https://stackoverflow.com/q/125281 | https://stackoverflow.com/a/125340 | <p>Here's how to do it with the # and % operators in Bash.</p>
<pre><code>$ x="/foo/fizzbuzz.bar"
$ y=${x%.bar}
$ echo ${y##*/}
fizzbuzz
</code></pre>
<p><code>${x%.bar}</code> could also be <code>${x%.*}</code> to remove everything after the last dot or <code>${x%%.*}</code> to remove everything after the fi... | <p>Here's how to do it with the # and % operators in Bash.</p> <pre><code>$ x="/foo/fizzbuzz.bar" $ y=${x%.bar} $ echo ${y##*/} fizzbuzz </code></pre> <p><code>${x%.bar}</code> could also be <code>${x%.*}</code> to remove everything after the last dot or <code>${x%%.*}</code> to remove everything after the fi... | 139, 387, 1062 | bash, filenames, string | <h1>How do I remove the file suffix and path portion from a path string in Bash?</h1>
<p>Given a string file path such as <code>/foo/fizzbuzz.bar</code>, how would I use bash to extract just the <code>fizzbuzz</code> portion of said string?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 203 | bash | # How do I remove the file suffix and path portion from a path string in Bash?
Given a string file path such as `/foo/fizzbuzz.bar`, how would I use bash to extract just the `fizzbuzz` portion of said string? | Here's how to do it with the # and % operators in Bash.
```
$ x="/foo/fizzbuzz.bar"
$ y=${x%.bar}
$ echo ${y##*/}
fizzbuzz
```
`${x%.bar}` could also be `${x%.*}` to remove everything after the last dot or `${x%%.*}` to remove everything after the first dot.
Example:
```
$ x="/foo/fizzbuzz.bar.quux"
$ y=${x%.*}
$ e... |
17336915 | Return value in a Bash function | 644 | 2013-06-27 07:17:30 | <p>I am working with a bash script and I want to execute a function to print a return value:</p>
<pre><code>function fun1(){
return 34
}
function fun2(){
local res=$(fun1)
echo $res
}
</code></pre>
<p>When I execute <code>fun2</code>, it does not print "34". Why is this the case?</p>
| 909,022 | 2,496,202 | 2025-08-05 09:59:53 | 17,336,953 | 798 | 2013-06-27 07:19:19 | 531,222 | 2021-03-16 16:08:02 | https://stackoverflow.com/q/17336915 | https://stackoverflow.com/a/17336953 | <p>Although Bash has a <code>return</code> statement, the only thing you can specify with it is the function's own <code>exit</code> status (a value between <code>0</code> and <code>255</code>, 0 meaning "success"). So <code>return</code> is not what you want.</p>
<p>You might want to convert your <code>retur... | <p>Although Bash has a <code>return</code> statement, the only thing you can specify with it is the function's own <code>exit</code> status (a value between <code>0</code> and <code>255</code>, 0 meaning "success"). So <code>return</code> is not what you want.</p> <p>You might want to convert your <code>retur... | 387, 5569, 9206 | bash, function, return-value | <h1>Return value in a Bash function</h1>
<p>I am working with a bash script and I want to execute a function to print a return value:</p>
<pre><code>function fun1(){
return 34
}
function fun2(){
local res=$(fun1)
echo $res
}
</code></pre>
<p>When I execute <code>fun2</code>, it does not print "34". Why is this ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 204 | bash | # Return value in a Bash function
I am working with a bash script and I want to execute a function to print a return value:
```
function fun1(){
return 34
}
function fun2(){
local res=$(fun1)
echo $res
}
```
When I execute `fun2`, it does not print "34". Why is this the case? | Although Bash has a `return` statement, the only thing you can specify with it is the function's own `exit` status (a value between `0` and `255`, 0 meaning "success"). So `return` is not what you want.
You might want to convert your `return` statement to an `echo` statement - that way your function output could be ca... |
2371248 | How to convert timestamps to dates in Bash? | 432 | 2010-03-03 12:41:16 | <p>I need a shell command or script that converts a Unix timestamp to a date. The input can come either from the first parameter or from stdin, allowing for the following usage patterns:</p>
<pre><code>ts2date 1267619929
</code></pre>
<p>and</p>
<pre><code>echo 1267619929 | ts2date
</code></pre>
<p>Both commands sh... | 466,989 | 130,121 | 2024-09-30 17:24:08 | 2,371,288 | 798 | 2010-03-03 12:47:51 | 276,138 | 2022-02-19 23:36:39 | https://stackoverflow.com/q/2371248 | https://stackoverflow.com/a/2371288 | <p>On systems with <a href="https://www.gnu.org/software/coreutils/manual/html_node/Seconds-since-the-Epoch.html" rel="noreferrer">GNU Coreutils</a> >= 5.3.0, e.g. Linux you can use:</p>
<pre><code>date -d @1267619929
</code></pre>
| <p>On systems with <a href="https://www.gnu.org/software/coreutils/manual/html_node/Seconds-since-the-Epoch.html" rel="noreferrer">GNU Coreutils</a> >= 5.3.0, e.g. Linux you can use:</p> <pre><code>date -d @1267619929 </code></pre> | 387, 5002, 32842 | bash, date, unix-timestamp | <h1>How to convert timestamps to dates in Bash?</h1>
<p>I need a shell command or script that converts a Unix timestamp to a date. The input can come either from the first parameter or from stdin, allowing for the following usage patterns:</p>
<pre><code>ts2date 1267619929
</code></pre>
<p>and</p>
<pre><code>echo 12... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 205 | bash | # How to convert timestamps to dates in Bash?
I need a shell command or script that converts a Unix timestamp to a date. The input can come either from the first parameter or from stdin, allowing for the following usage patterns:
```
ts2date 1267619929
```
and
```
echo 1267619929 | ts2date
```
Both commands should... | On systems with [GNU Coreutils](https://www.gnu.org/software/coreutils/manual/html_node/Seconds-since-the-Epoch.html) >= 5.3.0, e.g. Linux you can use:
```
date -d @1267619929
``` |
43308319 | How can I run bash in a docker container? | 422 | 2017-04-09 15:07:52 | <p>I am able to run arbitrary shell commands in a container created from docker/whalesay image.</p>
<pre><code>$ docker run docker/whalesay ls -l
total 56
-rw-r--r-- 1 root root 931 May 25 2015 ChangeLog
...
</code></pre>
<p>However, I am unable to run <code>bash</code> in a container created from this image, as the ... | 738,669 | 1,175,080 | 2026-01-07 03:44:56 | 43,309,168 | 788 | 2017-04-09 16:33:47 | 2,449,905 | 2024-05-10 19:44:01 | https://stackoverflow.com/q/43308319 | https://stackoverflow.com/a/43309168 | <p>If you <code>docker run</code> without attaching a tty, and only call <code>bash</code>, then bash finds nothing to do, and it exits. That's because by default, a container is non-interactive, and a shell that runs in non-interactive mode expects a script to run. Absent that, it will exit.</p>
<p>To run a disposable... | <p>If you <code>docker run</code> without attaching a tty, and only call <code>bash</code>, then bash finds nothing to do, and it exits. That's because by default, a container is non-interactive, and a shell that runs in non-interactive mode expects a script to run. Absent that, it will exit.</p> <p>To run a disposable... | 387, 90304 | bash, docker | <h1>How can I run bash in a docker container?</h1>
<p>I am able to run arbitrary shell commands in a container created from docker/whalesay image.</p>
<pre><code>$ docker run docker/whalesay ls -l
total 56
-rw-r--r-- 1 root root 931 May 25 2015 ChangeLog
...
</code></pre>
<p>However, I am unable to run <code>bash</co... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 206 | bash | # How can I run bash in a docker container?
I am able to run arbitrary shell commands in a container created from docker/whalesay image.
```
$ docker run docker/whalesay ls -l
total 56
-rw-r--r-- 1 root root 931 May 25 2015 ChangeLog
...
```
However, I am unable to run `bash` in a container created from this image... | If you `docker run` without attaching a tty, and only call `bash`, then bash finds nothing to do, and it exits. That's because by default, a container is non-interactive, and a shell that runs in non-interactive mode expects a script to run. Absent that, it will exit.
To run a disposable new container, you can simply ... |
525872 | Echo tab characters in bash script | 480 | 2009-02-08 15:05:27 | <p>How do I echo one or more tab characters using a bash script?
When I run this code</p>
<pre><code>res=' 'x # res = "\t\tx"
echo '['$res']' # expect [\t\tx]
</code></pre>
<p>I get this</p>
<pre><code>res=[ x] # that is [<space>x]
</code></pre>
| 718,920 | 52,141 | 2022-05-20 18:46:34 | 525,873 | 784 | 2009-02-08 15:08:03 | 55,925 | 2016-02-16 07:22:22 | https://stackoverflow.com/q/525872 | https://stackoverflow.com/a/525873 | <pre><code>echo -e ' \t '
</code></pre>
<p>will echo 'space tab space newline' (<code>-e</code> means 'enable interpretation of backslash escapes'):</p>
<pre><code>$ echo -e ' \t ' | hexdump -C
00000000 20 09 20 0a | . .|
</code></pre>
| <pre><code>echo -e ' \t ' </code></pre> <p>will echo 'space tab space newline' (<code>-e</code> means 'enable interpretation of backslash escapes'):</p> <pre><code>$ echo -e ' \t ' | hexdump -C 00000000 20 09 20 0a | . .| </code></pre> | 387, 1177, 5162, 13824 | bash, echo, spaces, tabs | <h1>Echo tab characters in bash script</h1>
<p>How do I echo one or more tab characters using a bash script?
When I run this code</p>
<pre><code>res=' 'x # res = "\t\tx"
echo '['$res']' # expect [\t\tx]
</code></pre>
<p>I get this</p>
<pre><code>res=[ x] # that is [<space>x]
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 207 | bash | # Echo tab characters in bash script
How do I echo one or more tab characters using a bash script?
When I run this code
```
res=' 'x # res = "\t\tx"
echo '['$res']' # expect [\t\tx]
```
I get this
```
res=[ x] # that is [<space>x]
``` | ```
echo -e ' \t '
```
will echo 'space tab space newline' (`-e` means 'enable interpretation of backslash escapes'):
```
$ echo -e ' \t ' | hexdump -C
00000000 20 09 20 0a | . .|
``` |
696839 | How do I write a bash script to restart a process if it dies? | 323 | 2009-03-30 11:27:08 | <p>I have a python script that'll be checking a queue and performing an action on each item:</p>
<pre><code># checkqueue.py
while True:
check_queue()
do_something()
</code></pre>
<p>How do I write a bash script that will check if it's running, and if not, start it. Roughly the following pseudo code (or maybe it ... | 337,735 | 3,715 | 2024-08-31 22:42:37 | 697,064 | 782 | 2009-03-30 12:53:53 | 58,803 | 2023-11-22 16:13:22 | https://stackoverflow.com/q/696839 | https://stackoverflow.com/a/697064 | <p>Avoid PID-files, crons, or anything else that tries to evaluate processes that aren't their children.</p>
<p>There is a very good reason why in UNIX, you can ONLY wait on your children. Any method (ps parsing, pgrep, storing a PID, ...) that tries to work around that is flawed and has gaping holes in it. Just say ... | <p>Avoid PID-files, crons, or anything else that tries to evaluate processes that aren't their children.</p> <p>There is a very good reason why in UNIX, you can ONLY wait on your children. Any method (ps parsing, pgrep, storing a PID, ...) that tries to work around that is flawed and has gaping holes in it. Just say ... | 58, 387, 531, 601 | bash, cron, linux, scripting | <h1>How do I write a bash script to restart a process if it dies?</h1>
<p>I have a python script that'll be checking a queue and performing an action on each item:</p>
<pre><code># checkqueue.py
while True:
check_queue()
do_something()
</code></pre>
<p>How do I write a bash script that will check if it's running,... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 208 | bash | # How do I write a bash script to restart a process if it dies?
I have a python script that'll be checking a queue and performing an action on each item:
```
# checkqueue.py
while True:
check_queue()
do_something()
```
How do I write a bash script that will check if it's running, and if not, start it. Roughly th... | Avoid PID-files, crons, or anything else that tries to evaluate processes that aren't their children.
There is a very good reason why in UNIX, you can ONLY wait on your children. Any method (ps parsing, pgrep, storing a PID, ...) that tries to work around that is flawed and has gaping holes in it. Just say **no**.
In... |
7373752 | How do I get cURL to not show the progress bar? | 845 | 2011-09-10 18:30:50 | <p>I'm trying to use cURL in a script and get it to <strong><em>not</em></strong> show the progress bar. </p>
<p>I've tried the <code>-s</code>, <code>-silent</code>, <code>-S</code>, and <code>-quiet</code> options, but none of them work.</p>
<p>Here's a typical command I've tried:</p>
<pre><code>curl -s http://goo... | 576,023 | 458,961 | 2024-12-16 21:46:22 | 7,373,922 | 781 | 2011-09-10 19:04:05 | 190,597 | 2011-09-10 19:04:05 | https://stackoverflow.com/q/7373752 | https://stackoverflow.com/a/7373922 | <pre><code>curl -s http://google.com > temp.html
</code></pre>
<p>works for curl version 7.19.5 on Ubuntu 9.10 (no progress bar). But if for some reason that does not work on your platform, you could always redirect stderr to /dev/null:</p>
<pre><code>curl http://google.com 2>/dev/null > temp.html
</code></... | <pre><code>curl -s http://google.com > temp.html </code></pre> <p>works for curl version 7.19.5 on Ubuntu 9.10 (no progress bar). But if for some reason that does not work on your platform, you could always redirect stderr to /dev/null:</p> <pre><code>curl http://google.com 2>/dev/null > temp.html </code></... | 34, 58, 387, 531, 1554 | bash, curl, linux, scripting, unix | <h1>How do I get cURL to not show the progress bar?</h1>
<p>I'm trying to use cURL in a script and get it to <strong><em>not</em></strong> show the progress bar. </p>
<p>I've tried the <code>-s</code>, <code>-silent</code>, <code>-S</code>, and <code>-quiet</code> options, but none of them work.</p>
<p>Here's a typic... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 209 | bash | # How do I get cURL to not show the progress bar?
I'm trying to use cURL in a script and get it to ***not*** show the progress bar.
I've tried the `-s`, `-silent`, `-S`, and `-quiet` options, but none of them work.
Here's a typical command I've tried:
```
curl -s http://google.com > temp.html
```
I only get the pr... | ```
curl -s http://google.com > temp.html
```
works for curl version 7.19.5 on Ubuntu 9.10 (no progress bar). But if for some reason that does not work on your platform, you could always redirect stderr to /dev/null:
```
curl http://google.com 2>/dev/null > temp.html
``` |
18592173 | Select objects based on value of variable in object using jq | 549 | 2013-09-03 12:19:32 | <p>I have the following json file:</p>
<pre><code>{
"FOO": {
"name": "Donald",
"location": "Stockholm"
},
"BAR": {
"name": "Walt",
"location": "Stockholm"
},
"BAZ&... | 811,194 | 179,444 | 2025-08-08 14:35:33 | 18,608,100 | 781 | 2013-09-04 07:42:01 | 179,444 | 2020-05-09 02:40:21 | https://stackoverflow.com/q/18592173 | https://stackoverflow.com/a/18608100 | <p>Adapted from this post on <a href="https://zerokspot.com/weblog/2013/07/18/processing-json-with-jq/" rel="noreferrer">Processing JSON with jq</a>, you can use the <a href="https://stedolan.github.io/jq/manual/#select(boolean_expression)" rel="noreferrer"><code>select(bool)</code></a> like this:</p>
<pre class="lang... | <p>Adapted from this post on <a href="https://zerokspot.com/weblog/2013/07/18/processing-json-with-jq/" rel="noreferrer">Processing JSON with jq</a>, you can use the <a href="https://stedolan.github.io/jq/manual/#select(boolean_expression)" rel="noreferrer"><code>select(bool)</code></a> like this:</p> <pre class="lang... | 387, 1151, 1508, 105170 | bash, jq, json, select | <h1>Select objects based on value of variable in object using jq</h1>
<p>I have the following json file:</p>
<pre><code>{
"FOO": {
"name": "Donald",
"location": "Stockholm"
},
"BAR": {
"name": "Walt",
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 210 | bash | # Select objects based on value of variable in object using jq
I have the following json file:
```
{
"FOO": {
"name": "Donald",
"location": "Stockholm"
},
"BAR": {
"name": "Walt",
"location": "Stockholm"
},
"BAZ": {
"name": "Jack",
"location": "Where... | Adapted from this post on [Processing JSON with jq](https://zerokspot.com/weblog/2013/07/18/processing-json-with-jq/), you can use the [`select(bool)`](https://stedolan.github.io/jq/manual/#select(boolean_expression)) like this:
```
$ jq '.[] | select(.location=="Stockholm")' json
{
"location": "Stockholm",
"name"... |
4988226 | How do I pass multiple parameters into a function in PowerShell? | 608 | 2011-02-14 01:59:53 | <p>If I have a function which accepts more than one string parameter, the first parameter seems to get all the data assigned to it, and remaining parameters are passed in as empty.</p>
<p>A quick test script:</p>
<pre class="lang-none prettyprint-override"><code>Function Test([string]$arg1, [string]$arg2)
{
Write-H... | 984,548 | 16,522 | 2025-06-08 15:54:32 | 4,988,239 | 780 | 2011-02-14 02:04:06 | 6,920 | 2025-06-08 15:46:57 | https://stackoverflow.com/q/4988226 | https://stackoverflow.com/a/4988239 | <p>Parameters in calls to functions in PowerShell (all versions) <strong>are space-separated, not comma-separated</strong>. Also, the parentheses are entirely unnecessary and will cause a parse error in PowerShell 2.0 (or later) if <a href="https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/s... | <p>Parameters in calls to functions in PowerShell (all versions) <strong>are space-separated, not comma-separated</strong>. Also, the parentheses are entirely unnecessary and will cause a parse error in PowerShell 2.0 (or later) if <a href="https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/s... | 367, 526, 10355 | parameter-passing, powershell, syntax | <h1>How do I pass multiple parameters into a function in PowerShell?</h1>
<p>If I have a function which accepts more than one string parameter, the first parameter seems to get all the data assigned to it, and remaining parameters are passed in as empty.</p>
<p>A quick test script:</p>
<pre class="lang-none prettyprint... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 211 | bash | # How do I pass multiple parameters into a function in PowerShell?
If I have a function which accepts more than one string parameter, the first parameter seems to get all the data assigned to it, and remaining parameters are passed in as empty.
A quick test script:
```
Function Test([string]$arg1, [string]$arg2)
{
... | Parameters in calls to functions in PowerShell (all versions) **are space-separated, not comma-separated**. Also, the parentheses are entirely unnecessary and will cause a parse error in PowerShell 2.0 (or later) if [`Set-StrictMode`](https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/set-str... |
16483119 | An example of how to use getopts in bash | 611 | 2013-05-10 13:12:33 | <p>I want to call <code>myscript</code> file in this way:</p>
<pre><code>$ ./myscript -s 45 -p any_string
</code></pre>
<p>or</p>
<pre><code>$ ./myscript -h #should display help
$ ./myscript #should display help
</code></pre>
<p>My requirements are:</p>
<ul>
<li><code>getopts</code> here to get the input arguments... | 1,038,223 | 1,003,575 | 2024-12-10 03:55:18 | 16,496,491 | 778 | 2013-05-11 11:16:27 | 612,462 | 2013-08-14 14:58:23 | https://stackoverflow.com/q/16483119 | https://stackoverflow.com/a/16496491 | <pre><code>#!/bin/bash
usage() { echo "Usage: $0 [-s <45|90>] [-p <string>]" 1>&2; exit 1; }
while getopts ":s:p:" o; do
case "${o}" in
s)
s=${OPTARG}
((s == 45 || s == 90)) || usage
;;
p)
p=${OPTARG}
;;
*)
... | <pre><code>#!/bin/bash usage() { echo "Usage: $0 [-s <45|90>] [-p <string>]" 1>&2; exit 1; } while getopts ":s:p:" o; do case "${o}" in s) s=${OPTARG} ((s == 45 || s == 90)) || usage ;; p) p=${OPTARG} ;; *) ... | 387, 390, 11225, 19020 | bash, command-line-interface, getopts, shell | <h1>An example of how to use getopts in bash</h1>
<p>I want to call <code>myscript</code> file in this way:</p>
<pre><code>$ ./myscript -s 45 -p any_string
</code></pre>
<p>or</p>
<pre><code>$ ./myscript -h #should display help
$ ./myscript #should display help
</code></pre>
<p>My requirements are:</p>
<ul>
<li><c... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 212 | bash | # An example of how to use getopts in bash
I want to call `myscript` file in this way:
```
$ ./myscript -s 45 -p any_string
```
or
```
$ ./myscript -h #should display help
$ ./myscript #should display help
```
My requirements are:
- `getopts` here to get the input arguments
- check that `-s` exists, if not r... | ```
#!/bin/bash
usage() { echo "Usage: $0 [-s <45|90>] [-p <string>]" 1>&2; exit 1; }
while getopts ":s:p:" o; do
case "${o}" in
s)
s=${OPTARG}
((s == 45 || s == 90)) || usage
;;
p)
p=${OPTARG}
;;
*)
usage
... |
2500436 | How does "cat << EOF" work in bash? | 1,082 | 2010-03-23 13:57:35 | <p>I needed to write a script to enter multi-line input to a program (<code>psql</code>).</p>
<p>After a bit of googling, I found the following syntax works:</p>
<pre><code>cat << EOF | psql ---params
BEGIN;
`pg_dump ----something`
update table .... statement ...;
END;
EOF
</code></pre>
<p>This correctly co... | 1,842,146 | 35,364 | 2025-12-18 13:19:22 | 2,500,451 | 776 | 2010-03-23 13:58:41 | 224,671 | 2017-05-26 04:53:16 | https://stackoverflow.com/q/2500436 | https://stackoverflow.com/a/2500451 | <p>This is called <strong><em>heredoc</strong> format</em> to provide a string into stdin. See <a href="https://en.wikipedia.org/wiki/Here_document#Unix_shells" rel="noreferrer">https://en.wikipedia.org/wiki/Here_document#Unix_shells</a> for more details.</p>
<hr>
<p>From <code>man bash</code>:</p>
<blockquote>
<h... | <p>This is called <strong><em>heredoc</strong> format</em> to provide a string into stdin. See <a href="https://en.wikipedia.org/wiki/Here_document#Unix_shells" rel="noreferrer">https://en.wikipedia.org/wiki/Here_document#Unix_shells</a> for more details.</p> <hr> <p>From <code>man bash</code>:</p> <blockquote> <h... | 58, 387, 531, 7449 | bash, heredoc, linux, scripting | <h1>How does "cat << EOF" work in bash?</h1>
<p>I needed to write a script to enter multi-line input to a program (<code>psql</code>).</p>
<p>After a bit of googling, I found the following syntax works:</p>
<pre><code>cat << EOF | psql ---params
BEGIN;
`pg_dump ----something`
update table .... statement ...;
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 213 | bash | # How does "cat << EOF" work in bash?
I needed to write a script to enter multi-line input to a program (`psql`).
After a bit of googling, I found the following syntax works:
```
cat << EOF | psql ---params
BEGIN;
`pg_dump ----something`
update table .... statement ...;
END;
EOF
```
This correctly constructs the... | This is called ***heredoc*** format to provide a string into stdin. See <https://en.wikipedia.org/wiki/Here_document#Unix_shells> for more details.
---
From `man bash`:
> ## Here Documents
>
> This type of redirection instructs the shell to read input from
> the current source until a line
> containing only word (wi... |
3371294 | How can I recall the argument of the previous bash command? | 443 | 2010-07-30 12:16:17 | <p>Is there a way in Bash to recall the argument of the previous command?</p>
<p>I usually do <code>vi file.c</code> followed by <code>gcc file.c</code>. </p>
<p>Is there a way in Bash to recall the argument of the previous command?</p>
| 147,577 | 406,689 | 2024-07-05 13:02:22 | 3,371,299 | 772 | 2010-07-30 12:17:59 | 227,665 | 2022-11-18 17:30:58 | https://stackoverflow.com/q/3371294 | https://stackoverflow.com/a/3371299 | <p>You can use <code>$_</code> or <code>!$</code> to recall the last argument of the previous command.</p>
<p>Also <kbd>Alt</kbd> + <kbd>.</kbd> can be used to recall the last argument of any of the previous commands.</p>
| <p>You can use <code>$_</code> or <code>!$</code> to recall the last argument of the previous command.</p> <p>Also <kbd>Alt</kbd> + <kbd>.</kbd> can be used to recall the last argument of any of the previous commands.</p> | 34, 58, 387, 1796 | bash, command, linux, unix | <h1>How can I recall the argument of the previous bash command?</h1>
<p>Is there a way in Bash to recall the argument of the previous command?</p>
<p>I usually do <code>vi file.c</code> followed by <code>gcc file.c</code>. </p>
<p>Is there a way in Bash to recall the argument of the previous command?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 214 | bash | # How can I recall the argument of the previous bash command?
Is there a way in Bash to recall the argument of the previous command?
I usually do `vi file.c` followed by `gcc file.c`.
Is there a way in Bash to recall the argument of the previous command? | You can use `$_` or `!$` to recall the last argument of the previous command.
Also `Alt` + `.` can be used to recall the last argument of any of the previous commands. |
160924 | How can I kill a process by name instead of PID, on Linux? | 549 | 2008-10-02 04:57:20 | <p>Sometimes when I try to start Firefox it says "a Firefox process is already running". So I have to do this:</p>
<pre><code>jeremy@jeremy-desktop:~$ ps aux | grep firefox
jeremy 7451 25.0 27.4 170536 65680 ? Sl 22:39 1:18 /usr/lib/firefox-3.0.1/firefox
jeremy 7578 0.0 0.3 3004 768 pts/0 S+ ... | 895,285 | 813 | 2026-01-08 06:25:08 | 160,926 | 770 | 2008-10-02 04:58:24 | 9,611 | 2014-06-27 17:08:48 | https://stackoverflow.com/q/160924 | https://stackoverflow.com/a/160926 | <pre><code>pkill firefox
</code></pre>
<p>More information: <a href="http://linux.about.com/library/cmd/blcmdl1_pkill.htm" rel="noreferrer">http://linux.about.com/library/cmd/blcmdl1_pkill.htm</a></p>
| <pre><code>pkill firefox </code></pre> <p>More information: <a href="http://linux.about.com/library/cmd/blcmdl1_pkill.htm" rel="noreferrer">http://linux.about.com/library/cmd/blcmdl1_pkill.htm</a></p> | 58, 387, 390, 5779 | bash, kill, linux, shell | <h1>How can I kill a process by name instead of PID, on Linux?</h1>
<p>Sometimes when I try to start Firefox it says "a Firefox process is already running". So I have to do this:</p>
<pre><code>jeremy@jeremy-desktop:~$ ps aux | grep firefox
jeremy 7451 25.0 27.4 170536 65680 ? Sl 22:39 1:18 /usr/lib/fire... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 215 | bash | # How can I kill a process by name instead of PID, on Linux?
Sometimes when I try to start Firefox it says "a Firefox process is already running". So I have to do this:
```
jeremy@jeremy-desktop:~$ ps aux | grep firefox
jeremy 7451 25.0 27.4 170536 65680 ? Sl 22:39 1:18 /usr/lib/firefox-3.0.1/firefox
je... | ```
pkill firefox
```
More information: <http://linux.about.com/library/cmd/blcmdl1_pkill.htm> |
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