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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
356100 | How to wait in bash for several subprocesses to finish, and return exit code !=0 when any subprocess ends with code !=0? | 782 | 2008-12-10 13:54:26 | <p>How to wait in a bash script for several subprocesses spawned from that script to finish, and then return exit code <code>!=0</code> when any of the subprocesses ends with code <code>!=0</code>?</p>
<p>Simple script:</p>
<pre><code>#!/bin/bash
for i in `seq 0 9`; do
calculations $i &
done
wait
</code></pre>
<p... | 822,624 | 42,201 | 2024-06-21 16:46:40 | 356,154 | 759 | 2008-12-10 14:07:51 | 42,448 | 2024-06-21 16:46:40 | https://stackoverflow.com/q/356100 | https://stackoverflow.com/a/356154 | <p><a href="https://www.gnu.org/software/bash/manual/html_node/Job-Control-Builtins.html#index-wait" rel="noreferrer"><code>wait</code></a> also (optionally) takes the <code>PID</code> of the process to wait for, and with <code>$!</code> you get the <code>PID</code> of the last command launched in the background.
Modif... | <p><a href="https://www.gnu.org/software/bash/manual/html_node/Job-Control-Builtins.html#index-wait" rel="noreferrer"><code>wait</code></a> also (optionally) takes the <code>PID</code> of the process to wait for, and with <code>$!</code> you get the <code>PID</code> of the last command launched in the background. Modif... | 387, 5910, 21289 | bash, process, wait | <h1>How to wait in bash for several subprocesses to finish, and return exit code !=0 when any subprocess ends with code !=0?</h1>
<p>How to wait in a bash script for several subprocesses spawned from that script to finish, and then return exit code <code>!=0</code> when any of the subprocesses ends with code <code>!=0<... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 216 | bash | # How to wait in bash for several subprocesses to finish, and return exit code !=0 when any subprocess ends with code !=0?
How to wait in a bash script for several subprocesses spawned from that script to finish, and then return exit code `!=0` when any of the subprocesses ends with code `!=0`?
Simple script:
```
#!... | [`wait`](https://www.gnu.org/software/bash/manual/html_node/Job-Control-Builtins.html#index-wait) also (optionally) takes the `PID` of the process to wait for, and with `$!` you get the `PID` of the last command launched in the background.
Modify the loop to store the `PID` of each spawned sub-process into an array, an... |
11287861 | How to check if a file contains a specific string using Bash | 442 | 2012-07-02 04:40:11 | <p>I want to check if a file contains a specific string or not in bash. I used this script, but it doesn't work:</p>
<pre><code> if [[ 'grep 'SomeString' $File' ]];then
# Some Actions
fi
</code></pre>
<p>What's wrong in my code?</p>
| 737,467 | 1,265,960 | 2019-07-23 06:51:10 | 11,287,896 | 759 | 2012-07-02 04:47:14 | 1,458,569 | 2018-01-19 20:02:03 | https://stackoverflow.com/q/11287861 | https://stackoverflow.com/a/11287896 | <pre><code>if grep -q SomeString "$File"; then
Some Actions # SomeString was found
fi
</code></pre>
<p>You don't need <code>[[ ]]</code> here. Just run the command directly. Add <code>-q</code> option when you don't need the string displayed when it was found.</p>
<p>The <code>grep</code> command returns 0 or 1 in ... | <pre><code>if grep -q SomeString "$File"; then Some Actions # SomeString was found fi </code></pre> <p>You don't need <code>[[ ]]</code> here. Just run the command directly. Add <code>-q</code> option when you don't need the string displayed when it was found.</p> <p>The <code>grep</code> command returns 0 or 1 in ... | 387, 390, 1271 | bash, grep, shell | <h1>How to check if a file contains a specific string using Bash</h1>
<p>I want to check if a file contains a specific string or not in bash. I used this script, but it doesn't work:</p>
<pre><code> if [[ 'grep 'SomeString' $File' ]];then
# Some Actions
fi
</code></pre>
<p>What's wrong in my code?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 217 | bash | # How to check if a file contains a specific string using Bash
I want to check if a file contains a specific string or not in bash. I used this script, but it doesn't work:
```
if [[ 'grep 'SomeString' $File' ]];then
# Some Actions
fi
```
What's wrong in my code? | ```
if grep -q SomeString "$File"; then
Some Actions # SomeString was found
fi
```
You don't need `[[ ]]` here. Just run the command directly. Add `-q` option when you don't need the string displayed when it was found.
The `grep` command returns 0 or 1 in the exit code depending on
the result of search. 0 if someth... |
18096670 | What does -z mean in Bash? | 571 | 2013-08-07 07:00:26 | <p>I'm looking at the following code: </p>
<pre><code>if [ -z $2 ]; then
echo "usage: ...
</code></pre>
<p>(The 3 dots are irrelevant usage details.)<br>
Maybe I'm googling it wrong, but I couldn't find an explanation for the <code>-z</code> option.</p>
| 500,963 | 427,653 | 2024-06-26 11:13:27 | 18,096,739 | 754 | 2013-08-07 07:04:01 | 1,009,479 | 2022-11-17 12:11:41 | https://stackoverflow.com/q/18096670 | https://stackoverflow.com/a/18096739 | <p><code>-z string</code>: True if the string is null (an empty string)</p>
<p>See <a href="https://www.gnu.org/software/bash/manual/bash.html#Bash-Conditional-Expressions" rel="noreferrer">https://www.gnu.org/software/bash/manual/bash.html#Bash-Conditional-Expressions</a></p>
| <p><code>-z string</code>: True if the string is null (an empty string)</p> <p>See <a href="https://www.gnu.org/software/bash/manual/bash.html#Bash-Conditional-Expressions" rel="noreferrer">https://www.gnu.org/software/bash/manual/bash.html#Bash-Conditional-Expressions</a></p> | 387 | bash | <h1>What does -z mean in Bash?</h1>
<p>I'm looking at the following code: </p>
<pre><code>if [ -z $2 ]; then
echo "usage: ...
</code></pre>
<p>(The 3 dots are irrelevant usage details.)<br>
Maybe I'm googling it wrong, but I couldn't find an explanation for the <code>-z</code> option.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 218 | bash | # What does -z mean in Bash?
I'm looking at the following code:
```
if [ -z $2 ]; then
echo "usage: ...
```
(The 3 dots are irrelevant usage details.)
Maybe I'm googling it wrong, but I couldn't find an explanation for the `-z` option. | `-z string`: True if the string is null (an empty string)
See <https://www.gnu.org/software/bash/manual/bash.html#Bash-Conditional-Expressions> |
8153750 | How to search a string in multiple files and return the names of files in Powershell? | 477 | 2011-11-16 15:00:29 | <p>I have started learning powershell a couple of days ago, and I couldn't find anything on google that does what I need so please bear with my question.</p>
<p>I have been asked to replace some text strings into multiple files. I do not necessarily know the extension of the possible target files and I don't know thei... | 761,527 | 1,049,905 | 2023-11-30 20:27:05 | 8,153,857 | 754 | 2011-11-16 15:08:33 | 1,021,945 | 2020-01-30 15:42:06 | https://stackoverflow.com/q/8153750 | https://stackoverflow.com/a/8153857 | <p>This should give the location of the files that contain your pattern:</p>
<pre><code>Get-ChildItem -Recurse | Select-String "dummy" -List | Select Path
</code></pre>
| <p>This should give the location of the files that contain your pattern:</p> <pre><code>Get-ChildItem -Recurse | Select-String "dummy" -List | Select Path </code></pre> | 139, 526, 578, 816, 1469 | powershell, recursion, search, string, text | <h1>How to search a string in multiple files and return the names of files in Powershell?</h1>
<p>I have started learning powershell a couple of days ago, and I couldn't find anything on google that does what I need so please bear with my question.</p>
<p>I have been asked to replace some text strings into multiple fi... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 219 | bash | # How to search a string in multiple files and return the names of files in Powershell?
I have started learning powershell a couple of days ago, and I couldn't find anything on google that does what I need so please bear with my question.
I have been asked to replace some text strings into multiple files. I do not ne... | This should give the location of the files that contain your pattern:
```
Get-ChildItem -Recurse | Select-String "dummy" -List | Select Path
``` |
242538 | Unix shell script find out which directory the script file resides? | 700 | 2008-10-28 08:19:24 | <p>Basically I need to run the script with paths related to the shell script file location, how can I change the current directory to the same directory as where the script file resides?</p>
| 752,456 | 16,371 | 2023-06-05 09:11:53 | 242,550 | 753 | 2008-10-28 08:26:03 | 31,099 | 2016-02-28 03:37:38 | https://stackoverflow.com/q/242538 | https://stackoverflow.com/a/242550 | <p>In Bash, you should get what you need like this:</p>
<pre><code>#!/usr/bin/env bash
BASEDIR=$(dirname "$0")
echo "$BASEDIR"
</code></pre>
| <p>In Bash, you should get what you need like this:</p> <pre><code>#!/usr/bin/env bash BASEDIR=$(dirname "$0") echo "$BASEDIR" </code></pre> | 34, 390 | shell, unix | <h1>Unix shell script find out which directory the script file resides?</h1>
<p>Basically I need to run the script with paths related to the shell script file location, how can I change the current directory to the same directory as where the script file resides?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 220 | bash | # Unix shell script find out which directory the script file resides?
Basically I need to run the script with paths related to the shell script file location, how can I change the current directory to the same directory as where the script file resides? | In Bash, you should get what you need like this:
```
#!/usr/bin/env bash
BASEDIR=$(dirname "$0")
echo "$BASEDIR"
``` |
3112687 | How to iterate over associative arrays in Bash | 482 | 2010-06-24 18:07:29 | <p>Based on an associative array in a Bash script, I need to iterate over it to get the key and value.</p>
<pre><code>#!/bin/bash
declare -A array
array[foo]=bar
array[bar]=foo
</code></pre>
<p>I actually don't understand how to get the key while using a for-in loop.</p>
| 298,371 | 231,150 | 2021-01-02 05:18:41 | 3,113,285 | 753 | 2010-06-24 19:31:41 | 26,428 | 2010-06-24 19:31:41 | https://stackoverflow.com/q/3112687 | https://stackoverflow.com/a/3113285 | <p>The keys are accessed using an exclamation point: <code>${!array[@]}</code>, the <strong><em>values</em></strong> are accessed using <code>${array[@]}</code>.</p>
<p>You can iterate over the key/value pairs like this:</p>
<pre><code>for i in "${!array[@]}"
do
echo "key : $i"
echo "value: ${array[$i]}"
done
</... | <p>The keys are accessed using an exclamation point: <code>${!array[@]}</code>, the <strong><em>values</em></strong> are accessed using <code>${array[@]}</code>.</p> <p>You can iterate over the key/value pairs like this:</p> <pre><code>for i in "${!array[@]}" do echo "key : $i" echo "value: ${array[$i]}" done </... | 387, 2575, 13003, 29051 | associative-array, bash, bash4, key-value | <h1>How to iterate over associative arrays in Bash</h1>
<p>Based on an associative array in a Bash script, I need to iterate over it to get the key and value.</p>
<pre><code>#!/bin/bash
declare -A array
array[foo]=bar
array[bar]=foo
</code></pre>
<p>I actually don't understand how to get the key while using a for-in... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 221 | bash | # How to iterate over associative arrays in Bash
Based on an associative array in a Bash script, I need to iterate over it to get the key and value.
```
#!/bin/bash
declare -A array
array[foo]=bar
array[bar]=foo
```
I actually don't understand how to get the key while using a for-in loop. | The keys are accessed using an exclamation point: `${!array[@]}`, the ***values*** are accessed using `${array[@]}`.
You can iterate over the key/value pairs like this:
```
for i in "${!array[@]}"
do
echo "key : $i"
echo "value: ${array[$i]}"
done
```
Note the use of quotes around the variable in the `for` stat... |
878600 | How to create a cron job using Bash automatically without the interactive editor? | 560 | 2009-05-18 16:37:47 | <p>Does <code>crontab</code> have an argument for creating cron jobs without using the editor (<code>crontab -e</code>)? If so, what would be the code to create a cron job from a Bash script?</p>
| 518,466 | 53,797 | 2025-03-03 16:30:14 | 878,647 | 751 | 2009-05-18 16:47:43 | 7,412 | 2016-07-09 15:20:04 | https://stackoverflow.com/q/878600 | https://stackoverflow.com/a/878647 | <p>You can add to the crontab as follows:</p>
<pre><code>#write out current crontab
crontab -l > mycron
#echo new cron into cron file
echo "00 09 * * 1-5 echo hello" >> mycron
#install new cron file
crontab mycron
rm mycron
</code></pre>
<hr>
<h2>Cron line explaination</h2>
<pre><code>* * * * * "command to... | <p>You can add to the crontab as follows:</p> <pre><code>#write out current crontab crontab -l > mycron #echo new cron into cron file echo "00 09 * * 1-5 echo hello" >> mycron #install new cron file crontab mycron rm mycron </code></pre> <hr> <h2>Cron line explaination</h2> <pre><code>* * * * * "command to... | 387, 390, 601 | bash, cron, shell | <h1>How to create a cron job using Bash automatically without the interactive editor?</h1>
<p>Does <code>crontab</code> have an argument for creating cron jobs without using the editor (<code>crontab -e</code>)? If so, what would be the code to create a cron job from a Bash script?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 222 | bash | # How to create a cron job using Bash automatically without the interactive editor?
Does `crontab` have an argument for creating cron jobs without using the editor (`crontab -e`)? If so, what would be the code to create a cron job from a Bash script? | You can add to the crontab as follows:
```
#write out current crontab
crontab -l > mycron
#echo new cron into cron file
echo "00 09 * * 1-5 echo hello" >> mycron
#install new cron file
crontab mycron
rm mycron
```
---
## Cron line explaination
```
* * * * * "command to be executed"
- - - - -
| | | | |
| | | | -----... |
246007 | How to determine whether a given Linux is 32 bit or 64 bit? | 479 | 2008-10-29 06:59:40 | <p>When I type <code>uname -a</code>, it gives the following output.</p>
<pre><code>Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux
</code></pre>
<p>How can I know from this that the given OS is 32 or 64 bit?</p>
<p>This is useful when writing <code>configure</code> script... | 526,782 | 11,602 | 2018-01-05 23:20:29 | 246,014 | 751 | 2008-10-29 07:06:42 | 6,309 | 2017-02-28 03:42:15 | https://stackoverflow.com/q/246007 | https://stackoverflow.com/a/246014 | <p>Try <a href="http://linuxmanpages.net/manpages/fedora16/man1/uname.1.html" rel="noreferrer"><code>uname -m</code></a>. Which is short of <code>uname --machine</code> and it outputs: </p>
<pre><code>x86_64 ==> 64-bit kernel
i686 ==> 32-bit kernel
</code></pre>
<hr>
<p>Otherwise, <strong>not for the Linux k... | <p>Try <a href="http://linuxmanpages.net/manpages/fedora16/man1/uname.1.html" rel="noreferrer"><code>uname -m</code></a>. Which is short of <code>uname --machine</code> and it outputs: </p> <pre><code>x86_64 ==> 64-bit kernel i686 ==> 32-bit kernel </code></pre> <hr> <p>Otherwise, <strong>not for the Linux k... | 58, 390, 5368, 32643 | 32bit-64bit, linux, processor, shell | <h1>How to determine whether a given Linux is 32 bit or 64 bit?</h1>
<p>When I type <code>uname -a</code>, it gives the following output.</p>
<pre><code>Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux
</code></pre>
<p>How can I know from this that the given OS is 32 or 64 b... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 223 | bash | # How to determine whether a given Linux is 32 bit or 64 bit?
When I type `uname -a`, it gives the following output.
```
Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux
```
How can I know from this that the given OS is 32 or 64 bit?
This is useful when writing `configure`... | Try [`uname -m`](http://linuxmanpages.net/manpages/fedora16/man1/uname.1.html). Which is short of `uname --machine` and it outputs:
```
x86_64 ==> 64-bit kernel
i686 ==> 32-bit kernel
```
---
Otherwise, **not for the Linux kernel, but for the CPU**, you type:
```
cat /proc/cpuinfo
```
or:
```
grep flags /proc/c... |
21334348 | How to count items in JSON object using command line? | 471 | 2014-01-24 13:47:19 | <p>I'm getting this kind of <code>JSON</code> reply from a <code>curl</code> command:</p>
<pre><code>[
{
"cid": 49,
"pyn": "yi4",
"hans": "亿",
"hant": "億",
"tid": 68,
"l10n": "cent million",
"pid": 1,
"pos": "num",
"pos_txt": ""
},
{
"cid": 50,
"pyn": "yi4",
"hans"... | 463,774 | 802,365 | 2023-08-16 22:00:28 | 21,355,442 | 747 | 2014-01-25 19:50:26 | 816,157 | 2018-09-25 19:59:10 | https://stackoverflow.com/q/21334348 | https://stackoverflow.com/a/21355442 | <p>Just throwing another solution in the mix...</p>
<p>Try <a href="http://stedolan.github.io/jq/" rel="noreferrer"><code>jq</code></a>, a lightweight and flexible command-line JSON processor:</p>
<pre><code>jq length /tmp/test.json
</code></pre>
<p>Prints the length of the array of objects.</p>
| <p>Just throwing another solution in the mix...</p> <p>Try <a href="http://stedolan.github.io/jq/" rel="noreferrer"><code>jq</code></a>, a lightweight and flexible command-line JSON processor:</p> <pre><code>jq length /tmp/test.json </code></pre> <p>Prints the length of the array of objects.</p> | 387, 1508, 1554, 105170 | bash, curl, jq, json | <h1>How to count items in JSON object using command line?</h1>
<p>I'm getting this kind of <code>JSON</code> reply from a <code>curl</code> command:</p>
<pre><code>[
{
"cid": 49,
"pyn": "yi4",
"hans": "亿",
"hant": "億",
"tid": 68,
"l10n": "cent million",
"pid": 1,
"pos": "num",
"po... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 224 | bash | # How to count items in JSON object using command line?
I'm getting this kind of `JSON` reply from a `curl` command:
```
[
{
"cid": 49,
"pyn": "yi4",
"hans": "亿",
"hant": "億",
"tid": 68,
"l10n": "cent million",
"pid": 1,
"pos": "num",
"pos_txt": ""
},
{
"cid": 50,
"py... | Just throwing another solution in the mix...
Try [`jq`](http://stedolan.github.io/jq/), a lightweight and flexible command-line JSON processor:
```
jq length /tmp/test.json
```
Prints the length of the array of objects. |
1167746 | How can I assign a heredoc value to a variable in Bash? | 570 | 2009-07-22 19:43:31 | <p>I have this multi-line string (quotes included):</p>
<pre><code>abc'asdf"
$(dont-execute-this)
foo"bar"''
</code></pre>
<p>How would I assign it to a variable using a heredoc in Bash?</p>
<p>I need to preserve newlines.</p>
<p>I don't want to escape the characters in the string. That would be annoying... | 327,860 | 14,193 | 2025-04-28 19:46:18 | 1,655,389 | 745 | 2009-10-31 19:41:21 | 26,428 | 2024-11-14 14:58:37 | https://stackoverflow.com/q/1167746 | https://stackoverflow.com/a/1655389 | <p>You can avoid a useless use of <code>cat</code> and handle mismatched quotes better with this:</p>
<pre><code>$ read -r -d '' VAR <<'EOF'
abc'asdf"
$(dont-execute-this)
foo"bar"''
EOF
</code></pre>
<p>If you don't quote the variable when you echo it, newlines are lost. Quoting it preserves them:... | <p>You can avoid a useless use of <code>cat</code> and handle mismatched quotes better with this:</p> <pre><code>$ read -r -d '' VAR <<'EOF' abc'asdf" $(dont-execute-this) foo"bar"'' EOF </code></pre> <p>If you don't quote the variable when you echo it, newlines are lost. Quoting it preserves them:... | 387, 7449 | bash, heredoc | <h1>How can I assign a heredoc value to a variable in Bash?</h1>
<p>I have this multi-line string (quotes included):</p>
<pre><code>abc'asdf"
$(dont-execute-this)
foo"bar"''
</code></pre>
<p>How would I assign it to a variable using a heredoc in Bash?</p>
<p>I need to preserve newlines.</p>
<p>I don't wa... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 225 | bash | # How can I assign a heredoc value to a variable in Bash?
I have this multi-line string (quotes included):
```
abc'asdf"
$(dont-execute-this)
foo"bar"''
```
How would I assign it to a variable using a heredoc in Bash?
I need to preserve newlines.
I don't want to escape the characters in the string. That would be a... | You can avoid a useless use of `cat` and handle mismatched quotes better with this:
```
$ read -r -d '' VAR <<'EOF'
abc'asdf"
$(dont-execute-this)
foo"bar"''
EOF
```
If you don't quote the variable when you echo it, newlines are lost. Quoting it preserves them:
```
$ echo "$VAR"
abc'asdf"
$(dont-execute-this)
foo"ba... |
20381128 | Installing Homebrew on macOS | 367 | 2013-12-04 16:47:16 | <p>According to the Homebrew site, to install it, I need to type:</p>
<pre><code>brew install wget
</code></pre>
<p>I get an error message:</p>
<pre><code>-bash: brew: command not found
</code></pre>
<p>Found <a href="https://stackoverflow.com/questions/14288682/error-installing-homebrew-brew-command-not-found">this an... | 807,374 | 1,472,743 | 2025-03-10 23:17:31 | 20,381,183 | 745 | 2013-12-04 16:49:12 | 263,104 | 2021-05-24 14:12:05 | https://stackoverflow.com/q/20381128 | https://stackoverflow.com/a/20381183 | <p>It's on the top of the <a href="http://brew.sh/" rel="noreferrer">Homebrew homepage</a>.</p>
<p>From a Terminal prompt:</p>
<pre><code>/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
</code></pre>
<p>The command <code>brew install wget</code> is an example ... | <p>It's on the top of the <a href="http://brew.sh/" rel="noreferrer">Homebrew homepage</a>.</p> <p>From a Terminal prompt:</p> <pre><code>/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)" </code></pre> <p>The command <code>brew install wget</code> is an example ... | 369, 387, 529, 1067 | bash, homebrew, installation, macos | <h1>Installing Homebrew on macOS</h1>
<p>According to the Homebrew site, to install it, I need to type:</p>
<pre><code>brew install wget
</code></pre>
<p>I get an error message:</p>
<pre><code>-bash: brew: command not found
</code></pre>
<p>Found <a href="https://stackoverflow.com/questions/14288682/error-installing-ho... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 226 | bash | # Installing Homebrew on macOS
According to the Homebrew site, to install it, I need to type:
```
brew install wget
```
I get an error message:
```
-bash: brew: command not found
```
Found [this answer](https://stackoverflow.com/questions/14288682/error-installing-homebrew-brew-command-not-found). The problem, how... | It's on the top of the [Homebrew homepage](http://brew.sh/).
From a Terminal prompt:
```
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
```
The command `brew install wget` is an example of how to use Homebrew to install another application (in this case, `wget`) aft... |
18599711 | How can I split a shell command over multiple lines when using an IF statement? | 520 | 2013-09-03 19:10:19 | <p>How can I split a command over multiple lines in the shell, when the command is part of an <code>if</code> statement?</p>
<p>This works: </p>
<pre><code>if ! fab --fabfile=.deploy/fabfile.py --forward-agent --disable-known-hosts deploy:$target; then rc=1 ... | 577,656 | 741,970 | 2022-01-16 15:41:15 | 18,599,906 | 741 | 2013-09-03 19:22:45 | 797,049 | 2022-01-16 15:41:15 | https://stackoverflow.com/q/18599711 | https://stackoverflow.com/a/18599906 | <p>The line-continuation will fail if you have whitespace (spaces or tab characters¹) after the backslash and before the newline. With no such whitespace, your example works fine for me:</p>
<pre><code>$ cat test.sh
if ! fab --fabfile=.deploy/fabfile.py \
--forward-agent \
--disable-known-hosts deploy:$target; th... | <p>The line-continuation will fail if you have whitespace (spaces or tab characters¹) after the backslash and before the newline. With no such whitespace, your example works fine for me:</p> <pre><code>$ cat test.sh if ! fab --fabfile=.deploy/fabfile.py \ --forward-agent \ --disable-known-hosts deploy:$target; th... | 367, 10327 | sh, syntax | <h1>How can I split a shell command over multiple lines when using an IF statement?</h1>
<p>How can I split a command over multiple lines in the shell, when the command is part of an <code>if</code> statement?</p>
<p>This works: </p>
<pre><code>if ! fab --fabfile=.deploy/fabfile.py --forward-agent --disable-known-hos... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 227 | bash | # How can I split a shell command over multiple lines when using an IF statement?
How can I split a command over multiple lines in the shell, when the command is part of an `if` statement?
This works:
```
if ! fab --fabfile=.deploy/fabfile.py --forward-agent --disable-known-hosts deploy:$target; then rc=1 ... | The line-continuation will fail if you have whitespace (spaces or tab characters¹) after the backslash and before the newline. With no such whitespace, your example works fine for me:
```
$ cat test.sh
if ! fab --fabfile=.deploy/fabfile.py \
--forward-agent \
--disable-known-hosts deploy:$target; then
echo ... |
40944479 | How to use bash with an Alpine based docker image? | 481 | 2016-12-03 05:14:18 | <p>I created a docker image from <code>openjdk:8-jdk-alpine</code> and I want to use <code>bash</code>, rather than <code>sh</code> as my shell, however when I try to execute simple commands I get the following errors:</p>
<pre><code>RUN bash
/bin/sh: bash: not found
RUN ./gradlew build
env: can't execute 'bash': No s... | 492,917 | 4,830,460 | 2025-08-16 17:59:24 | 40,944,512 | 741 | 2016-12-03 05:18:06 | 548,225 | 2022-09-04 21:34:15 | https://stackoverflow.com/q/40944479 | https://stackoverflow.com/a/40944512 | <p>Alpine docker image doesn't have bash installed by default. You will need to add the following commands to get <code>bash</code>:</p>
<pre><code>RUN apk update && apk add bash
</code></pre>
<p>If you're using <code>Alpine 3.3+</code> then you can just do:</p>
<pre><code>RUN apk add --no-cache bash
</code></p... | <p>Alpine docker image doesn't have bash installed by default. You will need to add the following commands to get <code>bash</code>:</p> <pre><code>RUN apk update && apk add bash </code></pre> <p>If you're using <code>Alpine 3.3+</code> then you can just do:</p> <pre><code>RUN apk add --no-cache bash </code></p... | 387, 390, 90304, 115689 | alpine-linux, bash, docker, shell | <h1>How to use bash with an Alpine based docker image?</h1>
<p>I created a docker image from <code>openjdk:8-jdk-alpine</code> and I want to use <code>bash</code>, rather than <code>sh</code> as my shell, however when I try to execute simple commands I get the following errors:</p>
<pre><code>RUN bash
/bin/sh: bash: no... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 228 | bash | # How to use bash with an Alpine based docker image?
I created a docker image from `openjdk:8-jdk-alpine` and I want to use `bash`, rather than `sh` as my shell, however when I try to execute simple commands I get the following errors:
```
RUN bash
/bin/sh: bash: not found
RUN ./gradlew build
env: can't execute 'bas... | Alpine docker image doesn't have bash installed by default. You will need to add the following commands to get `bash`:
```
RUN apk update && apk add bash
```
If you're using `Alpine 3.3+` then you can just do:
```
RUN apk add --no-cache bash
```
To keep the docker image size small. (Thanks to comment from @sprkysnr... |
3983406 | vim: how to delete a newline/linefeed character(s)? | 358 | 2010-10-21 00:32:15 | <p>Is there a way to delete the newline at the end of a line in Vim, so that the next line is appended to the current line?</p>
<p>For example:</p>
<pre><code>Evaluator<T>():
_bestPos(){
}
</code></pre>
<p>I'd like to put this all on one line without copying lines and pasting them into the previous one. I... | 286,963 | 247,763 | 2024-02-19 03:50:01 | 3,983,437 | 739 | 2010-10-21 00:39:04 | 476,895 | 2016-09-07 14:48:06 | https://stackoverflow.com/q/3983406 | https://stackoverflow.com/a/3983437 | <p>If you are on the first line, pressing (upper case) <kbd>J</kbd> will join that line and the next line together, removing the newline. You can also combine this with a count, so pressing <code>3J</code> will combine all 3 lines together.</p>
| <p>If you are on the first line, pressing (upper case) <kbd>J</kbd> will join that line and the next line together, removing the newline. You can also combine this with a count, so pressing <code>3J</code> will combine all 3 lines together.</p> | 34, 293, 370, 386, 390 | shell, ssh, unix, vi, vim | <h1>vim: how to delete a newline/linefeed character(s)?</h1>
<p>Is there a way to delete the newline at the end of a line in Vim, so that the next line is appended to the current line?</p>
<p>For example:</p>
<pre><code>Evaluator<T>():
_bestPos(){
}
</code></pre>
<p>I'd like to put this all on one line wit... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 229 | bash | # vim: how to delete a newline/linefeed character(s)?
Is there a way to delete the newline at the end of a line in Vim, so that the next line is appended to the current line?
For example:
```
Evaluator<T>():
_bestPos(){
}
```
I'd like to put this all on one line without copying lines and pasting them into the p... | If you are on the first line, pressing (upper case) `J` will join that line and the next line together, removing the newline. You can also combine this with a count, so pressing `3J` will combine all 3 lines together. |
2961635 | Using awk to print all columns from the nth to the last | 484 | 2010-06-02 21:13:03 | <p>This line worked until I had whitespace in the second field:</p>
<pre><code>svn status | grep '\!' | gawk '{print $2;}' > removedProjs
</code></pre>
<p>Is there a way to have <code>awk</code> print everything in <code>$2</code> or greater? (<code>$3</code>, <code>$4</code>.. until we don't have any more columns?... | 703,125 | 275,354 | 2025-09-05 20:16:03 | 2,961,994 | 725 | 2010-06-02 22:10:36 | 286,595 | 2021-03-13 05:20:46 | https://stackoverflow.com/q/2961635 | https://stackoverflow.com/a/2961994 | <p>Print all columns:</p>
<pre><code>awk '{print $0}' somefile
</code></pre>
<p>Print all but the first column:</p>
<pre><code>awk '{$1=""; print $0}' somefile
</code></pre>
<p>Print all but the first two columns:</p>
<pre><code>awk '{$1=$2=""; print $0}' somefile
</code></pre>
| <p>Print all columns:</p> <pre><code>awk '{print $0}' somefile </code></pre> <p>Print all but the first column:</p> <pre><code>awk '{$1=""; print $0}' somefile </code></pre> <p>Print all but the first two columns:</p> <pre><code>awk '{$1=$2=""; print $0}' somefile </code></pre> | 58, 390, 990, 1731 | awk, cygwin, linux, shell | <h1>Using awk to print all columns from the nth to the last</h1>
<p>This line worked until I had whitespace in the second field:</p>
<pre><code>svn status | grep '\!' | gawk '{print $2;}' > removedProjs
</code></pre>
<p>Is there a way to have <code>awk</code> print everything in <code>$2</code> or greater? (<code>$... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 230 | bash | # Using awk to print all columns from the nth to the last
This line worked until I had whitespace in the second field:
```
svn status | grep '\!' | gawk '{print $2;}' > removedProjs
```
Is there a way to have `awk` print everything in `$2` or greater? (`$3`, `$4`.. until we don't have any more columns?)
I'm doing t... | Print all columns:
```
awk '{print $0}' somefile
```
Print all but the first column:
```
awk '{$1=""; print $0}' somefile
```
Print all but the first two columns:
```
awk '{$1=$2=""; print $0}' somefile
``` |
2188199 | How to use double or single brackets, parentheses, curly braces | 804 | 2010-02-02 22:22:54 | <p>I am confused by the usage of brackets, parentheses, curly braces in Bash, as well as the difference between their double or single forms. Is there a clear explanation?</p>
| 492,885 | 156,458 | 2024-10-29 22:41:30 | 2,188,369 | 723 | 2010-02-02 22:48:42 | 26,428 | 2023-08-01 18:01:36 | https://stackoverflow.com/q/2188199 | https://stackoverflow.com/a/2188369 | <p>In Bash, <code>test</code> and <code>[</code> are shell builtins.</p>
<p>The <a href="http://mywiki.wooledge.org/BashFAQ/031" rel="noreferrer">double bracket</a> <code>[[</code>, which is a shell keyword, enables additional functionality. For example, you can use <code>&&</code> and <code>||</code> instead o... | <p>In Bash, <code>test</code> and <code>[</code> are shell builtins.</p> <p>The <a href="http://mywiki.wooledge.org/BashFAQ/031" rel="noreferrer">double bracket</a> <code>[[</code>, which is a shell keyword, enables additional functionality. For example, you can use <code>&&</code> and <code>||</code> instead o... | 367, 387 | bash, syntax | <h1>How to use double or single brackets, parentheses, curly braces</h1>
<p>I am confused by the usage of brackets, parentheses, curly braces in Bash, as well as the difference between their double or single forms. Is there a clear explanation?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 231 | bash | # How to use double or single brackets, parentheses, curly braces
I am confused by the usage of brackets, parentheses, curly braces in Bash, as well as the difference between their double or single forms. Is there a clear explanation? | In Bash, `test` and `[` are shell builtins.
The [double bracket](http://mywiki.wooledge.org/BashFAQ/031) `[[`, which is a shell keyword, enables additional functionality. For example, you can use `&&` and `||` instead of `-a` and `-o` and there's a regular expression matching operator `=~`.
Also, in a simple test, do... |
1891797 | Capturing Groups From a Grep RegEx | 541 | 2009-12-12 00:55:14 | <p>I've got this script in <code>sh</code> (macOS 10.6) to look through an array of files:</p>
<pre><code>files="*.jpg"
for f in $files
do
echo $f | grep -oEi '[0-9]+_([a-z]+)_[0-9a-z]*'
name=$?
echo $name
done
</code></pre>
<p>So far <code>$name</code> merely holds 0, 1 or 2, ... | 699,902 | 142,240 | 2024-07-11 21:54:01 | 1,892,107 | 717 | 2009-12-12 02:59:03 | 26,428 | 2024-01-09 16:26:03 | https://stackoverflow.com/q/1891797 | https://stackoverflow.com/a/1892107 | <p>If you're using Bash, you don't even have to use <code>grep</code>:</p>
<pre><code>files="*.jpg"
regex="[0-9]+_([a-z]+)_[0-9a-z]*" # put the regex in a variable because some patterns won't work if included literally
for f in $files # unquoted in order to allow the glob to expand
do
if [[ $... | <p>If you're using Bash, you don't even have to use <code>grep</code>:</p> <pre><code>files="*.jpg" regex="[0-9]+_([a-z]+)_[0-9a-z]*" # put the regex in a variable because some patterns won't work if included literally for f in $files # unquoted in order to allow the glob to expand do if [[ $... | 387, 390, 1271 | bash, grep, shell | <h1>Capturing Groups From a Grep RegEx</h1>
<p>I've got this script in <code>sh</code> (macOS 10.6) to look through an array of files:</p>
<pre><code>files="*.jpg"
for f in $files
do
echo $f | grep -oEi '[0-9]+_([a-z]+)_[0-9a-z]*'
name=$?
echo $name
done
</code></pre>
<p>So far... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 232 | bash | # Capturing Groups From a Grep RegEx
I've got this script in `sh` (macOS 10.6) to look through an array of files:
```
files="*.jpg"
for f in $files
do
echo $f | grep -oEi '[0-9]+_([a-z]+)_[0-9a-z]*'
name=$?
echo $name
done
```
So far `$name` merely holds 0, 1 or 2, depending on if `gr... | If you're using Bash, you don't even have to use `grep`:
```
files="*.jpg"
regex="[0-9]+_([a-z]+)_[0-9a-z]*" # put the regex in a variable because some patterns won't work if included literally
for f in $files # unquoted in order to allow the glob to expand
do
if [[ $f =~ $regex ]]
then
name="${BASH... |
13738634 | How can I check if a string is null or empty in PowerShell? | 646 | 2012-12-06 07:09:28 | <p>Is there a built-in <code>IsNullOrEmpty</code>-like function in order to check if a string is null or empty, in PowerShell?</p>
<p>I could not find it so far and if there is a built-in way, I do not want to write a function for this.</p>
| 1,027,825 | 136,141 | 2023-11-21 06:04:15 | 13,739,113 | 716 | 2012-12-06 07:48:30 | 9,833 | 2014-03-06 08:00:36 | https://stackoverflow.com/q/13738634 | https://stackoverflow.com/a/13739113 | <p>You can use the <code>IsNullOrEmpty</code> static method:</p>
<pre><code>[string]::IsNullOrEmpty(...)
</code></pre>
| <p>You can use the <code>IsNullOrEmpty</code> static method:</p> <pre><code>[string]::IsNullOrEmpty(...) </code></pre> | 1, 139, 526, 694 | .net, null, powershell, string | <h1>How can I check if a string is null or empty in PowerShell?</h1>
<p>Is there a built-in <code>IsNullOrEmpty</code>-like function in order to check if a string is null or empty, in PowerShell?</p>
<p>I could not find it so far and if there is a built-in way, I do not want to write a function for this.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 233 | bash | # How can I check if a string is null or empty in PowerShell?
Is there a built-in `IsNullOrEmpty`-like function in order to check if a string is null or empty, in PowerShell?
I could not find it so far and if there is a built-in way, I do not want to write a function for this. | You can use the `IsNullOrEmpty` static method:
```
[string]::IsNullOrEmpty(...)
``` |
8095638 | How do I negate a condition in PowerShell? | 404 | 2011-11-11 14:50:10 | <p>How do I negate a conditional test in PowerShell?</p>
<p>For example, if I want to check for the directory C:\Code, I can run:</p>
<pre><code>if (Test-Path C:\Code){
write "it exists!"
}
</code></pre>
<p>Is there a way to negate that condition, e.g. (non-working):</p>
<pre><code>if (Not (Test-Path C:\Code)){
... | 478,837 | 166,258 | 2025-12-29 19:57:40 | 8,095,680 | 716 | 2011-11-11 14:54:03 | 291,709 | 2025-10-08 18:07:41 | https://stackoverflow.com/q/8095638 | https://stackoverflow.com/a/8095680 | <p>You almost had it with <code>Not</code>. It should be:</p>
<pre><code>if (-Not (Test-Path C:\Code)) {
write "it doesn't exist!"
}
</code></pre>
<p>You can also use <code>!</code>:</p>
<pre><code>if (!(Test-Path C:\Code)){}`
</code></pre>
<p>Note that <code>!</code> above <strong>requires</strong> an a... | <p>You almost had it with <code>Not</code>. It should be:</p> <pre><code>if (-Not (Test-Path C:\Code)) { write "it doesn't exist!" } </code></pre> <p>You can also use <code>!</code>:</p> <pre><code>if (!(Test-Path C:\Code)){}` </code></pre> <p>Note that <code>!</code> above <strong>requires</strong> an a... | 64, 526 | powershell, windows | <h1>How do I negate a condition in PowerShell?</h1>
<p>How do I negate a conditional test in PowerShell?</p>
<p>For example, if I want to check for the directory C:\Code, I can run:</p>
<pre><code>if (Test-Path C:\Code){
write "it exists!"
}
</code></pre>
<p>Is there a way to negate that condition, e.g. (non-worki... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 234 | bash | # How do I negate a condition in PowerShell?
How do I negate a conditional test in PowerShell?
For example, if I want to check for the directory C:\Code, I can run:
```
if (Test-Path C:\Code){
write "it exists!"
}
```
Is there a way to negate that condition, e.g. (non-working):
```
if (Not (Test-Path C:\Code)){
... | You almost had it with `Not`. It should be:
```
if (-Not (Test-Path C:\Code)) {
write "it doesn't exist!"
}
```
You can also use `!`:
```
if (!(Test-Path C:\Code)){}`
```
Note that `!` above **requires** an additional set of parentheses around the negated conditional statement; `if !(Test-path C:\Code) {}` will... |
3213748 | Get line number while using grep | 478 | 2010-07-09 14:49:26 | <p>I am using grep recursive to search files for a string, and all the matched files and the lines containing that string are printed on the terminal. But is it possible to get the line numbers of those lines too?</p>
<p>Example: presently, I get <code>/var/www/file.php: $options = "this.target"</code>, but I... | 553,763 | 320,755 | 2024-01-28 05:29:56 | 3,213,773 | 715 | 2010-07-09 14:52:26 | 369,692 | 2020-05-10 14:10:37 | https://stackoverflow.com/q/3213748 | https://stackoverflow.com/a/3213773 | <pre><code>grep -n SEARCHTERM file1 file2 ...
</code></pre>
| <pre><code>grep -n SEARCHTERM file1 file2 ... </code></pre> | 58, 390, 1271, 9325 | grep, line, linux, shell | <h1>Get line number while using grep</h1>
<p>I am using grep recursive to search files for a string, and all the matched files and the lines containing that string are printed on the terminal. But is it possible to get the line numbers of those lines too?</p>
<p>Example: presently, I get <code>/var/www/file.php: $optio... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 235 | bash | # Get line number while using grep
I am using grep recursive to search files for a string, and all the matched files and the lines containing that string are printed on the terminal. But is it possible to get the line numbers of those lines too?
Example: presently, I get `/var/www/file.php: $options = "this.target"`,... | ```
grep -n SEARCHTERM file1 file2 ...
``` |
8903239 | How can I calculate time elapsed in a Bash script? | 335 | 2012-01-17 23:38:54 | <p>I print the start and end time using <code>date +"%T"</code>, which results in something like:</p>
<pre><code>10:33:56
10:36:10
</code></pre>
<p>How could I calculate and print the difference between these two?</p>
<p>I would like to get something like:</p>
<pre><code>2m 14s
</code></pre>
| 436,105 | 247,243 | 2025-03-13 16:14:00 | 8,903,280 | 715 | 2012-01-17 23:44:07 | 1,155,000 | 2024-03-13 01:39:16 | https://stackoverflow.com/q/8903239 | https://stackoverflow.com/a/8903280 | <p>Bash has a handy <code>SECONDS</code> builtin variable that tracks the number of seconds that have passed since the shell was started. This variable retains its properties when assigned to, and the value returned after the assignment is the number of seconds since the assignment plus the assigned value.</p>
<p>Thus,... | <p>Bash has a handy <code>SECONDS</code> builtin variable that tracks the number of seconds that have passed since the shell was started. This variable retains its properties when assigned to, and the value returned after the assignment is the number of seconds since the assignment plus the assigned value.</p> <p>Thus,... | 387, 5002 | bash, date | <h1>How can I calculate time elapsed in a Bash script?</h1>
<p>I print the start and end time using <code>date +"%T"</code>, which results in something like:</p>
<pre><code>10:33:56
10:36:10
</code></pre>
<p>How could I calculate and print the difference between these two?</p>
<p>I would like to get something... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 236 | bash | # How can I calculate time elapsed in a Bash script?
I print the start and end time using `date +"%T"`, which results in something like:
```
10:33:56
10:36:10
```
How could I calculate and print the difference between these two?
I would like to get something like:
```
2m 14s
``` | Bash has a handy `SECONDS` builtin variable that tracks the number of seconds that have passed since the shell was started. This variable retains its properties when assigned to, and the value returned after the assignment is the number of seconds since the assignment plus the assigned value.
Thus, you can just set `S... |
36273665 | What does `set -x` do? | 498 | 2016-03-29 00:58:08 | <p>I have a shell script with the following line in it:</p>
<pre><code>[ "$DEBUG" == 'true' ] && set -x
</code></pre>
| 416,474 | 1,684,269 | 2024-07-28 14:42:43 | 36,273,740 | 710 | 2016-03-29 01:07:25 | 4,323 | 2024-07-28 14:42:43 | https://stackoverflow.com/q/36273665 | https://stackoverflow.com/a/36273740 | <p><code>set -x</code> enables a shell mode where all executed commands are printed to the terminal.</p>
<p>In your case it's used for debugging, which is a typical use case for <code>set -x</code>: printing every command as it is executed may help you visualize the script's control flow if it is not functioning as exp... | <p><code>set -x</code> enables a shell mode where all executed commands are printed to the terminal.</p> <p>In your case it's used for debugging, which is a typical use case for <code>set -x</code>: printing every command as it is executed may help you visualize the script's control flow if it is not functioning as exp... | 34, 390, 531 | scripting, shell, unix | <h1>What does `set -x` do?</h1>
<p>I have a shell script with the following line in it:</p>
<pre><code>[ "$DEBUG" == 'true' ] && set -x
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 237 | bash | # What does `set -x` do?
I have a shell script with the following line in it:
```
[ "$DEBUG" == 'true' ] && set -x
``` | `set -x` enables a shell mode where all executed commands are printed to the terminal.
In your case it's used for debugging, which is a typical use case for `set -x`: printing every command as it is executed may help you visualize the script's control flow if it is not functioning as expected.
`set +x` disables it. |
8586648 | Going to a specific line number using Less in Unix | 513 | 2011-12-21 08:04:01 | <p>I have a file that has around million lines. I need to go to line number 320123 to check the data. How do I do that?</p>
| 394,521 | 386,946 | 2023-10-05 10:43:48 | 8,586,690 | 708 | 2011-12-21 08:08:03 | 275,431 | 2014-09-15 15:20:19 | https://stackoverflow.com/q/8586648 | https://stackoverflow.com/a/8586690 | <p>With <code>n</code> being the line number:</p>
<ul>
<li><code>ng</code>: Jump to line number n. Default is the start of the file.</li>
<li><code>nG</code>: Jump to line number n. Default is the end of the file.</li>
</ul>
<p>So to go to line number 320123, you would type <code>320123g</code>.</p>
<p>Copy-pasted s... | <p>With <code>n</code> being the line number:</p> <ul> <li><code>ng</code>: Jump to line number n. Default is the start of the file.</li> <li><code>nG</code>: Jump to line number n. Default is the end of the file.</li> </ul> <p>So to go to line number 320123, you would type <code>320123g</code>.</p> <p>Copy-pasted s... | 34, 390, 816, 126205 | less-unix, search, shell, unix | <h1>Going to a specific line number using Less in Unix</h1>
<p>I have a file that has around million lines. I need to go to line number 320123 to check the data. How do 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 | 238 | bash | # Going to a specific line number using Less in Unix
I have a file that has around million lines. I need to go to line number 320123 to check the data. How do I do that? | With `n` being the line number:
- `ng`: Jump to line number n. Default is the start of the file.
- `nG`: Jump to line number n. Default is the end of the file.
So to go to line number 320123, you would type `320123g`.
Copy-pasted straight from [Wikipedia](http://en.wikipedia.org/wiki/Less_(Unix)). |
255414 | Why can't I change directories using "cd" in a script? | 840 | 2008-11-01 02:07:08 | <p>I'm trying to write a small script to change the current directory to my project directory:</p>
<pre><code>#!/bin/bash
cd /home/tree/projects/java
</code></pre>
<p>I saved this file as proj, added execute permission with <code>chmod</code>, and copied it to <code>/usr/bin</code>. When I call it by:
<code>proj</cod... | 779,356 | 33,203 | 2024-07-18 02:27:41 | 255,415 | 707 | 2008-11-01 02:09:06 | 893 | 2014-05-08 13:18:46 | https://stackoverflow.com/q/255414 | https://stackoverflow.com/a/255415 | <p>Shell scripts are run inside a subshell, and each subshell has its own concept of what the current directory is. The <code>cd</code> succeeds, but as soon as the subshell exits, you're back in the interactive shell and nothing ever changed there.</p>
<p>One way to get around this is to use an alias instead:</p>
<p... | <p>Shell scripts are run inside a subshell, and each subshell has its own concept of what the current directory is. The <code>cd</code> succeeds, but as soon as the subshell exits, you're back in the interactive shell and nothing ever changed there.</p> <p>One way to get around this is to use an alias instead:</p> <p... | 58, 387, 390 | bash, linux, shell | <h1>Why can't I change directories using "cd" in a script?</h1>
<p>I'm trying to write a small script to change the current directory to my project directory:</p>
<pre><code>#!/bin/bash
cd /home/tree/projects/java
</code></pre>
<p>I saved this file as proj, added execute permission with <code>chmod</code>, and copied... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 239 | bash | # Why can't I change directories using "cd" in a script?
I'm trying to write a small script to change the current directory to my project directory:
```
#!/bin/bash
cd /home/tree/projects/java
```
I saved this file as proj, added execute permission with `chmod`, and copied it to `/usr/bin`. When I call it by:
`proj`... | Shell scripts are run inside a subshell, and each subshell has its own concept of what the current directory is. The `cd` succeeds, but as soon as the subshell exits, you're back in the interactive shell and nothing ever changed there.
One way to get around this is to use an alias instead:
```
alias proj="cd /home/tr... |
1765311 | How to view files in binary from bash? | 410 | 2009-11-19 18:04:11 | <p>I would like to view the contents of a file in the current directory, but in binary from the command line. How can I achieve this?</p>
<p>For example, something like this:</p>
<pre class="lang-none prettyprint-override"><code>$ cat test
Hello, world!
$ binarycat test
01001000 01100101 01101100 01101100 01101111 001... | 627,783 | 211,176 | 2025-12-02 16:22:44 | 20,305,782 | 707 | 2013-11-30 21:20:58 | 1,409,834 | 2020-04-10 08:47:10 | https://stackoverflow.com/q/1765311 | https://stackoverflow.com/a/20305782 | <p><a href="https://linux.die.net/man/1/xxd" rel="noreferrer"><code>xxd</code></a> does both binary and hexadecimal.</p>
<p>bin:</p>
<pre><code>xxd -b file
</code></pre>
<p>hex:</p>
<pre><code>xxd file
</code></pre>
| <p><a href="https://linux.die.net/man/1/xxd" rel="noreferrer"><code>xxd</code></a> does both binary and hexadecimal.</p> <p>bin:</p> <pre><code>xxd -b file </code></pre> <p>hex:</p> <pre><code>xxd file </code></pre> | 368, 390 | binary, shell | <h1>How to view files in binary from bash?</h1>
<p>I would like to view the contents of a file in the current directory, but in binary from the command line. How can I achieve this?</p>
<p>For example, something like this:</p>
<pre class="lang-none prettyprint-override"><code>$ cat test
Hello, world!
$ binarycat test
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 240 | bash | # How to view files in binary from bash?
I would like to view the contents of a file in the current directory, but in binary from the command line. How can I achieve this?
For example, something like this:
```
$ cat test
Hello, world!
$ binarycat test
01001000 01100101 01101100 01101100 01101111 00101100
00100000 0... | [`xxd`](https://linux.die.net/man/1/xxd) does both binary and hexadecimal.
bin:
```
xxd -b file
```
hex:
```
xxd file
``` |
29244351 | How to sort a file in-place? | 350 | 2015-03-24 22:49:08 | <p>When we use the <code>sort file</code> command,
the file shows its contents in a sorted way. What if I don't want to get any output on stdout, but in the input file instead?</p>
| 218,702 | 4,705,190 | 2023-04-25 02:41:34 | 29,244,408 | 706 | 2015-03-24 22:53:57 | 4,698,204 | 2022-06-06 09:44:06 | https://stackoverflow.com/q/29244351 | https://stackoverflow.com/a/29244408 | <p>You can use the <code>-o</code>, <code>--output=FILE</code> option of sort to indicate the same input and output file:</p>
<pre><code>sort -o file file
</code></pre>
<p>Without repeating the filename (with <a href="https://www.gnu.org/software/bash/manual/html_node/Brace-Expansion.html" rel="noreferrer">bash brace e... | <p>You can use the <code>-o</code>, <code>--output=FILE</code> option of sort to indicate the same input and output file:</p> <pre><code>sort -o file file </code></pre> <p>Without repeating the filename (with <a href="https://www.gnu.org/software/bash/manual/html_node/Brace-Expansion.html" rel="noreferrer">bash brace e... | 34, 58, 387, 390 | bash, linux, shell, unix | <h1>How to sort a file in-place?</h1>
<p>When we use the <code>sort file</code> command,
the file shows its contents in a sorted way. What if I don't want to get any output on stdout, but in the input file instead?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 241 | bash | # How to sort a file in-place?
When we use the `sort file` command,
the file shows its contents in a sorted way. What if I don't want to get any output on stdout, but in the input file instead? | You can use the `-o`, `--output=FILE` option of sort to indicate the same input and output file:
```
sort -o file file
```
Without repeating the filename (with [bash brace expansion](https://www.gnu.org/software/bash/manual/html_node/Brace-Expansion.html))
```
sort -o file{,}
```
⚠️ **Important note:** a common mis... |
45142855 | /bin/sh: apt-get: not found | 283 | 2017-07-17 11:18:39 | <p>I am trying to change a dockerFile to work with aspell. I have a bash script that I want to wrap in a dock</p>
<blockquote>
<p>Step 4: Wrap the script in a Docker container.</p>
<p>The sample SDK we downloaded earlier contains an example of an action wrapped in a Docker container. In particular, the sample SDK inclu... | 455,702 | 7,877,578 | 2024-10-05 08:27:39 | 45,143,116 | 706 | 2017-07-17 11:29:43 | 3,411,861 | 2017-07-17 11:33:41 | https://stackoverflow.com/q/45142855 | https://stackoverflow.com/a/45143116 | <p>The <a href="https://hub.docker.com/r/openwhisk/dockerskeleton/~/dockerfile/" rel="noreferrer">image you're using</a> is <a href="https://alpinelinux.org" rel="noreferrer">Alpine based</a>, so you can't use <code>apt-get</code> because it's Ubuntu's package manager.</p>
<p>To fix this just use: </p>
<p><code>apk u... | <p>The <a href="https://hub.docker.com/r/openwhisk/dockerskeleton/~/dockerfile/" rel="noreferrer">image you're using</a> is <a href="https://alpinelinux.org" rel="noreferrer">Alpine based</a>, so you can't use <code>apt-get</code> because it's Ubuntu's package manager.</p> <p>To fix this just use: </p> <p><code>apk u... | 387, 4905, 90304, 108477 | aspell, bash, docker, dockerfile | <h1>/bin/sh: apt-get: not found</h1>
<p>I am trying to change a dockerFile to work with aspell. I have a bash script that I want to wrap in a dock</p>
<blockquote>
<p>Step 4: Wrap the script in a Docker container.</p>
<p>The sample SDK we downloaded earlier contains an example of an action wrapped in a Docker container... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 242 | bash | # /bin/sh: apt-get: not found
I am trying to change a dockerFile to work with aspell. I have a bash script that I want to wrap in a dock
> Step 4: Wrap the script in a Docker container.
>
> The sample SDK we downloaded earlier contains an example of an action wrapped in a Docker container. In particular, the sample S... | The [image you're using](https://hub.docker.com/r/openwhisk/dockerskeleton/~/dockerfile/) is [Alpine based](https://alpinelinux.org), so you can't use `apt-get` because it's Ubuntu's package manager.
To fix this just use:
`apk update` and `apk add` |
296536 | How to urlencode data for curl command? | 570 | 2008-11-17 19:09:59 | <p>I am trying to write a bash script for testing that takes a parameter and sends it through curl to web site. I need to url encode the value to make sure that special characters are processed properly. What is the best way to do this? </p>
<p>Here is my basic script so far:</p>
<pre><code>#!/bin/bash
host=${1:?'... | 823,331 | 19,130 | 2024-08-07 11:38:35 | 2,027,690 | 700 | 2010-01-08 13:05:40 | 114,168 | 2022-04-19 08:20:09 | https://stackoverflow.com/q/296536 | https://stackoverflow.com/a/2027690 | <p>Use <code>curl --data-urlencode</code>; from <code>man curl</code>:</p>
<blockquote>
<p>This posts data, similar to the other <code>--data</code> options with the exception that this performs URL-encoding. To be CGI-compliant, the <code><data></code> part should begin with a name followed by a separator and a ... | <p>Use <code>curl --data-urlencode</code>; from <code>man curl</code>:</p> <blockquote> <p>This posts data, similar to the other <code>--data</code> options with the exception that this performs URL-encoding. To be CGI-compliant, the <code><data></code> part should begin with a name followed by a separator and a ... | 387, 390, 531, 1554, 8023 | bash, curl, scripting, shell, urlencode | <h1>How to urlencode data for curl command?</h1>
<p>I am trying to write a bash script for testing that takes a parameter and sends it through curl to web site. I need to url encode the value to make sure that special characters are processed properly. What is the best way to do this? </p>
<p>Here is my basic scrip... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 243 | bash | # How to urlencode data for curl command?
I am trying to write a bash script for testing that takes a parameter and sends it through curl to web site. I need to url encode the value to make sure that special characters are processed properly. What is the best way to do this?
Here is my basic script so far:
```
#!/bi... | Use `curl --data-urlencode`; from `man curl`:
> This posts data, similar to the other `--data` options with the exception that this performs URL-encoding. To be CGI-compliant, the `<data>` part should begin with a name followed by a separator and a content specification.
Example usage:
```
curl \
--data-urlencod... |
50861082 | How to print environment variables to the console in PowerShell? | 481 | 2018-06-14 15:29:32 | <p>I'm starting to use PowerShell and am trying to figure out how to <code>echo</code> a system environment variable to the console to read it.</p>
<p>Neither of the below are working. The first just prints <code>%PATH%</code>, and the second prints nothing.</p>
<pre><code>echo %PATH%
echo $PATH
</code></pre>
| 550,616 | 1,103,595 | 2024-07-28 11:03:17 | 50,861,113 | 698 | 2018-06-14 15:31:25 | 712,649 | 2024-07-28 11:03:17 | https://stackoverflow.com/q/50861082 | https://stackoverflow.com/a/50861113 | <p>Prefix the variable name with <code>env</code>:</p>
<pre><code>$env:path
</code></pre>
<p>For example, if you want to print the value of environment value <code>MINISHIFT_USERNAME</code>, then command will be:</p>
<pre><code>$env:MINISHIFT_USERNAME
</code></pre>
<p>In case the environment variable label contains cha... | <p>Prefix the variable name with <code>env</code>:</p> <pre><code>$env:path </code></pre> <p>For example, if you want to print the value of environment value <code>MINISHIFT_USERNAME</code>, then command will be:</p> <pre><code>$env:MINISHIFT_USERNAME </code></pre> <p>In case the environment variable label contains cha... | 526 | powershell | <h1>How to print environment variables to the console in PowerShell?</h1>
<p>I'm starting to use PowerShell and am trying to figure out how to <code>echo</code> a system environment variable to the console to read it.</p>
<p>Neither of the below are working. The first just prints <code>%PATH%</code>, and the second pr... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 244 | bash | # How to print environment variables to the console in PowerShell?
I'm starting to use PowerShell and am trying to figure out how to `echo` a system environment variable to the console to read it.
Neither of the below are working. The first just prints `%PATH%`, and the second prints nothing.
```
echo %PATH%
echo $P... | Prefix the variable name with `env`:
```
$env:path
```
For example, if you want to print the value of environment value `MINISHIFT_USERNAME`, then command will be:
```
$env:MINISHIFT_USERNAME
```
In case the environment variable label contains characters otherwise interpreted as bareword token terminators (like `.`... |
3968103 | How can I format my grep output to show line numbers at the end of the line, and also the hit count? | 445 | 2010-10-19 12:06:02 | <p>I'm using grep to match string in a file. Here is an example file:</p>
<pre><code>example one,
example two null,
example three,
example four null,
</code></pre>
<p><code>grep -i null myfile.txt</code> returns </p>
<pre><code>example two null,
example four null,
</code></pre>
<p>How can I return matched lines tog... | 444,052 | 282,383 | 2019-07-03 14:28:46 | 3,968,142 | 695 | 2010-10-19 12:10:17 | 7,412 | 2016-08-08 18:20:38 | https://stackoverflow.com/q/3968103 | https://stackoverflow.com/a/3968142 | <p><code>-n</code> returns line number.</p>
<p><code>-i</code> is for ignore-case. Only to be used if case matching is not necessary</p>
<pre><code>$ grep -in null myfile.txt
2:example two null,
4:example four null,
</code></pre>
<p>Combine with <code>awk</code> to print out the line number after the match:</p>
<p... | <p><code>-n</code> returns line number.</p> <p><code>-i</code> is for ignore-case. Only to be used if case matching is not necessary</p> <pre><code>$ grep -in null myfile.txt 2:example two null, 4:example four null, </code></pre> <p>Combine with <code>awk</code> to print out the line number after the match:</p> <p... | 34, 58, 387, 1271 | bash, grep, linux, unix | <h1>How can I format my grep output to show line numbers at the end of the line, and also the hit count?</h1>
<p>I'm using grep to match string in a file. Here is an example file:</p>
<pre><code>example one,
example two null,
example three,
example four null,
</code></pre>
<p><code>grep -i null myfile.txt</code> retu... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 245 | bash | # How can I format my grep output to show line numbers at the end of the line, and also the hit count?
I'm using grep to match string in a file. Here is an example file:
```
example one,
example two null,
example three,
example four null,
```
`grep -i null myfile.txt` returns
```
example two null,
example four null... | `-n` returns line number.
`-i` is for ignore-case. Only to be used if case matching is not necessary
```
$ grep -in null myfile.txt
2:example two null,
4:example four null,
```
Combine with `awk` to print out the line number after the match:
```
$ grep -in null myfile.txt | awk -F: '{print $2" - Line number : "$1}... |
12457457 | count number of lines in terminal output | 393 | 2012-09-17 10:31:50 | <p>couldn't find this on SO. I ran the following command in the terminal: </p>
<pre><code>>> grep -Rl "curl" ./
</code></pre>
<p>and this displays the list of files where the keyword curl occurs. I want to count the number of files. First way I can think of, is to count the number of lines in the output that ca... | 420,134 | 799,068 | 2024-08-22 14:27:05 | 12,457,470 | 695 | 2012-09-17 10:32:36 | 140,816 | 2012-09-17 10:32:36 | https://stackoverflow.com/q/12457457 | https://stackoverflow.com/a/12457470 | <p>Pipe the result to <a href="http://en.wikipedia.org/wiki/Wc_%28Unix%29" rel="noreferrer"><code>wc</code></a> using the <code>-l</code> (<em>line count</em>) switch:</p>
<pre><code>grep -Rl "curl" ./ | wc -l
</code></pre>
| <p>Pipe the result to <a href="http://en.wikipedia.org/wiki/Wc_%28Unix%29" rel="noreferrer"><code>wc</code></a> using the <code>-l</code> (<em>line count</em>) switch:</p> <pre><code>grep -Rl "curl" ./ | wc -l </code></pre> | 387, 391 | bash, terminal | <h1>count number of lines in terminal output</h1>
<p>couldn't find this on SO. I ran the following command in the terminal: </p>
<pre><code>>> grep -Rl "curl" ./
</code></pre>
<p>and this displays the list of files where the keyword curl occurs. I want to count the number of files. First way I can think of, is ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 246 | bash | # count number of lines in terminal output
couldn't find this on SO. I ran the following command in the terminal:
```
>> grep -Rl "curl" ./
```
and this displays the list of files where the keyword curl occurs. I want to count the number of files. First way I can think of, is to count the number of lines in the outp... | Pipe the result to [`wc`](http://en.wikipedia.org/wiki/Wc_%28Unix%29) using the `-l` (*line count*) switch:
```
grep -Rl "curl" ./ | wc -l
``` |
9381463 | How to create a file in Linux from terminal window? | 553 | 2012-02-21 16:42:47 | <p>What's the easiest way to create a file in Linux terminal?</p>
| 2,216,433 | 791,406 | 2019-04-15 21:16:46 | 9,381,492 | 694 | 2012-02-21 16:44:48 | 1,100,552 | 2013-07-30 11:49:39 | https://stackoverflow.com/q/9381463 | https://stackoverflow.com/a/9381492 | <p>Depending on what you want the file to contain:</p>
<ul>
<li><code>touch /path/to/file</code> for an empty file</li>
<li><p><code>somecommand > /path/to/file</code> for a file containing the output of some command.</p>
<pre><code> eg: grep --help > randomtext.txt
echo "This is some text" > randomte... | <p>Depending on what you want the file to contain:</p> <ul> <li><code>touch /path/to/file</code> for an empty file</li> <li><p><code>somecommand > /path/to/file</code> for a file containing the output of some command.</p> <pre><code> eg: grep --help > randomtext.txt echo "This is some text" > randomte... | 58, 387, 5310, 11225 | bash, command-line-interface, file, linux | <h1>How to create a file in Linux from terminal window?</h1>
<p>What's the easiest way to create a file in Linux terminal?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 247 | bash | # How to create a file in Linux from terminal window?
What's the easiest way to create a file in Linux terminal? | Depending on what you want the file to contain:
- `touch /path/to/file` for an empty file
- `somecommand > /path/to/file` for a file containing the output of some command.
```
eg: grep --help > randomtext.txt
echo "This is some text" > randomtext.txt
```
- `nano /path/to/file` or `vi /path/to/file` (o... |
617182 | How can I suppress all output from a command using Bash? | 417 | 2009-03-05 23:38:25 | <p>I have a Bash script that runs a program with parameters. That program outputs some status (doing this, doing that...). There isn't any option for this program to be quiet. How can I prevent the script from displaying anything?</p>
<p>I am looking for something like Windows' <a href="https://ss64.com/nt/echo.html"... | 510,578 | 74,480 | 2024-08-13 12:57:53 | 617,184 | 690 | 2009-03-05 23:39:17 | 46,354 | 2020-06-04 13:35:47 | https://stackoverflow.com/q/617182 | https://stackoverflow.com/a/617184 | <p>The following sends standard output to the null device (bit bucket).</p>
<pre><code>scriptname >/dev/null
</code></pre>
<p>And if you also want error messages to be sent there, use one of (the first may not work in all shells):</p>
<pre><code>scriptname &>/dev/null
scriptname >/dev/null 2>&1
s... | <p>The following sends standard output to the null device (bit bucket).</p> <pre><code>scriptname >/dev/null </code></pre> <p>And if you also want error messages to be sent there, use one of (the first may not work in all shells):</p> <pre><code>scriptname &>/dev/null scriptname >/dev/null 2>&1 s... | 387, 390, 531, 13824 | bash, echo, scripting, shell | <h1>How can I suppress all output from a command using Bash?</h1>
<p>I have a Bash script that runs a program with parameters. That program outputs some status (doing this, doing that...). There isn't any option for this program to be quiet. How can I prevent the script from displaying anything?</p>
<p>I am looking f... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 248 | bash | # How can I suppress all output from a command using Bash?
I have a Bash script that runs a program with parameters. That program outputs some status (doing this, doing that...). There isn't any option for this program to be quiet. How can I prevent the script from displaying anything?
I am looking for something like... | The following sends standard output to the null device (bit bucket).
```
scriptname >/dev/null
```
And if you also want error messages to be sent there, use one of (the first may not work in all shells):
```
scriptname &>/dev/null
scriptname >/dev/null 2>&1
scriptname >/dev/null 2>/dev/null
```
And, if you want to ... |
7114990 | Pseudo-terminal will not be allocated because stdin is not a terminal | 512 | 2011-08-18 22:38:40 | <p>I am trying to write a shell script that creates some directories on a remote server and then uses scp to copy files from my local machine onto the remote. Here's what I have so far:</p>
<pre><code>ssh -t user@server<<EOT
DEP_ROOT='/home/matthewr/releases'
datestamp=$(date +%Y%m%d%H%M%S)
REL_DIR=$DEP_ROOT"/"$... | 779,453 | 818,091 | 2022-11-27 20:30:14 | 7,122,115 | 689 | 2011-08-19 13:14:23 | 902,495 | 2017-12-02 14:30:41 | https://stackoverflow.com/q/7114990 | https://stackoverflow.com/a/7122115 | <p>Try <code>ssh -t -t</code>(or <code>ssh -tt</code> for short) to force pseudo-tty allocation even if stdin isn't a terminal.</p>
<p>See also: <a href="https://stackoverflow.com/questions/7085429/terminating-ssh-session-executed-by-bash-script">Terminating SSH session executed by bash script</a></p>
<p>From ssh man... | <p>Try <code>ssh -t -t</code>(or <code>ssh -tt</code> for short) to force pseudo-tty allocation even if stdin isn't a terminal.</p> <p>See also: <a href="https://stackoverflow.com/questions/7085429/terminating-ssh-session-executed-by-bash-script">Terminating SSH session executed by bash script</a></p> <p>From ssh man... | 58, 386, 387, 390 | bash, linux, shell, ssh | <h1>Pseudo-terminal will not be allocated because stdin is not a terminal</h1>
<p>I am trying to write a shell script that creates some directories on a remote server and then uses scp to copy files from my local machine onto the remote. Here's what I have so far:</p>
<pre><code>ssh -t user@server<<EOT
DEP_ROOT=... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 249 | bash | # Pseudo-terminal will not be allocated because stdin is not a terminal
I am trying to write a shell script that creates some directories on a remote server and then uses scp to copy files from my local machine onto the remote. Here's what I have so far:
```
ssh -t user@server<<EOT
DEP_ROOT='/home/matthewr/releases'
... | Try `ssh -t -t`(or `ssh -tt` for short) to force pseudo-tty allocation even if stdin isn't a terminal.
See also: [Terminating SSH session executed by bash script](https://stackoverflow.com/questions/7085429/terminating-ssh-session-executed-by-bash-script)
From ssh manpage:
```
-T Disable pseudo-tty allocation.
... |
10341271 | Switching from zsh to bash on OS X, and back again? | 359 | 2012-04-26 20:52:23 | <p>I'm learning to develop in Rails, and have discovered the power of <code>zsh</code>. However, for some of my other tasks, I wish to use normal <code>bash</code>.</p>
<p>Although they are the same, I just feel comfortable with the layout of <code>bash</code> in some situations.</p>
<p>How do I switch back and forth, ... | 509,519 | 1,359,708 | 2023-09-09 17:05:35 | 10,341,338 | 687 | 2012-04-26 20:58:41 | 147,356 | 2012-04-26 20:58:41 | https://stackoverflow.com/q/10341271 | https://stackoverflow.com/a/10341338 | <p>You can just use <code>exec</code> to replace your current shell with a new shell:</p>
<p>Switch to <code>bash</code>:</p>
<pre><code>exec bash
</code></pre>
<p>Switch to <code>zsh</code>:</p>
<pre><code>exec zsh
</code></pre>
<p>This won't affect new terminal windows or anything, but it's convenient.</p>
| <p>You can just use <code>exec</code> to replace your current shell with a new shell:</p> <p>Switch to <code>bash</code>:</p> <pre><code>exec bash </code></pre> <p>Switch to <code>zsh</code>:</p> <pre><code>exec zsh </code></pre> <p>This won't affect new terminal windows or anything, but it's convenient.</p> | 387, 391, 3791 | bash, terminal, zsh | <h1>Switching from zsh to bash on OS X, and back again?</h1>
<p>I'm learning to develop in Rails, and have discovered the power of <code>zsh</code>. However, for some of my other tasks, I wish to use normal <code>bash</code>.</p>
<p>Although they are the same, I just feel comfortable with the layout of <code>bash</code... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 250 | bash | # Switching from zsh to bash on OS X, and back again?
I'm learning to develop in Rails, and have discovered the power of `zsh`. However, for some of my other tasks, I wish to use normal `bash`.
Although they are the same, I just feel comfortable with the layout of `bash` in some situations.
How do I switch back and ... | You can just use `exec` to replace your current shell with a new shell:
Switch to `bash`:
```
exec bash
```
Switch to `zsh`:
```
exec zsh
```
This won't affect new terminal windows or anything, but it's convenient. |
19075671 | How do I use shell variables in an awk script? | 416 | 2013-09-29 07:45:03 | <p>I found some ways to pass external shell variables to an <code>awk</code> script, but I'm confused about <code>'</code> and <code>"</code>.</p>
<p>First, I tried with a shell script:</p>
<pre><code>$ v=123test
$ echo $v
123test
$ echo "$v"
123test
</code></pre>
<p>Then tried awk:</p>
<pre><code>$ awk 'BEGIN{prin... | 746,867 | 2,266,338 | 2024-06-07 07:37:51 | 19,075,707 | 685 | 2013-09-29 07:51:52 | 2,341,847 | 2024-06-07 07:37:51 | https://stackoverflow.com/q/19075671 | https://stackoverflow.com/a/19075707 | <blockquote>
<p>#Getting shell variables into <code>awk</code>
may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5</p>
</blockquote>
<hr />
<h2>Using ... | <blockquote> <p>#Getting shell variables into <code>awk</code> may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5</p> </blockquote> <hr /> <h2>Using ... | 387, 390, 990 | awk, bash, shell | <h1>How do I use shell variables in an awk script?</h1>
<p>I found some ways to pass external shell variables to an <code>awk</code> script, but I'm confused about <code>'</code> and <code>"</code>.</p>
<p>First, I tried with a shell script:</p>
<pre><code>$ v=123test
$ echo $v
123test
$ echo "$v"
123test
</code></pr... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 251 | bash | # How do I use shell variables in an awk script?
I found some ways to pass external shell variables to an `awk` script, but I'm confused about `'` and `"`.
First, I tried with a shell script:
```
$ v=123test
$ echo $v
123test
$ echo "$v"
123test
```
Then tried awk:
```
$ awk 'BEGIN{print "'$v'"}'
$ 123test
$ awk '... | > #Getting shell variables into `awk`
> may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5
---
## Using `-v` (The best way, most portable)
Use the ... |
786376 | How do I run a program with a different working directory from current, from Linux shell? | 433 | 2009-04-24 15:36:23 | <p>Using a <strong>Linux shell</strong>, how do I start a program with a different working directory from the current working directory?</p>
<p>For example, I have a binary file <code>helloworld</code> that creates the file <code>hello-world.txt</code> in the <strong>current directory</strong>.
<br><br>
This file is ... | 344,355 | 18,775 | 2024-09-04 17:11:45 | 786,419 | 682 | 2009-04-24 15:46:04 | 4,918 | 2015-05-02 23:31:27 | https://stackoverflow.com/q/786376 | https://stackoverflow.com/a/786419 | <p>Call the program like this:</p>
<pre><code>(cd /c; /a/helloworld)
</code></pre>
<p>The parentheses cause a sub-shell to be spawned. This sub-shell then changes its working directory to <code>/c</code>, then executes <code>helloworld</code> from <code>/a</code>. After the program exits, the sub-shell terminates, re... | <p>Call the program like this:</p> <pre><code>(cd /c; /a/helloworld) </code></pre> <p>The parentheses cause a sub-shell to be spawned. This sub-shell then changes its working directory to <code>/c</code>, then executes <code>helloworld</code> from <code>/a</code>. After the program exits, the sub-shell terminates, re... | 58, 390, 421 | environment, linux, shell | <h1>How do I run a program with a different working directory from current, from Linux shell?</h1>
<p>Using a <strong>Linux shell</strong>, how do I start a program with a different working directory from the current working directory?</p>
<p>For example, I have a binary file <code>helloworld</code> that creates the f... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 252 | bash | # How do I run a program with a different working directory from current, from Linux shell?
Using a **Linux shell**, how do I start a program with a different working directory from the current working directory?
For example, I have a binary file `helloworld` that creates the file `hello-world.txt` in the **current d... | Call the program like this:
```
(cd /c; /a/helloworld)
```
The parentheses cause a sub-shell to be spawned. This sub-shell then changes its working directory to `/c`, then executes `helloworld` from `/a`. After the program exits, the sub-shell terminates, returning you to your prompt of the parent shell, in the direc... |
11193466 | "echo -n" prints "-n" | 638 | 2012-06-25 16:38:14 | <p>I have a problem with <code>echo</code> in my script:</p>
<pre><code>echo -n "Some string..."
</code></pre>
<p>prints</p>
<pre class="lang-none prettyprint-override"><code>-n Some string...
</code></pre>
<p>and moves to the next line. In the console it's working correcly without newline:</p>
<pre class="lang-no... | 708,612 | 1,202,769 | 2024-03-13 02:08:19 | 11,193,533 | 679 | 2012-06-25 16:42:33 | 827,263 | 2024-03-13 02:08:19 | https://stackoverflow.com/q/11193466 | https://stackoverflow.com/a/11193533 | <p>There are multiple versions of the <code>echo</code> command, with different behaviors. It's often built into the shell. If it isn't, <code>echo</code> will typically invoke <code>/bin/echo</code> or <code>/usr/bin/echo</code>, which itself can be from any of a number of implementations.</p>
<p>Apparently the shell ... | <p>There are multiple versions of the <code>echo</code> command, with different behaviors. It's often built into the shell. If it isn't, <code>echo</code> will typically invoke <code>/bin/echo</code> or <code>/usr/bin/echo</code>, which itself can be from any of a number of implementations.</p> <p>Apparently the shell ... | 10327 | sh | <h1>"echo -n" prints "-n"</h1>
<p>I have a problem with <code>echo</code> in my script:</p>
<pre><code>echo -n "Some string..."
</code></pre>
<p>prints</p>
<pre class="lang-none prettyprint-override"><code>-n Some string...
</code></pre>
<p>and moves to the next line. In the console it's working correcly without ne... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 253 | bash | # "echo -n" prints "-n"
I have a problem with `echo` in my script:
```
echo -n "Some string..."
```
prints
```
-n Some string...
```
and moves to the next line. In the console it's working correcly without newline:
```
Some string...
``` | There are multiple versions of the `echo` command, with different behaviors. It's often built into the shell. If it isn't, `echo` will typically invoke `/bin/echo` or `/usr/bin/echo`, which itself can be from any of a number of implementations.
Apparently the shell used for your script uses a version that doesn't reco... |
15691942 | Print array elements on separate lines in Bash? | 371 | 2013-03-28 20:53:47 | <p>How do I print the array element of a Bash array on separate lines? This one works, but surely there is a better way:</p>
<pre><code>$ my_array=(one two three)
$ for i in ${my_array[@]}; do echo $i; done
one
two
three
</code></pre>
<p>Tried this one but it did not work:</p>
<pre><code>$ IFS=$'\n' echo ${my_array[... | 544,889 | 155,425 | 2023-08-02 05:51:29 | 15,692,004 | 679 | 2013-03-28 20:57:30 | 465,183 | 2023-02-20 17:32:28 | https://stackoverflow.com/q/15691942 | https://stackoverflow.com/a/15692004 | <p>Try doing this :</p>
<pre><code>$ printf '%s\n' "${my_array[@]}"
</code></pre>
<p>The difference between <code>$@</code> and <code>$*</code>:</p>
<ul>
<li><p>Unquoted, the results are unspecified. In Bash, both expand to separate args
and then wordsplit and globbed.</p>
</li>
<li><p>Quoted, <code>"$@&... | <p>Try doing this :</p> <pre><code>$ printf '%s\n' "${my_array[@]}" </code></pre> <p>The difference between <code>$@</code> and <code>$*</code>:</p> <ul> <li><p>Unquoted, the results are unspecified. In Bash, both expand to separate args and then wordsplit and globbed.</p> </li> <li><p>Quoted, <code>"$@&... | 114, 387 | arrays, bash | <h1>Print array elements on separate lines in Bash?</h1>
<p>How do I print the array element of a Bash array on separate lines? This one works, but surely there is a better way:</p>
<pre><code>$ my_array=(one two three)
$ for i in ${my_array[@]}; do echo $i; done
one
two
three
</code></pre>
<p>Tried this one but it d... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 254 | bash | # Print array elements on separate lines in Bash?
How do I print the array element of a Bash array on separate lines? This one works, but surely there is a better way:
```
$ my_array=(one two three)
$ for i in ${my_array[@]}; do echo $i; done
one
two
three
```
Tried this one but it did not work:
```
$ IFS=$'\n' ech... | Try doing this :
```
$ printf '%s\n' "${my_array[@]}"
```
The difference between `$@` and `$*`:
- Unquoted, the results are unspecified. In Bash, both expand to separate args
and then wordsplit and globbed.
- Quoted, `"$@"` expands each element as a separate argument, while `"$*"`
expands to the args merged into... |
10552711 | How to make "if not true condition"? | 489 | 2012-05-11 13:51:37 | <p>I would like to have the <code>echo</code> command executed when <code>cat /etc/passwd | grep "sysa"</code> is not true.</p>
<p>What am I doing wrong?</p>
<pre><code>if ! [ $(cat /etc/passwd | grep "sysa") ]; then
echo "ERROR - The user sysa could not be looked up"
exit 2
fi
</code></pre>
| 949,653 | 256,439 | 2025-08-22 04:55:33 | 10,552,775 | 675 | 2012-05-11 13:54:59 | 620,097 | 2025-08-22 04:55:33 | https://stackoverflow.com/q/10552711 | https://stackoverflow.com/a/10552775 | <p>Try</p>
<pre><code>if ! grep -q sysa /etc/passwd ; then
</code></pre>
<p><code>grep</code> returns <code>true</code> if it finds the search target, and <code>false</code> if it doesn't.</p>
<p>So NOT false (<code>! false</code>) == <code>true</code>.</p>
<p><code>if</code> evaluation in shells are designed to be ver... | <p>Try</p> <pre><code>if ! grep -q sysa /etc/passwd ; then </code></pre> <p><code>grep</code> returns <code>true</code> if it finds the search target, and <code>false</code> if it doesn't.</p> <p>So NOT false (<code>! false</code>) == <code>true</code>.</p> <p><code>if</code> evaluation in shells are designed to be ver... | 367, 387, 2773, 15128 | bash, boolean-expression, if-statement, syntax | <h1>How to make "if not true condition"?</h1>
<p>I would like to have the <code>echo</code> command executed when <code>cat /etc/passwd | grep "sysa"</code> is not true.</p>
<p>What am I doing wrong?</p>
<pre><code>if ! [ $(cat /etc/passwd | grep "sysa") ]; then
echo "ERROR - The user sysa could not be looked... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 255 | bash | # How to make "if not true condition"?
I would like to have the `echo` command executed when `cat /etc/passwd | grep "sysa"` is not true.
What am I doing wrong?
```
if ! [ $(cat /etc/passwd | grep "sysa") ]; then
echo "ERROR - The user sysa could not be looked up"
exit 2
fi
``` | Try
```
if ! grep -q sysa /etc/passwd ; then
```
`grep` returns `true` if it finds the search target, and `false` if it doesn't.
So NOT false (`! false`) == `true`.
`if` evaluation in shells are designed to be very flexible, and many times doesn't require chains of commands (as you have written).
Also, looking at ... |
11245144 | Replace whole line containing a string using Sed | 470 | 2012-06-28 12:55:26 | <p>I have a text file which has a particular line something like</p>
<pre><code>sometext sometext sometext TEXT_TO_BE_REPLACED sometext sometext sometext
</code></pre>
<p>I need to replace the whole line above with </p>
<pre><code>This line is removed by the admin.
</code></pre>
<p>The search keyword is <code>TEXT_... | 804,847 | 1,254,009 | 2025-06-04 13:22:54 | 11,245,501 | 674 | 2012-06-28 13:15:02 | 1,301,972 | 2018-11-30 00:25:02 | https://stackoverflow.com/q/11245144 | https://stackoverflow.com/a/11245501 | <p>You can use the <em>change</em> command to replace the entire line, and the <code>-i</code> flag to make the changes in-place. For example, using GNU sed:</p>
<pre><code>sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo
</code></pre>
| <p>You can use the <em>change</em> command to replace the entire line, and the <code>-i</code> flag to make the changes in-place. For example, using GNU sed:</p> <pre><code>sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo </code></pre> | 139, 390, 5282 | sed, shell, string | <h1>Replace whole line containing a string using Sed</h1>
<p>I have a text file which has a particular line something like</p>
<pre><code>sometext sometext sometext TEXT_TO_BE_REPLACED sometext sometext sometext
</code></pre>
<p>I need to replace the whole line above with </p>
<pre><code>This line is removed by the ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 256 | bash | # Replace whole line containing a string using Sed
I have a text file which has a particular line something like
```
sometext sometext sometext TEXT_TO_BE_REPLACED sometext sometext sometext
```
I need to replace the whole line above with
```
This line is removed by the admin.
```
The search keyword is `TEXT_TO_BE... | You can use the *change* command to replace the entire line, and the `-i` flag to make the changes in-place. For example, using GNU sed:
```
sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo
``` |
7875540 | How to write multiple line string using Bash with variables? | 348 | 2011-10-24 12:23:51 | <p>How can I write multi-lines in a file called <code>myconfig.conf</code> using BASH?</p>
<pre><code>#!/bin/bash
kernel="2.6.39";
distro="xyz";
echo <<< EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4
line ...
EOL >> /etc/myconfig.conf;
cat /etc/myconfig.conf;
</code></pre>
| 371,266 | null | 2023-07-10 14:08:00 | 7,875,614 | 674 | 2011-10-24 12:29:40 | 944,391 | 2019-09-08 11:13:47 | https://stackoverflow.com/q/7875540 | https://stackoverflow.com/a/7875614 | <p>The syntax (<code><<<</code>) and the command used (<code>echo</code>) is wrong.</p>
<p>Correct would be:</p>
<pre><code>#!/bin/bash
kernel="2.6.39"
distro="xyz"
cat >/etc/myconfig.conf <<EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4 line
...
EOL
cat /etc/myconfig.conf
</code></pre>
... | <p>The syntax (<code><<<</code>) and the command used (<code>echo</code>) is wrong.</p> <p>Correct would be:</p> <pre><code>#!/bin/bash kernel="2.6.39" distro="xyz" cat >/etc/myconfig.conf <<EOL line 1, ${kernel} line 2, line 3, ${distro} line 4 line ... EOL cat /etc/myconfig.conf </code></pre> ... | 58, 387, 29051 | bash, bash4, linux | <h1>How to write multiple line string using Bash with variables?</h1>
<p>How can I write multi-lines in a file called <code>myconfig.conf</code> using BASH?</p>
<pre><code>#!/bin/bash
kernel="2.6.39";
distro="xyz";
echo <<< EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4
line ...
EOL >> /etc/myc... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 257 | bash | # How to write multiple line string using Bash with variables?
How can I write multi-lines in a file called `myconfig.conf` using BASH?
```
#!/bin/bash
kernel="2.6.39";
distro="xyz";
echo <<< EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4
line ...
EOL >> /etc/myconfig.conf;
cat /etc/myconfig.conf;
``` | The syntax (`<<<`) and the command used (`echo`) is wrong.
Correct would be:
```
#!/bin/bash
kernel="2.6.39"
distro="xyz"
cat >/etc/myconfig.conf <<EOL
line 1, ${kernel}
line 2,
line 3, ${distro}
line 4 line
...
EOL
cat /etc/myconfig.conf
```
This construction is referred to as a [Here Document](https://en.wikip... |
4426442 | Unix tail equivalent command in Windows Powershell | 507 | 2010-12-13 06:55:28 | <p>I have to look at the last few lines of a large file (typical size is 500MB-2GB). I am looking for an equivalent of the Unix command <code>tail</code> for Windows Powershell. A few alternatives available are,</p>
<p><a href="http://tailforwin32.sourceforge.net/" rel="noreferrer">http://tailforwin32.sourceforge.net/<... | 545,213 | 520,382 | 2024-08-23 01:35:47 | 4,427,285 | 673 | 2010-12-13 09:15:34 | 236,131 | 2017-01-05 15:05:55 | https://stackoverflow.com/q/4426442 | https://stackoverflow.com/a/4427285 | <p>Use the <code>-wait</code> parameter with Get-Content, which displays lines as they are added to the file. This feature was present in PowerShell v1, but for some reason not documented well in v2.</p>
<p>Here is an example</p>
<pre><code>Get-Content -Path "C:\scripts\test.txt" -Wait
</code></pre>
<p>Once you run ... | <p>Use the <code>-wait</code> parameter with Get-Content, which displays lines as they are added to the file. This feature was present in PowerShell v1, but for some reason not documented well in v2.</p> <p>Here is an example</p> <pre><code>Get-Content -Path "C:\scripts\test.txt" -Wait </code></pre> <p>Once you run ... | 34, 64, 526, 7896 | powershell, tail, unix, windows | <h1>Unix tail equivalent command in Windows Powershell</h1>
<p>I have to look at the last few lines of a large file (typical size is 500MB-2GB). I am looking for an equivalent of the Unix command <code>tail</code> for Windows Powershell. A few alternatives available are,</p>
<p><a href="http://tailforwin32.sourceforge.... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 258 | bash | # Unix tail equivalent command in Windows Powershell
I have to look at the last few lines of a large file (typical size is 500MB-2GB). I am looking for an equivalent of the Unix command `tail` for Windows Powershell. A few alternatives available are,
<http://tailforwin32.sourceforge.net/>
and
```
Get-Content [filen... | Use the `-wait` parameter with Get-Content, which displays lines as they are added to the file. This feature was present in PowerShell v1, but for some reason not documented well in v2.
Here is an example
```
Get-Content -Path "C:\scripts\test.txt" -Wait
```
Once you run this, update and save the file and you will s... |
1529946 | Linux: copy and create destination dir if it does not exist | 661 | 2009-10-07 06:55:27 | <p>I want a command (or probably an option to cp) that creates the destination directory if it does not exist.</p>
<p>Example:</p>
<pre><code>cp -? file /path/to/copy/file/to/is/very/deep/there
</code></pre>
| 693,773 | 63,051 | 2025-01-23 13:34:12 | 1,529,965 | 666 | 2009-10-07 06:58:54 | 95,382 | 2018-09-10 09:33:58 | https://stackoverflow.com/q/1529946 | https://stackoverflow.com/a/1529965 | <pre><code>mkdir -p "$d" && cp file "$d"
</code></pre>
<p>(there's no such option for <code>cp</code>).</p>
| <pre><code>mkdir -p "$d" && cp file "$d" </code></pre> <p>(there's no such option for <code>cp</code>).</p> | 34, 58, 387, 390, 25299 | bash, cp, linux, shell, unix | <h1>Linux: copy and create destination dir if it does not exist</h1>
<p>I want a command (or probably an option to cp) that creates the destination directory if it does not exist.</p>
<p>Example:</p>
<pre><code>cp -? file /path/to/copy/file/to/is/very/deep/there
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 259 | bash | # Linux: copy and create destination dir if it does not exist
I want a command (or probably an option to cp) that creates the destination directory if it does not exist.
Example:
```
cp -? file /path/to/copy/file/to/is/very/deep/there
``` | ```
mkdir -p "$d" && cp file "$d"
```
(there's no such option for `cp`). |
16085958 | Find the files that have been changed in last 24 hours | 372 | 2013-04-18 14:38:46 | <p>E.g., a MySQL server is running on my Ubuntu machine. Some data has been changed during the last 24 hours.</p>
<p>What (Linux) scripts can find the files that have been changed during the last 24 hours?</p>
<p>Please list the file names, file sizes, and modified time.</p>
| 581,231 | 1,258,409 | 2024-06-20 22:56:16 | 16,086,041 | 665 | 2013-04-18 14:42:08 | 970,616 | 2016-12-08 18:27:03 | https://stackoverflow.com/q/16085958 | https://stackoverflow.com/a/16086041 | <p>To find all files modified in the last 24 hours (last full day) in a particular specific directory and its sub-directories:</p>
<pre><code>find /directory_path -mtime -1 -ls
</code></pre>
<p>Should be to your liking</p>
<p>The <code>-</code> before <code>1</code> is important - it means anything changed one day o... | <p>To find all files modified in the last 24 hours (last full day) in a particular specific directory and its sub-directories:</p> <pre><code>find /directory_path -mtime -1 -ls </code></pre> <p>Should be to your liking</p> <p>The <code>-</code> before <code>1</code> is important - it means anything changed one day o... | 58, 387, 10193 | bash, find, linux | <h1>Find the files that have been changed in last 24 hours</h1>
<p>E.g., a MySQL server is running on my Ubuntu machine. Some data has been changed during the last 24 hours.</p>
<p>What (Linux) scripts can find the files that have been changed during the last 24 hours?</p>
<p>Please list the file names, file sizes, a... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 260 | bash | # Find the files that have been changed in last 24 hours
E.g., a MySQL server is running on my Ubuntu machine. Some data has been changed during the last 24 hours.
What (Linux) scripts can find the files that have been changed during the last 24 hours?
Please list the file names, file sizes, and modified time. | To find all files modified in the last 24 hours (last full day) in a particular specific directory and its sub-directories:
```
find /directory_path -mtime -1 -ls
```
Should be to your liking
The `-` before `1` is important - it means anything changed one day or less ago.
A `+` before `1` would instead mean anything... |
37458287 | How to run a cron job inside a docker container? | 570 | 2016-05-26 10:32:53 | <p>I am trying to run a cronjob inside a docker container that invokes a shell script.</p>
<p>How can I do this?</p>
| 844,130 | 6,268,839 | 2026-01-02 18:30:59 | 37,458,519 | 660 | 2016-05-26 10:42:39 | 6,309 | 2026-01-02 18:30:59 | https://stackoverflow.com/q/37458287 | https://stackoverflow.com/a/37458519 | <p>You can copy your <code>crontab</code> into an image, in order for the container launched from said image to run the job.</p>
<hr />
<p><strong>Important</strong>: as noted in <a href="https://github.com/Ekito/docker-cron/issues/3" rel="nofollow noreferrer">docker-cron issue 3</a>: use <a href="https://stackoverflow... | <p>You can copy your <code>crontab</code> into an image, in order for the container launched from said image to run the job.</p> <hr /> <p><strong>Important</strong>: as noted in <a href="https://github.com/Ekito/docker-cron/issues/3" rel="nofollow noreferrer">docker-cron issue 3</a>: use <a href="https://stackoverflow... | 601, 1364, 10327, 90304 | containers, cron, docker, sh | <h1>How to run a cron job inside a docker container?</h1>
<p>I am trying to run a cronjob inside a docker container that invokes a shell script.</p>
<p>How can I do this?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 261 | bash | # How to run a cron job inside a docker container?
I am trying to run a cronjob inside a docker container that invokes a shell script.
How can I do this? | You can copy your `crontab` into an image, in order for the container launched from said image to run the job.
---
**Important**: as noted in [docker-cron issue 3](https://github.com/Ekito/docker-cron/issues/3): use [LF, not CRLF](https://stackoverflow.com/q/1552749/6309) for your `cron` file.
---
See "[Run a cron ... |
3886295 | How do I list one filename per output line in Linux? | 362 | 2010-10-07 22:21:11 | <p>I'm using <code>ls -a</code> command to get the file names in a directory, but the output is in a single line. </p>
<p>Like this:</p>
<pre><code>. .. .bash_history .ssh updater_error_log.txt
</code></pre>
<p>I need a built-in alternative to get filenames, each on a new line, like this:</p>
<pre><code>.
.. ... | 258,336 | 170,005 | 2022-07-01 18:21:03 | 3,886,328 | 660 | 2010-10-07 22:25:25 | 11,296 | 2018-12-29 02:57:02 | https://stackoverflow.com/q/3886295 | https://stackoverflow.com/a/3886328 |
<p>Use the <code>-1</code> option (note this is a "one" digit, not a lowercase letter "L"), like this: </p>
<pre class="lang-none prettyprint-override"><code>ls -1a
</code></pre>
<hr>
<p>First, though, make sure your <code>ls</code> supports <code>-1</code>. GNU coreutils (installed on standard Linux systems) and ... | <p>Use the <code>-1</code> option (note this is a "one" digit, not a lowercase letter "L"), like this: </p> <pre class="lang-none prettyprint-override"><code>ls -1a </code></pre> <hr> <p>First, though, make sure your <code>ls</code> supports <code>-1</code>. GNU coreutils (installed on standard Linux systems) and ... | 58, 390, 3589 | linux, ls, shell | <h1>How do I list one filename per output line in Linux?</h1>
<p>I'm using <code>ls -a</code> command to get the file names in a directory, but the output is in a single line. </p>
<p>Like this:</p>
<pre><code>. .. .bash_history .ssh updater_error_log.txt
</code></pre>
<p>I need a built-in alternative to get fil... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 262 | bash | # How do I list one filename per output line in Linux?
I'm using `ls -a` command to get the file names in a directory, but the output is in a single line.
Like this:
```
. .. .bash_history .ssh updater_error_log.txt
```
I need a built-in alternative to get filenames, each on a new line, like this:
```
.
.. ... | Use the `-1` option (note this is a "one" digit, not a lowercase letter "L"), like this:
```
ls -1a
```
---
First, though, make sure your `ls` supports `-1`. GNU coreutils (installed on standard Linux systems) and Solaris do; but if in doubt, use `man ls` or `ls --help` or check the documentation. E.g.:
```
$ man l... |
26598738 | How to create User/Database in script for Docker Postgres | 399 | 2014-10-27 23:47:58 | <p>I have been trying to set up a container for a development postgres instance by creating a custom user & database. I am using the <a href="https://registry.hub.docker.com/_/postgres/" rel="noreferrer">official postgres docker image</a>. In the documentation it instructs you to insert a bash script inside of the ... | 601,418 | 2,308,178 | 2023-11-15 16:54:12 | 26,599,273 | 654 | 2014-10-28 00:58:38 | 107,049 | 2018-06-26 14:22:30 | https://stackoverflow.com/q/26598738 | https://stackoverflow.com/a/26599273 | <h2>EDIT - since Jul 23, 2015</h2>
<p>The <a href="https://hub.docker.com/_/postgres/" rel="noreferrer">official postgres docker image</a> will run <code>.sql</code> scripts found in the <code>/docker-entrypoint-initdb.d/</code> folder. </p>
<p>So all you need is to create the following sql script: </p>
<p><em>init.... | <h2>EDIT - since Jul 23, 2015</h2> <p>The <a href="https://hub.docker.com/_/postgres/" rel="noreferrer">official postgres docker image</a> will run <code>.sql</code> scripts found in the <code>/docker-entrypoint-initdb.d/</code> folder. </p> <p>So all you need is to create the following sql script: </p> <p><em>init.... | 256, 387, 90304, 106339 | bash, docker, dockerhub, postgresql | <h1>How to create User/Database in script for Docker Postgres</h1>
<p>I have been trying to set up a container for a development postgres instance by creating a custom user & database. I am using the <a href="https://registry.hub.docker.com/_/postgres/" rel="noreferrer">official postgres docker image</a>. In the do... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 263 | bash | # How to create User/Database in script for Docker Postgres
I have been trying to set up a container for a development postgres instance by creating a custom user & database. I am using the [official postgres docker image](https://registry.hub.docker.com/_/postgres/). In the documentation it instructs you to insert a ... | ## EDIT - since Jul 23, 2015
The [official postgres docker image](https://hub.docker.com/_/postgres/) will run `.sql` scripts found in the `/docker-entrypoint-initdb.d/` folder.
So all you need is to create the following sql script:
*init.sql*
```
CREATE USER docker;
CREATE DATABASE docker;
GRANT ALL PRIVILEGES ON ... |
1133698 | Using find to locate files that match one of multiple patterns | 459 | 2009-07-15 20:12:21 | <p>I was trying to get a list of all python and html files in a directory with the command <code>find Documents -name "*.{py,html}"</code>.</p>
<p>Then along came the man page:</p>
<blockquote>
<p>Braces within the pattern (‘{}’) are not considered to be special (that is, find . -name 'foo{1,2}' matches a file name... | 535,661 | 120,999 | 2020-12-30 11:42:34 | 1,133,720 | 652 | 2009-07-15 20:16:00 | 21,886 | 2020-04-23 15:52:07 | https://stackoverflow.com/q/1133698 | https://stackoverflow.com/a/1133720 | <p>Use <code>-o</code>, which means "or":</p>
<pre><code>find Documents \( -name "*.py" -o -name "*.html" \)
</code></pre>
<hr>
<p>You'd need to build that command line programmatically, which isn't that easy.</p>
<p>Are you using bash (or Cygwin on Windows)? If you are, you should be able to do this:</p>
<pre><c... | <p>Use <code>-o</code>, which means "or":</p> <pre><code>find Documents \( -name "*.py" -o -name "*.html" \) </code></pre> <hr> <p>You'd need to build that command line programmatically, which isn't that easy.</p> <p>Are you using bash (or Cygwin on Windows)? If you are, you should be able to do this:</p> <pre><c... | 390, 10193 | find, shell | <h1>Using find to locate files that match one of multiple patterns</h1>
<p>I was trying to get a list of all python and html files in a directory with the command <code>find Documents -name "*.{py,html}"</code>.</p>
<p>Then along came the man page:</p>
<blockquote>
<p>Braces within the pattern (‘{}’) are not consid... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 264 | bash | # Using find to locate files that match one of multiple patterns
I was trying to get a list of all python and html files in a directory with the command `find Documents -name "*.{py,html}"`.
Then along came the man page:
> Braces within the pattern (‘{}’) are not considered to be special (that is, find . -name 'foo{... | Use `-o`, which means "or":
```
find Documents \( -name "*.py" -o -name "*.html" \)
```
---
You'd need to build that command line programmatically, which isn't that easy.
Are you using bash (or Cygwin on Windows)? If you are, you should be able to do this:
```
ls **/*.py **/*.html
```
which might be easier to bui... |
4676459 | Write to file, but overwrite it if it exists | 421 | 2011-01-13 03:15:37 | <pre><code>echo "text" >> 'Users/Name/Desktop/TheAccount.txt'
</code></pre>
<p>How do I make it so it creates the file if it doesn't exist, but overwrites it if it already exists. Right now this script just appends.</p>
| 535,540 | 240,569 | 2025-04-23 18:46:20 | 4,676,473 | 652 | 2011-01-13 03:18:15 | 247,824 | 2020-07-02 17:34:56 | https://stackoverflow.com/q/4676459 | https://stackoverflow.com/a/4676473 | <p>The <code>>></code> redirection operator will append lines to the end of the specified file, where-as the single greater than <code>></code> will empty and overwrite the file.</p>
<pre><code>echo "text" > 'Users/Name/Desktop/TheAccount.txt'
</code></pre>
| <p>The <code>>></code> redirection operator will append lines to the end of the specified file, where-as the single greater than <code>></code> will empty and overwrite the file.</p> <pre><code>echo "text" > 'Users/Name/Desktop/TheAccount.txt' </code></pre> | 34, 387 | bash, unix | <h1>Write to file, but overwrite it if it exists</h1>
<pre><code>echo "text" >> 'Users/Name/Desktop/TheAccount.txt'
</code></pre>
<p>How do I make it so it creates the file if it doesn't exist, but overwrites it if it already exists. Right now this script just appends.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 265 | bash | # Write to file, but overwrite it if it exists
```
echo "text" >> 'Users/Name/Desktop/TheAccount.txt'
```
How do I make it so it creates the file if it doesn't exist, but overwrites it if it already exists. Right now this script just appends. | The `>>` redirection operator will append lines to the end of the specified file, where-as the single greater than `>` will empty and overwrite the file.
```
echo "text" > 'Users/Name/Desktop/TheAccount.txt'
``` |
6114119 | How do I read the first line of a file using cat? | 360 | 2011-05-24 17:04:42 | <p>How do I read the first line of a file using <code>cat</code>?</p>
| 415,757 | 601,095 | 2020-11-03 23:35:45 | 6,114,132 | 647 | 2011-05-24 17:06:12 | 116,908 | 2019-09-27 15:34:04 | https://stackoverflow.com/q/6114119 | https://stackoverflow.com/a/6114132 | <p>You don't need <code>cat</code>. </p>
<pre><code>head -1 file
</code></pre>
<p>will work fine.</p>
| <p>You don't need <code>cat</code>. </p> <pre><code>head -1 file </code></pre> <p>will work fine.</p> | 387, 724, 22820 | bash, cat, file-io | <h1>How do I read the first line of a file using cat?</h1>
<p>How do I read the first line of a file using <code>cat</code>?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 266 | bash | # How do I read the first line of a file using cat?
How do I read the first line of a file using `cat`? | You don't need `cat`.
```
head -1 file
```
will work fine. |
10523415 | Execute command on all files in a directory | 467 | 2012-05-09 20:12:42 | <p>Could somebody please provide the code to do the following:
Assume there is a directory of files, all of which need to be run through a program. The program outputs the results to standard out. I need a script that will go into a directory, execute the command on each file, and concat the output into one big output ... | 619,964 | 370,639 | 2024-08-30 16:17:01 | 10,523,501 | 646 | 2012-05-09 20:18:24 | 966,590 | 2015-11-24 13:28:34 | https://stackoverflow.com/q/10523415 | https://stackoverflow.com/a/10523501 | <p>The following bash code will pass $file to command where $file will represent every file in /dir</p>
<pre><code>for file in /dir/*
do
cmd [option] "$file" >> results.out
done
</code></pre>
<p>Example</p>
<pre><code>el@defiant ~/foo $ touch foo.txt bar.txt baz.txt
el@defiant ~/foo $ for i in *.txt; do echo... | <p>The following bash code will pass $file to command where $file will represent every file in /dir</p> <pre><code>for file in /dir/* do cmd [option] "$file" >> results.out done </code></pre> <p>Example</p> <pre><code>el@defiant ~/foo $ touch foo.txt bar.txt baz.txt el@defiant ~/foo $ for i in *.txt; do echo... | 387, 531 | bash, scripting | <h1>Execute command on all files in a directory</h1>
<p>Could somebody please provide the code to do the following:
Assume there is a directory of files, all of which need to be run through a program. The program outputs the results to standard out. I need a script that will go into a directory, execute the command on ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 267 | bash | # Execute command on all files in a directory
Could somebody please provide the code to do the following:
Assume there is a directory of files, all of which need to be run through a program. The program outputs the results to standard out. I need a script that will go into a directory, execute the command on each file... | The following bash code will pass $file to command where $file will represent every file in /dir
```
for file in /dir/*
do
cmd [option] "$file" >> results.out
done
```
Example
```
el@defiant ~/foo $ touch foo.txt bar.txt baz.txt
el@defiant ~/foo $ for i in *.txt; do echo "hello $i"; done
hello bar.txt
hello baz.tx... |
1221833 | Pipe output and capture exit status in Bash | 548 | 2009-08-03 11:31:52 | <p>I want to execute a long running command in Bash, and both capture its exit status, and <a href="http://en.wikipedia.org/wiki/Tee_(command)" rel="noreferrer">tee</a> its output.</p>
<p>So I do this:</p>
<pre><code>command | tee out.txt
ST=$?
</code></pre>
<p>The problem is that the variable ST captures the exit s... | 224,275 | 63,051 | 2024-04-19 23:41:30 | 1,221,870 | 644 | 2009-08-03 11:40:20 | 429,467 | 2016-12-21 17:17:14 | https://stackoverflow.com/q/1221833 | https://stackoverflow.com/a/1221870 | <p>There is an internal Bash variable called <code>$PIPESTATUS</code>; it’s an array that holds the exit status of each command in your last foreground pipeline of commands.</p>
<pre><code><command> | tee out.txt ; test ${PIPESTATUS[0]} -eq 0
</code></pre>
<p>Or another alternative which also works with other s... | <p>There is an internal Bash variable called <code>$PIPESTATUS</code>; it’s an array that holds the exit status of each command in your last foreground pipeline of commands.</p> <pre><code><command> | tee out.txt ; test ${PIPESTATUS[0]} -eq 0 </code></pre> <p>Or another alternative which also works with other s... | 379, 387, 390, 5813 | bash, error-handling, pipe, shell | <h1>Pipe output and capture exit status in Bash</h1>
<p>I want to execute a long running command in Bash, and both capture its exit status, and <a href="http://en.wikipedia.org/wiki/Tee_(command)" rel="noreferrer">tee</a> its output.</p>
<p>So I do this:</p>
<pre><code>command | tee out.txt
ST=$?
</code></pre>
<p>Th... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 268 | bash | # Pipe output and capture exit status in Bash
I want to execute a long running command in Bash, and both capture its exit status, and [tee](http://en.wikipedia.org/wiki/Tee_(command)) its output.
So I do this:
```
command | tee out.txt
ST=$?
```
The problem is that the variable ST captures the exit status of `tee` ... | There is an internal Bash variable called `$PIPESTATUS`; it’s an array that holds the exit status of each command in your last foreground pipeline of commands.
```
<command> | tee out.txt ; test ${PIPESTATUS[0]} -eq 0
```
Or another alternative which also works with other shells (like zsh) would be to enable pipefail... |
6363441 | Check if a file exists with a wildcard in a shell script | 419 | 2011-06-15 19:50:26 | <p>I'm trying to check if a file exists, but with a wildcard. Here is my example:</p>
<pre><code>if [ -f "xorg-x11-fonts*" ]; then
printf "BLAH"
fi
</code></pre>
<p>I have also tried it without the double quotes.</p>
| 506,748 | 695,727 | 2021-12-06 15:59:40 | 6,364,244 | 643 | 2011-06-15 20:56:02 | 262,683 | 2021-10-07 10:26:34 | https://stackoverflow.com/q/6363441 | https://stackoverflow.com/a/6364244 | <p>For Bash scripts, the most direct and performant approach is:</p>
<pre class="lang-sh prettyprint-override"><code>if compgen -G "${PROJECT_DIR}/*.png" > /dev/null; then
echo "pattern exists!"
fi
</code></pre>
<p>This will work very speedily even in directories with millions of files and do... | <p>For Bash scripts, the most direct and performant approach is:</p> <pre class="lang-sh prettyprint-override"><code>if compgen -G "${PROJECT_DIR}/*.png" > /dev/null; then echo "pattern exists!" fi </code></pre> <p>This will work very speedily even in directories with millions of files and do... | 390, 5997, 10327 | sh, shell, wildcard | <h1>Check if a file exists with a wildcard in a shell script</h1>
<p>I'm trying to check if a file exists, but with a wildcard. Here is my example:</p>
<pre><code>if [ -f "xorg-x11-fonts*" ]; then
printf "BLAH"
fi
</code></pre>
<p>I have also tried it without the double quotes.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 269 | bash | # Check if a file exists with a wildcard in a shell script
I'm trying to check if a file exists, but with a wildcard. Here is my example:
```
if [ -f "xorg-x11-fonts*" ]; then
printf "BLAH"
fi
```
I have also tried it without the double quotes. | For Bash scripts, the most direct and performant approach is:
```
if compgen -G "${PROJECT_DIR}/*.png" > /dev/null; then
echo "pattern exists!"
fi
```
This will work very speedily even in directories with millions of files and does not involve a new subshell.
[Source](https://stackoverflow.com/a/34195247/430062)... |
18681595 | Tar a directory, but don't store full absolute paths in the archive | 512 | 2013-09-08 07:43:34 | <p>I have the following command in the part of a backup shell script:</p>
<pre><code>tar -cjf site1.bz2 /var/www/site1/
</code></pre>
<p>When I list the contents of the archive, I get:</p>
<pre><code>tar -tf site1.bz2
var/www/site1/style.css
var/www/site1/index.html
var/www/site1/page2.html
var/www/site1/page3.html
... | 388,516 | 1,971,216 | 2024-08-09 10:58:20 | 18,681,628 | 638 | 2013-09-08 07:49:53 | 1,427,529 | 2015-06-11 09:50:34 | https://stackoverflow.com/q/18681595 | https://stackoverflow.com/a/18681628 | <pre><code>tar -cjf site1.tar.bz2 -C /var/www/site1 .
</code></pre>
<p>In the above example, tar will change to directory <code>/var/www/site1</code> before doing its thing because the option <code>-C /var/www/site1</code> was given.</p>
<p>From <code>man tar</code>:</p>
<pre><code>OTHER OPTIONS
-C, --directory D... | <pre><code>tar -cjf site1.tar.bz2 -C /var/www/site1 . </code></pre> <p>In the above example, tar will change to directory <code>/var/www/site1</code> before doing its thing because the option <code>-C /var/www/site1</code> was given.</p> <p>From <code>man tar</code>:</p> <pre><code>OTHER OPTIONS -C, --directory D... | 58, 387, 493, 8773 | backup, bash, linux, tar | <h1>Tar a directory, but don't store full absolute paths in the archive</h1>
<p>I have the following command in the part of a backup shell script:</p>
<pre><code>tar -cjf site1.bz2 /var/www/site1/
</code></pre>
<p>When I list the contents of the archive, I get:</p>
<pre><code>tar -tf site1.bz2
var/www/site1/style.cs... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 270 | bash | # Tar a directory, but don't store full absolute paths in the archive
I have the following command in the part of a backup shell script:
```
tar -cjf site1.bz2 /var/www/site1/
```
When I list the contents of the archive, I get:
```
tar -tf site1.bz2
var/www/site1/style.css
var/www/site1/index.html
var/www/site1/pag... | ```
tar -cjf site1.tar.bz2 -C /var/www/site1 .
```
In the above example, tar will change to directory `/var/www/site1` before doing its thing because the option `-C /var/www/site1` was given.
From `man tar`:
```
OTHER OPTIONS
-C, --directory DIR
change to directory DIR
``` |
2019857 | Diff files present in two different directories | 455 | 2010-01-07 11:25:54 | <p>I have two directories with the same list of files. I need to compare all the files present in both the directories using the <code>diff</code> command. Is there a simple command line option to do it, or do I have to write a shell script to get the file listing and then iterate through them?</p>
| 449,636 | 24,949 | 2024-11-08 10:30:23 | 2,019,897 | 634 | 2010-01-07 11:31:33 | 121,278 | 2017-01-19 16:14:27 | https://stackoverflow.com/q/2019857 | https://stackoverflow.com/a/2019897 | <p>You can use the <code>diff</code> command for that:</p>
<pre><code>diff -bur folder1/ folder2/
</code></pre>
<p>This will output a recursive diff that ignore spaces, with a unified context:</p>
<ul>
<li><strong>b</strong> flag means ignoring whitespace</li>
<li><strong>u</strong> flag means a unified context (3 l... | <p>You can use the <code>diff</code> command for that:</p> <pre><code>diff -bur folder1/ folder2/ </code></pre> <p>This will output a recursive diff that ignore spaces, with a unified context:</p> <ul> <li><strong>b</strong> flag means ignoring whitespace</li> <li><strong>u</strong> flag means a unified context (3 l... | 34, 390, 606 | diff, shell, unix | <h1>Diff files present in two different directories</h1>
<p>I have two directories with the same list of files. I need to compare all the files present in both the directories using the <code>diff</code> command. Is there a simple command line option to do it, or do I have to write a shell script to get the file listin... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 271 | bash | # Diff files present in two different directories
I have two directories with the same list of files. I need to compare all the files present in both the directories using the `diff` command. Is there a simple command line option to do it, or do I have to write a shell script to get the file listing and then iterate t... | You can use the `diff` command for that:
```
diff -bur folder1/ folder2/
```
This will output a recursive diff that ignore spaces, with a unified context:
- **b** flag means ignoring whitespace
- **u** flag means a unified context (3 lines before and after)
- **r** flag means recursive |
4509624 | How to limit depth for recursive file list? | 453 | 2010-12-22 13:28:02 | <p>Is there a way to limit the depth of a recursive file listing in linux?</p>
<p>The command I'm using at the moment is:</p>
<pre><code>ls -laR > dirlist.txt
</code></pre>
<p>But I've got about 200 directories and each of them have 10's of directories. So it's just going to take far too long and hog too many sys... | 458,808 | 177,132 | 2019-10-28 06:19:12 | 4,509,648 | 632 | 2010-12-22 13:31:29 | 57,095 | 2010-12-22 13:39:15 | https://stackoverflow.com/q/4509624 | https://stackoverflow.com/a/4509648 | <p>Checkout the <code>-maxdepth</code> flag of <code>find</code></p>
<pre><code>find . -maxdepth 1 -type d -exec ls -ld "{}" \;
</code></pre>
<p>Here I used 1 as max level depth, <code>-type d</code> means find only directories, which then <code>ls -ld</code> lists contents of, in long format.</p>
| <p>Checkout the <code>-maxdepth</code> flag of <code>find</code></p> <pre><code>find . -maxdepth 1 -type d -exec ls -ld "{}" \; </code></pre> <p>Here I used 1 as max level depth, <code>-type d</code> means find only directories, which then <code>ls -ld</code> lists contents of, in long format.</p> | 58, 387 | bash, linux | <h1>How to limit depth for recursive file list?</h1>
<p>Is there a way to limit the depth of a recursive file listing in linux?</p>
<p>The command I'm using at the moment is:</p>
<pre><code>ls -laR > dirlist.txt
</code></pre>
<p>But I've got about 200 directories and each of them have 10's of directories. So it's... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 272 | bash | # How to limit depth for recursive file list?
Is there a way to limit the depth of a recursive file listing in linux?
The command I'm using at the moment is:
```
ls -laR > dirlist.txt
```
But I've got about 200 directories and each of them have 10's of directories. So it's just going to take far too long and hog to... | Checkout the `-maxdepth` flag of `find`
```
find . -maxdepth 1 -type d -exec ls -ld "{}" \;
```
Here I used 1 as max level depth, `-type d` means find only directories, which then `ls -ld` lists contents of, in long format. |
18428374 | in mac always getting zsh: command not found: | 370 | 2013-08-25 11:12:35 | <p>I am using the z Shell (<code>zsh</code>) instead of the default bash, and something wrong happen so that all commands that used to work are no longer recognized:</p>
<pre class="lang-bash prettyprint-override"><code> ls
zsh: command not found: ls
open -e .zshrc
zsh: correct 'open' to '_open' [nyae]?... | 1,218,738 | 602,257 | 2023-04-20 16:47:28 | 18,428,774 | 628 | 2013-08-25 12:04:49 | 2,235,132 | 2023-04-20 16:47:28 | https://stackoverflow.com/q/18428374 | https://stackoverflow.com/a/18428774 | <p>It's evident that you've managed to mess up your <code>PATH</code> variable. (Your current <code>PATH</code> doesn't contain any location where common utilities are located.)</p>
<p>Try:</p>
<pre><code>PATH=/bin:/usr/bin:/usr/local/bin:/sbin:${PATH}
export PATH
</code></pre>
<p>Alternatively, for "resetting&qu... | <p>It's evident that you've managed to mess up your <code>PATH</code> variable. (Your current <code>PATH</code> doesn't contain any location where common utilities are located.)</p> <p>Try:</p> <pre><code>PATH=/bin:/usr/bin:/usr/local/bin:/sbin:${PATH} export PATH </code></pre> <p>Alternatively, for "resetting&qu... | 390, 3791, 71219 | osx-lion, shell, zsh | <h1>in mac always getting zsh: command not found:</h1>
<p>I am using the z Shell (<code>zsh</code>) instead of the default bash, and something wrong happen so that all commands that used to work are no longer recognized:</p>
<pre class="lang-bash prettyprint-override"><code> ls
zsh: command not found: ls
op... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 273 | bash | # in mac always getting zsh: command not found:
I am using the z Shell (`zsh`) instead of the default bash, and something wrong happen so that all commands that used to work are no longer recognized:
```
ls
zsh: command not found: ls
open -e .zshrc
zsh: correct 'open' to '_open' [nyae]?
```
I don't ... | It's evident that you've managed to mess up your `PATH` variable. (Your current `PATH` doesn't contain any location where common utilities are located.)
Try:
```
PATH=/bin:/usr/bin:/usr/local/bin:/sbin:${PATH}
export PATH
```
Alternatively, for "resetting" zsh, specify the complete path to the shell:
```
exec /bin/... |
4247068 | sed command with -i option failing on Mac, but works on Linux | 477 | 2010-11-22 15:33:49 | <p>I've successfully used the following <code>sed</code> command to search/replace text in Linux:</p>
<pre><code>sed -i 's/old_link/new_link/g' *
</code></pre>
<p>However, when I try it on my Mac OS X, I get:</p>
<blockquote>
<p>"command c expects \ followed by text"</p>
</blockquote>
<p>I thought my Mac runs a n... | 396,489 | 165,673 | 2025-01-09 00:33:41 | 4,247,319 | 626 | 2010-11-22 15:53:28 | 515,275 | 2025-01-09 00:33:41 | https://stackoverflow.com/q/4247068 | https://stackoverflow.com/a/4247319 | <blockquote>
<p><strong>Portable solution</strong> below</p>
</blockquote>
<h3>Why you get the error</h3>
<p>The <code>-i</code> option (alternatively, <code>--in-place</code>) means that you want files edited in-place, rather than streaming the change to a new place.</p>
<p>Modifying a file in-place suggests a need fo... | <blockquote> <p><strong>Portable solution</strong> below</p> </blockquote> <h3>Why you get the error</h3> <p>The <code>-i</code> option (alternatively, <code>--in-place</code>) means that you want files edited in-place, rather than streaming the change to a new place.</p> <p>Modifying a file in-place suggests a need fo... | 58, 369, 387, 5282 | bash, linux, macos, sed | <h1>sed command with -i option failing on Mac, but works on Linux</h1>
<p>I've successfully used the following <code>sed</code> command to search/replace text in Linux:</p>
<pre><code>sed -i 's/old_link/new_link/g' *
</code></pre>
<p>However, when I try it on my Mac OS X, I get:</p>
<blockquote>
<p>"command c expe... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 274 | bash | # sed command with -i option failing on Mac, but works on Linux
I've successfully used the following `sed` command to search/replace text in Linux:
```
sed -i 's/old_link/new_link/g' *
```
However, when I try it on my Mac OS X, I get:
> "command c expects \ followed by text"
I thought my Mac runs a normal BASH she... | > **Portable solution** below
### Why you get the error
The `-i` option (alternatively, `--in-place`) means that you want files edited in-place, rather than streaming the change to a new place.
Modifying a file in-place suggests a need for a backup file - and so a user-specified extension is expected after `-i`, but... |
21112707 | Check if a string matches a regex in Bash script | 403 | 2014-01-14 11:43:09 | <p>One of the arguments that my script receives is a date in the following format: <code>yyyymmdd</code>.</p>
<p>I want to check if I get a valid date as an input.</p>
<p>How can I do this? I am trying to use a regex like: <code>[0-9]\{\8}</code></p>
| 651,553 | 3,145,943 | 2022-08-22 22:11:17 | 21,112,809 | 626 | 2014-01-14 11:47:58 | 1,983,854 | 2022-03-29 17:48:44 | https://stackoverflow.com/q/21112707 | https://stackoverflow.com/a/21112809 | <p>You can use the test construct, <code>[[ ]]</code>, along with the regular expression match operator, <code>=~</code>, to check if a string matches a regex pattern (<a href="https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html#index-_005b_005b" rel="noreferrer">documentation</a>).</p>
<p>Fo... | <p>You can use the test construct, <code>[[ ]]</code>, along with the regular expression match operator, <code>=~</code>, to check if a string matches a regex pattern (<a href="https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html#index-_005b_005b" rel="noreferrer">documentation</a>).</p> <p>Fo... | 18, 387, 390, 531 | bash, regex, scripting, shell | <h1>Check if a string matches a regex in Bash script</h1>
<p>One of the arguments that my script receives is a date in the following format: <code>yyyymmdd</code>.</p>
<p>I want to check if I get a valid date as an input.</p>
<p>How can I do this? I am trying to use a regex like: <code>[0-9]\{\8}</code></p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 275 | bash | # Check if a string matches a regex in Bash script
One of the arguments that my script receives is a date in the following format: `yyyymmdd`.
I want to check if I get a valid date as an input.
How can I do this? I am trying to use a regex like: `[0-9]\{\8}` | You can use the test construct, `[[ ]]`, along with the regular expression match operator, `=~`, to check if a string matches a regex pattern ([documentation](https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html#index-_005b_005b)).
For your specific case, you can write:
```
[[ "$date" =~ ^[0... |
3358420 | Generating a SHA-256 hash from the Linux command line | 401 | 2010-07-28 23:41:05 | <p>I know the string "foobar" generates the SHA-256 hash <code>c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2</code> using
<a href="http://hash.online-convert.com/sha256-generator" rel="noreferrer">http://hash.online-convert.com/sha256-generator</a></p>
<p>However the command line shell:</p>
<pre><c... | 617,785 | 4,534 | 2024-05-17 12:42:20 | 3,358,428 | 622 | 2010-07-28 23:43:12 | 371,793 | 2015-06-03 02:46:20 | https://stackoverflow.com/q/3358420 | https://stackoverflow.com/a/3358428 | <p><code>echo</code> will normally output a newline, which is suppressed with <code>-n</code>. Try this:</p>
<pre><code>echo -n foobar | sha256sum
</code></pre>
| <p><code>echo</code> will normally output a newline, which is suppressed with <code>-n</code>. Try this:</p> <pre><code>echo -n foobar | sha256sum </code></pre> | 58, 390, 13892 | linux, sha256, shell | <h1>Generating a SHA-256 hash from the Linux command line</h1>
<p>I know the string "foobar" generates the SHA-256 hash <code>c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2</code> using
<a href="http://hash.online-convert.com/sha256-generator" rel="noreferrer">http://hash.online-convert.com/sha256-gen... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 276 | bash | # Generating a SHA-256 hash from the Linux command line
I know the string "foobar" generates the SHA-256 hash `c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2` using
<http://hash.online-convert.com/sha256-generator>
However the command line shell:
```
hendry@x201 ~$ echo foobar | sha256sum
aec070645... | `echo` will normally output a newline, which is suppressed with `-n`. Try this:
```
echo -n foobar | sha256sum
``` |
2609552 | How can I use ":" as an AWK field separator? | 402 | 2010-04-09 17:30:51 | <p>Given the following command,</p>
<pre><code>echo "1: " | awk '/1/ -F ":" {print $1}'
</code></pre>
<p>why does AWK output:</p>
<pre><code>1:
</code></pre>
<p>?</p>
| 914,335 | 173,446 | 2025-01-13 10:12:21 | 2,609,565 | 621 | 2010-04-09 17:33:25 | 308,679 | 2022-10-14 16:39:25 | https://stackoverflow.com/q/2609552 | https://stackoverflow.com/a/2609565 | <p><code>-F</code> is a command line argument, not AWK syntax. Try:</p>
<pre class="lang-bash prettyprint-override"><code>echo '1: ' | awk -F ':' '/1/ {print $1}'
</code></pre>
| <p><code>-F</code> is a command line argument, not AWK syntax. Try:</p> <pre class="lang-bash prettyprint-override"><code>echo '1: ' | awk -F ':' '/1/ {print $1}' </code></pre> | 387, 990 | awk, bash | <h1>How can I use ":" as an AWK field separator?</h1>
<p>Given the following command,</p>
<pre><code>echo "1: " | awk '/1/ -F ":" {print $1}'
</code></pre>
<p>why does AWK output:</p>
<pre><code>1:
</code></pre>
<p>?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 277 | bash | # How can I use ":" as an AWK field separator?
Given the following command,
```
echo "1: " | awk '/1/ -F ":" {print $1}'
```
why does AWK output:
```
1:
```
? | `-F` is a command line argument, not AWK syntax. Try:
```
echo '1: ' | awk -F ':' '/1/ {print $1}'
``` |
8961334 | How to change folder with git bash? | 353 | 2012-01-22 13:15:33 | <p>My default <code>git</code> folder is <code>C:\Users\username\.git</code>.</p>
<p>What command should I use to go into <code>C:/project</code>?</p>
| 1,186,972 | 1,124,803 | 2022-04-18 19:16:22 | 8,961,349 | 621 | 2012-01-22 13:17:39 | 19,165 | 2019-10-15 08:01:04 | https://stackoverflow.com/q/8961334 | https://stackoverflow.com/a/8961349 | <p>The command is:</p>
<pre><code>cd /c/project/
</code></pre>
<p><strong>Tip:</strong><br>
Use the <code>pwd</code> command to see which path you are currently in, handy when you did a right-click "Git Bash here..."</p>
| <p>The command is:</p> <pre><code>cd /c/project/ </code></pre> <p><strong>Tip:</strong><br> Use the <code>pwd</code> command to see which path you are currently in, handy when you did a right-click "Git Bash here..."</p> | 119, 61874 | git, git-bash | <h1>How to change folder with git bash?</h1>
<p>My default <code>git</code> folder is <code>C:\Users\username\.git</code>.</p>
<p>What command should I use to go into <code>C:/project</code>?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 278 | bash | # How to change folder with git bash?
My default `git` folder is `C:\Users\username\.git`.
What command should I use to go into `C:/project`? | The command is:
```
cd /c/project/
```
**Tip:**
Use the `pwd` command to see which path you are currently in, handy when you did a right-click "Git Bash here..." |
7909167 | How to quietly remove a directory with content in PowerShell | 422 | 2011-10-26 21:29:17 | <p>Using PowerShell, is it possible to remove some directory that contains files without prompting to confirm action?</p>
| 642,517 | 223,386 | 2023-08-05 12:43:26 | 7,909,195 | 620 | 2011-10-26 21:32:09 | 985,032 | 2022-09-16 13:30:08 | https://stackoverflow.com/q/7909167 | https://stackoverflow.com/a/7909195 | <pre><code>Remove-Item -LiteralPath "foldertodelete" -Force -Recurse
</code></pre>
<p>or, with shorter version</p>
<pre><code>rm /path -r -force
</code></pre>
| <pre><code>Remove-Item -LiteralPath "foldertodelete" -Force -Recurse </code></pre> <p>or, with shorter version</p> <pre><code>rm /path -r -force </code></pre> | 218, 526 | directory, powershell | <h1>How to quietly remove a directory with content in PowerShell</h1>
<p>Using PowerShell, is it possible to remove some directory that contains files without prompting to confirm action?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 279 | bash | # How to quietly remove a directory with content in PowerShell
Using PowerShell, is it possible to remove some directory that contains files without prompting to confirm action? | ```
Remove-Item -LiteralPath "foldertodelete" -Force -Recurse
```
or, with shorter version
```
rm /path -r -force
``` |
4412238 | What is the cleanest way to ssh and run multiple commands in Bash? | 485 | 2010-12-10 18:50:48 | <p>I already have an ssh agent set up, and I can run commands on an external server in Bash script doing stuff like:</p>
<pre><code>ssh blah_server "ls; pwd;"
</code></pre>
<p>Now, what I'd really like to do is run a lot of long commands on an external server. Enclosing all of these in between quotation marks... | 595,242 | 392,975 | 2025-01-14 16:13:38 | 4,412,338 | 618 | 2010-12-10 19:03:15 | 3,333 | 2017-11-15 02:14:17 | https://stackoverflow.com/q/4412238 | https://stackoverflow.com/a/4412338 | <p>How about a Bash <a href="http://www.tldp.org/LDP/abs/html/here-docs.html" rel="noreferrer">Here Document</a>:</p>
<pre><code>ssh otherhost << EOF
ls some_folder;
./someaction.sh 'some params'
pwd
./some_other_action 'other params'
EOF
</code></pre>
<p>To avoid the problems mentioned by @Globalz in ... | <p>How about a Bash <a href="http://www.tldp.org/LDP/abs/html/here-docs.html" rel="noreferrer">Here Document</a>:</p> <pre><code>ssh otherhost << EOF ls some_folder; ./someaction.sh 'some params' pwd ./some_other_action 'other params' EOF </code></pre> <p>To avoid the problems mentioned by @Globalz in ... | 34, 386, 387 | bash, ssh, unix | <h1>What is the cleanest way to ssh and run multiple commands in Bash?</h1>
<p>I already have an ssh agent set up, and I can run commands on an external server in Bash script doing stuff like:</p>
<pre><code>ssh blah_server "ls; pwd;"
</code></pre>
<p>Now, what I'd really like to do is run a lot of long comma... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 280 | bash | # What is the cleanest way to ssh and run multiple commands in Bash?
I already have an ssh agent set up, and I can run commands on an external server in Bash script doing stuff like:
```
ssh blah_server "ls; pwd;"
```
Now, what I'd really like to do is run a lot of long commands on an external server. Enclosing all ... | How about a Bash [Here Document](http://www.tldp.org/LDP/abs/html/here-docs.html):
```
ssh otherhost << EOF
ls some_folder;
./someaction.sh 'some params'
pwd
./some_other_action 'other params'
EOF
```
To avoid the problems mentioned by @Globalz in the comments, you may be able to (depending what you're doing... |
13322485 | How to get the primary IP address of the local machine on Linux and OS X? | 477 | 2012-11-10 13:32:11 | <p>I am looking for a command line solution that would return me the primary (first) IP address of the localhost, other than 127.0.0.1</p>
<p>The solution should work at least for Linux (Debian and RedHat) and OS X 10.7+</p>
<p>I am aware that <code>ifconfig</code> is available on both but its output is not so consis... | 983,879 | 99,834 | 2024-02-19 07:14:15 | 13,322,549 | 618 | 2012-11-10 13:39:13 | 1,066,031 | 2018-01-12 22:14:17 | https://stackoverflow.com/q/13322485 | https://stackoverflow.com/a/13322549 | <p>Use <code>grep</code> to filter IP address from <code>ifconfig</code>: </p>
<p><code>ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'</code></p>
<p>Or with <code>sed</code>:</p>
<p><code>ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[... | <p>Use <code>grep</code> to filter IP address from <code>ifconfig</code>: </p> <p><code>ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'</code></p> <p>Or with <code>sed</code>:</p> <p><code>ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[... | 34, 294, 387, 30175 | bash, ifconfig, ip, unix | <h1>How to get the primary IP address of the local machine on Linux and OS X?</h1>
<p>I am looking for a command line solution that would return me the primary (first) IP address of the localhost, other than 127.0.0.1</p>
<p>The solution should work at least for Linux (Debian and RedHat) and OS X 10.7+</p>
<p>I am aw... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 281 | bash | # How to get the primary IP address of the local machine on Linux and OS X?
I am looking for a command line solution that would return me the primary (first) IP address of the localhost, other than 127.0.0.1
The solution should work at least for Linux (Debian and RedHat) and OS X 10.7+
I am aware that `ifconfig` is ... | Use `grep` to filter IP address from `ifconfig`:
`ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'`
Or with `sed`:
`ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'`
If you are only interested in certain interfaces, wlan0, ... |
307503 | What's a concise way to check that environment variables are set in a Unix shell script? | 526 | 2008-11-21 01:11:27 | <p>I've got a few Unix shell scripts where I need to check that certain environment variables are set before I start doing stuff, so I do this sort of thing:</p>
<pre><code>if [ -z "$STATE" ]; then
echo "Need to set STATE"
exit 1
fi
if [ -z "$DEST" ]; then
echo "Need to set DEST"
exit 1
fi
</code></... | 404,586 | 2,994 | 2024-05-13 15:28:16 | 307,735 | 616 | 2008-11-21 03:25:31 | 15,168 | 2015-10-06 19:36:18 | https://stackoverflow.com/q/307503 | https://stackoverflow.com/a/307735 | <h3>Parameter Expansion</h3>
<p>The obvious answer is to use one of the special forms of parameter expansion:</p>
<pre><code>: ${STATE?"Need to set STATE"}
: ${DEST:?"Need to set DEST non-empty"}
</code></pre>
<p>Or, better (see section on 'Position of double quotes' below):</p>
<pre><code>: "$... | <h3>Parameter Expansion</h3> <p>The obvious answer is to use one of the special forms of parameter expansion:</p> <pre><code>: ${STATE?"Need to set STATE"} : ${DEST:?"Need to set DEST non-empty"} </code></pre> <p>Or, better (see section on 'Position of double quotes' below):</p> <pre><code>: "$... | 34, 387, 390 | bash, shell, unix | <h1>What's a concise way to check that environment variables are set in a Unix shell script?</h1>
<p>I've got a few Unix shell scripts where I need to check that certain environment variables are set before I start doing stuff, so I do this sort of thing:</p>
<pre><code>if [ -z "$STATE" ]; then
echo "Need to set S... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 282 | bash | # What's a concise way to check that environment variables are set in a Unix shell script?
I've got a few Unix shell scripts where I need to check that certain environment variables are set before I start doing stuff, so I do this sort of thing:
```
if [ -z "$STATE" ]; then
echo "Need to set STATE"
exit 1
fi ... | ### Parameter Expansion
The obvious answer is to use one of the special forms of parameter expansion:
```
: ${STATE?"Need to set STATE"}
: ${DEST:?"Need to set DEST non-empty"}
```
Or, better (see section on 'Position of double quotes' below):
```
: "${STATE?Need to set STATE}"
: "${DEST:?Need to set DEST non-empty... |
2924697 | How does one output bold text in Bash? | 371 | 2010-05-27 20:36:09 | <p>I'm writing a Bash script that prints some text to the screen:</p>
<pre><code>echo "Some Text"
</code></pre>
<p>Can I format the text? I would like to make it bold.</p>
| 317,735 | 335,937 | 2025-07-17 05:30:21 | 2,924,755 | 614 | 2010-05-27 20:42:16 | 333,698 | 2024-03-01 17:05:03 | https://stackoverflow.com/q/2924697 | https://stackoverflow.com/a/2924755 | <p>The most compatible way of doing this is using <code>tput</code> to discover the right sequences to send to the terminal:</p>
<pre><code>bold=$(tput bold)
normal=$(tput sgr0)
</code></pre>
<p>then you can use the variables <code>$bold</code> and <code>$normal</code> to format things:</p>
<pre><code>echo "this i... | <p>The most compatible way of doing this is using <code>tput</code> to discover the right sequences to send to the terminal:</p> <pre><code>bold=$(tput bold) normal=$(tput sgr0) </code></pre> <p>then you can use the variables <code>$bold</code> and <code>$normal</code> to format things:</p> <pre><code>echo "this i... | 387, 488, 555, 13824 | bash, console, echo, formatting | <h1>How does one output bold text in Bash?</h1>
<p>I'm writing a Bash script that prints some text to the screen:</p>
<pre><code>echo "Some Text"
</code></pre>
<p>Can I format the text? I would like to make it bold.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 283 | bash | # How does one output bold text in Bash?
I'm writing a Bash script that prints some text to the screen:
```
echo "Some Text"
```
Can I format the text? I would like to make it bold. | The most compatible way of doing this is using `tput` to discover the right sequences to send to the terminal:
```
bold=$(tput bold)
normal=$(tput sgr0)
```
then you can use the variables `$bold` and `$normal` to format things:
```
echo "this is ${bold}bold${normal} but this isn't"
```
gives
> this is **bold** but... |
40082346 | How to check if a file exists in a shell script | 338 | 2016-10-17 09:05:51 | <p>I'd like to write a shell script which checks if a certain file, <code>archived_sensor_data.json</code>, exists, and if so, deletes it. Following <a href="http://www.cyberciti.biz/tips/find-out-if-file-exists-with-conditional-expressions.html" rel="noreferrer">http://www.cyberciti.biz/tips/find-out-if-file-exists-wi... | 771,328 | 995,862 | 2024-02-08 19:28:10 | 40,082,454 | 613 | 2016-10-17 09:11:22 | 307,297 | 2018-11-01 20:54:26 | https://stackoverflow.com/q/40082346 | https://stackoverflow.com/a/40082454 | <p>You're missing a required space between the bracket and <code>-e</code>:</p>
<pre><code>#!/bin/bash
if [ -e x.txt ]
then
echo "ok"
else
echo "nok"
fi
</code></pre>
| <p>You're missing a required space between the bracket and <code>-e</code>:</p> <pre><code>#!/bin/bash if [ -e x.txt ] then echo "ok" else echo "nok" fi </code></pre> | 390 | shell | <h1>How to check if a file exists in a shell script</h1>
<p>I'd like to write a shell script which checks if a certain file, <code>archived_sensor_data.json</code>, exists, and if so, deletes it. Following <a href="http://www.cyberciti.biz/tips/find-out-if-file-exists-with-conditional-expressions.html" rel="noreferrer"... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 284 | bash | # How to check if a file exists in a shell script
I'd like to write a shell script which checks if a certain file, `archived_sensor_data.json`, exists, and if so, deletes it. Following <http://www.cyberciti.biz/tips/find-out-if-file-exists-with-conditional-expressions.html>, I've tried the following:
```
[-e archived... | You're missing a required space between the bracket and `-e`:
```
#!/bin/bash
if [ -e x.txt ]
then
echo "ok"
else
echo "nok"
fi
``` |
3162385 | How to split a string in shell and get the last field | 415 | 2010-07-01 23:29:38 | <p>Suppose I have the string <code>1:2:3:4:5</code> and I want to get its last field (<code>5</code> in this case). How do I do that using Bash? I tried <code>cut</code>, but I don't know how to specify the last field with <code>-f</code>.</p>
| 549,788 | 38,333 | 2025-01-21 17:39:32 | 3,162,500 | 609 | 2010-07-02 00:05:40 | 303,180 | 2010-07-02 00:05:40 | https://stackoverflow.com/q/3162385 | https://stackoverflow.com/a/3162500 | <p>You can use <a href="http://www.linuxjournal.com/article/8919" rel="noreferrer">string operators</a>:</p>
<pre><code>$ foo=1:2:3:4:5
$ echo ${foo##*:}
5
</code></pre>
<p>This trims everything from the front until a ':', greedily.</p>
<pre><code>${foo <-- from variable foo
## <-- greedy front trim
* ... | <p>You can use <a href="http://www.linuxjournal.com/article/8919" rel="noreferrer">string operators</a>:</p> <pre><code>$ foo=1:2:3:4:5 $ echo ${foo##*:} 5 </code></pre> <p>This trims everything from the front until a ':', greedily.</p> <pre><code>${foo <-- from variable foo ## <-- greedy front trim * ... | 387, 2193, 4257, 15047 | bash, cut, split, tokenize | <h1>How to split a string in shell and get the last field</h1>
<p>Suppose I have the string <code>1:2:3:4:5</code> and I want to get its last field (<code>5</code> in this case). How do I do that using Bash? I tried <code>cut</code>, but I don't know how to specify the last field with <code>-f</code>.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 285 | bash | # How to split a string in shell and get the last field
Suppose I have the string `1:2:3:4:5` and I want to get its last field (`5` in this case). How do I do that using Bash? I tried `cut`, but I don't know how to specify the last field with `-f`. | You can use [string operators](http://www.linuxjournal.com/article/8919):
```
$ foo=1:2:3:4:5
$ echo ${foo##*:}
5
```
This trims everything from the front until a ':', greedily.
```
${foo <-- from variable foo
## <-- greedy front trim
* <-- matches anything
: <-- until the last ':'
}
``` |
3569997 | How to find out line-endings in a text file? | 501 | 2010-08-25 20:36:06 | <p>I'm trying to use something in bash to show me the line endings in a file printed rather than interpreted. The file is a dump from SSIS/SQL Server being read in by a Linux machine for processing.</p>
<ul>
<li><p>Are there any switches within <code>vi</code>, <code>less</code>, <code>more</code>, etc?</p></li>
<li><... | 587,701 | 196,832 | 2025-03-18 09:56:12 | 3,570,574 | 607 | 2010-08-25 22:00:50 | 26,428 | 2010-08-25 22:00:50 | https://stackoverflow.com/q/3569997 | https://stackoverflow.com/a/3570574 | <p>You can use the <code>file</code> utility to give you an indication of the type of line endings.</p>
<p>Unix:</p>
<pre><code>$ file testfile1.txt
testfile.txt: ASCII text
</code></pre>
<p>"DOS":</p>
<pre><code>$ file testfile2.txt
testfile2.txt: ASCII text, with CRLF line terminators
</code></pre>
<p>To convert... | <p>You can use the <code>file</code> utility to give you an indication of the type of line endings.</p> <p>Unix:</p> <pre><code>$ file testfile1.txt testfile.txt: ASCII text </code></pre> <p>"DOS":</p> <pre><code>$ file testfile2.txt testfile2.txt: ASCII text, with CRLF line terminators </code></pre> <p>To convert... | 58, 387, 1231, 3705, 8329 | bash, command-line, line-endings, linux, newline | <h1>How to find out line-endings in a text file?</h1>
<p>I'm trying to use something in bash to show me the line endings in a file printed rather than interpreted. The file is a dump from SSIS/SQL Server being read in by a Linux machine for processing.</p>
<ul>
<li><p>Are there any switches within <code>vi</code>, <co... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 286 | bash | # How to find out line-endings in a text file?
I'm trying to use something in bash to show me the line endings in a file printed rather than interpreted. The file is a dump from SSIS/SQL Server being read in by a Linux machine for processing.
- Are there any switches within `vi`, `less`, `more`, etc?
- In addition to... | You can use the `file` utility to give you an indication of the type of line endings.
Unix:
```
$ file testfile1.txt
testfile.txt: ASCII text
```
"DOS":
```
$ file testfile2.txt
testfile2.txt: ASCII text, with CRLF line terminators
```
To convert from "DOS" to Unix:
```
$ dos2unix testfile2.txt
```
To convert fr... |
4881930 | Remove the last line from a file in Bash | 483 | 2011-02-03 01:45:20 | <p>I have a file, <code>foo.txt</code>, containing the following lines:</p>
<pre><code>a
b
c
</code></pre>
<p>I want a simple command that results in the contents of <code>foo.txt</code> being:</p>
<pre><code>a
b
</code></pre>
| 609,679 | 121,112 | 2024-10-08 04:55:29 | 4,881,990 | 607 | 2011-02-03 01:59:52 | 507,519 | 2018-12-10 23:53:36 | https://stackoverflow.com/q/4881930 | https://stackoverflow.com/a/4881990 | <p>Using <a href="http://www.gnu.org/software/sed/" rel="noreferrer"><code>GNU sed</code></a>:</p>
<pre><code>sed -i '$ d' foo.txt
</code></pre>
<p>The <code>-i</code> option does not exist in <code>GNU sed</code> versions older than 3.95, so you have to use it as a filter with a temporary file:</p>
<pre><code>cp fo... | <p>Using <a href="http://www.gnu.org/software/sed/" rel="noreferrer"><code>GNU sed</code></a>:</p> <pre><code>sed -i '$ d' foo.txt </code></pre> <p>The <code>-i</code> option does not exist in <code>GNU sed</code> versions older than 3.95, so you have to use it as a filter with a temporary file:</p> <pre><code>cp fo... | 387, 531, 1231, 3601 | bash, command-line, scripting, truncate | <h1>Remove the last line from a file in Bash</h1>
<p>I have a file, <code>foo.txt</code>, containing the following lines:</p>
<pre><code>a
b
c
</code></pre>
<p>I want a simple command that results in the contents of <code>foo.txt</code> being:</p>
<pre><code>a
b
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 287 | bash | # Remove the last line from a file in Bash
I have a file, `foo.txt`, containing the following lines:
```
a
b
c
```
I want a simple command that results in the contents of `foo.txt` being:
```
a
b
``` | Using [`GNU sed`](http://www.gnu.org/software/sed/):
```
sed -i '$ d' foo.txt
```
The `-i` option does not exist in `GNU sed` versions older than 3.95, so you have to use it as a filter with a temporary file:
```
cp foo.txt foo.txt.tmp
sed '$ d' foo.txt.tmp > foo.txt
rm -f foo.txt.tmp
```
Of course, in that case yo... |
13593771 | Repeat command automatically in Linux | 352 | 2012-11-27 21:50:24 | <p>Is it possible in Linux command line to have a command repeat every <em>n</em> seconds?</p>
<p>Say, I have an import running, and I am doing</p>
<pre><code>ls -l
</code></pre>
<p>to check if the file size is increasing. I would like to have a command to have this repeat automatically.</p>
| 417,832 | 1,189,880 | 2024-11-02 18:49:01 | 13,593,790 | 607 | 2012-11-27 21:51:47 | 449,958 | 2012-11-27 22:05:33 | https://stackoverflow.com/q/13593771 | https://stackoverflow.com/a/13593790 | <p>Watch every 5 seconds ...</p>
<p><code>watch -n 5 ls -l</code></p>
<p>If you wish to have visual confirmation of changes, append <code>--differences</code> prior to the <code>ls</code> command.</p>
<p>According to the OSX man page, there's also</p>
<blockquote>
<p>The --cumulative option makes highlighting "st... | <p>Watch every 5 seconds ...</p> <p><code>watch -n 5 ls -l</code></p> <p>If you wish to have visual confirmation of changes, append <code>--differences</code> prior to the <code>ls</code> command.</p> <p>According to the OSX man page, there's also</p> <blockquote> <p>The --cumulative option makes highlighting "st... | 58, 387, 549 | bash, linux, ubuntu | <h1>Repeat command automatically in Linux</h1>
<p>Is it possible in Linux command line to have a command repeat every <em>n</em> seconds?</p>
<p>Say, I have an import running, and I am doing</p>
<pre><code>ls -l
</code></pre>
<p>to check if the file size is increasing. I would like to have a command to have this rep... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 288 | bash | # Repeat command automatically in Linux
Is it possible in Linux command line to have a command repeat every *n* seconds?
Say, I have an import running, and I am doing
```
ls -l
```
to check if the file size is increasing. I would like to have a command to have this repeat automatically. | Watch every 5 seconds ...
`watch -n 5 ls -l`
If you wish to have visual confirmation of changes, append `--differences` prior to the `ls` command.
According to the OSX man page, there's also
> The --cumulative option makes highlighting "sticky", presenting a
> running display of all positions that have ever changed... |
2085744 | How do I get the current username in Windows PowerShell? | 521 | 2010-01-18 11:50:32 | <p>How do I get the current username in Windows PowerShell?</p>
| 1,069,114 | 15,985 | 2025-06-30 00:44:33 | 2,085,755 | 605 | 2010-01-18 11:52:52 | 15,985 | 2023-05-15 19:47:58 | https://stackoverflow.com/q/2085744 | https://stackoverflow.com/a/2085755 | <p>I found it:</p>
<pre><code>[Environment]::UserName
$Env:UserName
</code></pre>
<p>There is also:</p>
<pre><code>$Env:UserDomain
$Env:ComputerName
</code></pre>
| <p>I found it:</p> <pre><code>[Environment]::UserName $Env:UserName </code></pre> <p>There is also:</p> <pre><code>$Env:UserDomain $Env:ComputerName </code></pre> | 64, 526, 531 | powershell, scripting, windows | <h1>How do I get the current username in Windows PowerShell?</h1>
<p>How do I get the current username in Windows PowerShell?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 289 | bash | # How do I get the current username in Windows PowerShell?
How do I get the current username in Windows PowerShell? | I found it:
```
[Environment]::UserName
$Env:UserName
```
There is also:
```
$Env:UserDomain
$Env:ComputerName
``` |
7526971 | How to redirect both stdout and stderr to a file | 387 | 2011-09-23 09:35:45 | <p>I am running a bash script that creates a log file for the execution of the command</p>
<p>I use the following</p>
<pre><code>Command1 >> log_file
Command2 >> log_file
</code></pre>
<p>This only sends the standard output and not the standard error which appears on the terminal.</p>
| 321,596 | 525,376 | 2021-12-15 12:48:19 | 7,526,988 | 605 | 2011-09-23 09:37:31 | 635,608 | 2011-09-23 09:37:31 | https://stackoverflow.com/q/7526971 | https://stackoverflow.com/a/7526988 | <p>If you want to log to the same file:</p>
<pre><code>command1 >> log_file 2>&1
</code></pre>
<p>If you want different files:</p>
<pre><code>command1 >> log_file 2>> err_file
</code></pre>
| <p>If you want to log to the same file:</p> <pre><code>command1 >> log_file 2>&1 </code></pre> <p>If you want different files:</p> <pre><code>command1 >> log_file 2>> err_file </code></pre> | 387, 4867, 19156, 26698 | bash, io-redirection, stderr, stdout | <h1>How to redirect both stdout and stderr to a file</h1>
<p>I am running a bash script that creates a log file for the execution of the command</p>
<p>I use the following</p>
<pre><code>Command1 >> log_file
Command2 >> log_file
</code></pre>
<p>This only sends the standard output and not the standard error... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 290 | bash | # How to redirect both stdout and stderr to a file
I am running a bash script that creates a log file for the execution of the command
I use the following
```
Command1 >> log_file
Command2 >> log_file
```
This only sends the standard output and not the standard error which appears on the terminal. | If you want to log to the same file:
```
command1 >> log_file 2>&1
```
If you want different files:
```
command1 >> log_file 2>> err_file
``` |
4143252 | How to make the 'cut' command treat same sequental delimiters as one? | 345 | 2010-11-10 10:04:15 | <p>I'm trying to extract a certain (the fourth) field from the column-based, 'space'-adjusted text stream. I'm trying to use the <code>cut</code> command in the following manner: </p>
<p><code>cat text.txt | cut -d " " -f 4</code></p>
<p>Unfortunately, <code>cut</code> doesn't treat several spaces as one delimiter. I... | 178,967 | 411,928 | 2024-11-21 10:30:22 | 4,483,833 | 602 | 2010-12-19 16:22:01 | 348,785 | 2018-04-23 23:03:23 | https://stackoverflow.com/q/4143252 | https://stackoverflow.com/a/4483833 | <p>Try:</p>
<pre><code>tr -s ' ' <text.txt | cut -d ' ' -f4
</code></pre>
<p>From the <code>tr</code> man page:</p>
<pre>
-s, --squeeze-repeats replace each input sequence of a repeated character
that is listed in SET1 with a single occurrence
of that character
</... | <p>Try:</p> <pre><code>tr -s ' ' <text.txt | cut -d ' ' -f4 </code></pre> <p>From the <code>tr</code> man page:</p> <pre> -s, --squeeze-repeats replace each input sequence of a repeated character that is listed in SET1 with a single occurrence of that character </... | 34, 387, 4257, 16168 | bash, cut, delimiter, unix | <h1>How to make the 'cut' command treat same sequental delimiters as one?</h1>
<p>I'm trying to extract a certain (the fourth) field from the column-based, 'space'-adjusted text stream. I'm trying to use the <code>cut</code> command in the following manner: </p>
<p><code>cat text.txt | cut -d " " -f 4</code></p>
<p>U... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 291 | bash | # How to make the 'cut' command treat same sequental delimiters as one?
I'm trying to extract a certain (the fourth) field from the column-based, 'space'-adjusted text stream. I'm trying to use the `cut` command in the following manner:
`cat text.txt | cut -d " " -f 4`
Unfortunately, `cut` doesn't treat several spac... | Try:
```
tr -s ' ' <text.txt | cut -d ' ' -f4
```
From the `tr` man page:
```
-s, --squeeze-repeats replace each input sequence of a repeated character
that is listed in SET1 with a single occurrence
of that character
``` |
5731234 | How can I get the start time of a long-running Linux process? | 403 | 2011-04-20 13:38:27 | <p>Is it possible to get the start time of an old running process? It seems that <code>ps</code> will report the date (not the time) if it wasn't started today, and only the year if it wasn't started this year. Is the precision lost forever for old processes?</p>
| 368,238 | 512,652 | 2024-12-19 07:30:42 | 5,731,337 | 600 | 2011-04-20 13:43:47 | 297,696 | 2018-05-21 16:40:32 | https://stackoverflow.com/q/5731234 | https://stackoverflow.com/a/5731337 | <p>You can specify a formatter and use <code>lstart</code>, like this command:</p>
<pre><code>ps -eo pid,lstart,cmd
</code></pre>
<p>The above command will output all processes, with formatters to get PID, command run, and date+time started.</p>
<p>Example (from Debian/Jessie command line)</p>
<pre><code>$ ps -eo p... | <p>You can specify a formatter and use <code>lstart</code>, like this command:</p> <pre><code>ps -eo pid,lstart,cmd </code></pre> <p>The above command will output all processes, with formatters to get PID, command run, and date+time started.</p> <p>Example (from Debian/Jessie command line)</p> <pre><code>$ ps -eo p... | 58, 387, 5910 | bash, linux, process | <h1>How can I get the start time of a long-running Linux process?</h1>
<p>Is it possible to get the start time of an old running process? It seems that <code>ps</code> will report the date (not the time) if it wasn't started today, and only the year if it wasn't started this year. Is the precision lost forever for old ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 292 | bash | # How can I get the start time of a long-running Linux process?
Is it possible to get the start time of an old running process? It seems that `ps` will report the date (not the time) if it wasn't started today, and only the year if it wasn't started this year. Is the precision lost forever for old processes? | You can specify a formatter and use `lstart`, like this command:
```
ps -eo pid,lstart,cmd
```
The above command will output all processes, with formatters to get PID, command run, and date+time started.
Example (from Debian/Jessie command line)
```
$ ps -eo pid,lstart,cmd
PID CMD ... |
2439579 | How to get the first line of a file in a bash script? | 392 | 2010-03-13 18:56:13 | <p>I have to put in a bash variable the first line of a file. I guess it is with the grep command, but it is any way to restrict the number of lines?</p>
| 586,502 | 288,247 | 2024-06-17 08:18:19 | 2,439,587 | 600 | 2010-03-13 18:58:06 | 56,338 | 2010-03-13 18:58:06 | https://stackoverflow.com/q/2439579 | https://stackoverflow.com/a/2439587 | <p><code>head</code> takes the first lines from a file, and the <code>-n</code> parameter can be used to specify how many lines should be extracted:</p>
<pre><code>line=$(head -n 1 filename)
</code></pre>
| <p><code>head</code> takes the first lines from a file, and the <code>-n</code> parameter can be used to specify how many lines should be extracted:</p> <pre><code>line=$(head -n 1 filename) </code></pre> | 387 | bash | <h1>How to get the first line of a file in a bash script?</h1>
<p>I have to put in a bash variable the first line of a file. I guess it is with the grep command, but it is any way to restrict the number of lines?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 293 | bash | # How to get the first line of a file in a bash script?
I have to put in a bash variable the first line of a file. I guess it is with the grep command, but it is any way to restrict the number of lines? | `head` takes the first lines from a file, and the `-n` parameter can be used to specify how many lines should be extracted:
```
line=$(head -n 1 filename)
``` |
11162406 | Open and write data to text file using Bash? | 375 | 2012-06-22 18:52:22 | <p>How can I write data to a text file automatically by shell scripting in Linux?</p>
<p>I was able to open the file. However, I don't know how to write data to it.</p>
| 1,056,480 | 1,055,090 | 2023-11-07 06:59:49 | 11,162,510 | 600 | 2012-06-22 18:59:35 | 428,916 | 2022-12-02 01:43:25 | https://stackoverflow.com/q/11162406 | https://stackoverflow.com/a/11162510 | <p>The short answer:</p>
<pre class="lang-bash prettyprint-override"><code>echo "some data for the file" >> fileName
</code></pre>
<p>However, <a href="https://unix.stackexchange.com/a/58312/364698"><code>echo</code> doesn't deal with end of line characters (EOFs) in an ideal way</a>. So, if you're goin... | <p>The short answer:</p> <pre class="lang-bash prettyprint-override"><code>echo "some data for the file" >> fileName </code></pre> <p>However, <a href="https://unix.stackexchange.com/a/58312/364698"><code>echo</code> doesn't deal with end of line characters (EOFs) in an ideal way</a>. So, if you're goin... | 387, 390 | bash, shell | <h1>Open and write data to text file using Bash?</h1>
<p>How can I write data to a text file automatically by shell scripting in Linux?</p>
<p>I was able to open the file. However, I don't know how to write data to it.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 294 | bash | # Open and write data to text file using Bash?
How can I write data to a text file automatically by shell scripting in Linux?
I was able to open the file. However, I don't know how to write data to it. | The short answer:
```
echo "some data for the file" >> fileName
```
However, [`echo` doesn't deal with end of line characters (EOFs) in an ideal way](https://unix.stackexchange.com/a/58312/364698). So, if you're going to append more than one line, do it with `printf`:
```
printf "some data for the file\nAnd a new li... |
183901 | How do I start PowerShell from Windows Explorer? | 312 | 2008-10-08 17:30:16 | <p>Is there a way to start PowerShell in a specific folder from Windows Explorer, e.g. to right-click in a folder and have an option like "Open PowerShell in this Folder"?</p>
<p>It's really annoying to have to change directories to my project folder the first time I run MSBuild every day.</p>
| 185,220 | 549 | 2024-11-20 00:16:38 | 6,599,296 | 600 | 2011-07-06 15:47:40 | 1,630 | 2017-05-28 23:21:34 | https://stackoverflow.com/q/183901 | https://stackoverflow.com/a/6599296 | <p>In Windows Explorer, just go to the Address Bar at the top (keyboard shortcuts: <kbd>Alt</kbd>+<kbd>D</kbd> or <kbd>Ctrl</kbd>+<kbd>L</kbd>) and type <code>powershell</code> or <code>powershell_ise</code> and press <kbd>Enter</kbd>. A PowerShell command window opens with the current directory.</p>
| <p>In Windows Explorer, just go to the Address Bar at the top (keyboard shortcuts: <kbd>Alt</kbd>+<kbd>D</kbd> or <kbd>Ctrl</kbd>+<kbd>L</kbd>) and type <code>powershell</code> or <code>powershell_ise</code> and press <kbd>Enter</kbd>. A PowerShell command window opens with the current directory.</p> | 64, 526 | powershell, windows | <h1>How do I start PowerShell from Windows Explorer?</h1>
<p>Is there a way to start PowerShell in a specific folder from Windows Explorer, e.g. to right-click in a folder and have an option like "Open PowerShell in this Folder"?</p>
<p>It's really annoying to have to change directories to my project folder the first ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 295 | bash | # How do I start PowerShell from Windows Explorer?
Is there a way to start PowerShell in a specific folder from Windows Explorer, e.g. to right-click in a folder and have an option like "Open PowerShell in this Folder"?
It's really annoying to have to change directories to my project folder the first time I run MSBui... | In Windows Explorer, just go to the Address Bar at the top (keyboard shortcuts: `Alt`+`D` or `Ctrl`+`L`) and type `powershell` or `powershell_ise` and press `Enter`. A PowerShell command window opens with the current directory. |
626533 | How can I ssh directly to a particular directory? | 365 | 2009-03-09 14:50:21 | <p>I often have to login to one of several servers and go to one of several directories on those machines. Currently I do something of this sort:</p>
<pre>
localhost ~]$ ssh somehost
Welcome to somehost!
somehost ~]$ cd /some/directory/somewhere/named/Foo
somehost Foo]$
</pre>
<p>I have scripts that can determine... | 339,613 | 7,476 | 2024-01-10 16:15:14 | 626,574 | 599 | 2009-03-09 14:59:05 | 28,388 | 2024-01-10 16:15:14 | https://stackoverflow.com/q/626533 | https://stackoverflow.com/a/626574 | <p>You can do the following:</p>
<pre><code>ssh -t xxx.xxx.xxx.xxx "cd /directory_wanted ; bash --login"
</code></pre>
<p>This way, you will get a login shell right on the directory_wanted.</p>
<hr />
<p>Explanation</p>
<blockquote>
<p><code>-t</code> Force pseudo-terminal allocation. This can be used to exe... | <p>You can do the following:</p> <pre><code>ssh -t xxx.xxx.xxx.xxx "cd /directory_wanted ; bash --login" </code></pre> <p>This way, you will get a login shell right on the directory_wanted.</p> <hr /> <p>Explanation</p> <blockquote> <p><code>-t</code> Force pseudo-terminal allocation. This can be used to exe... | 386, 387, 390, 531 | bash, scripting, shell, ssh | <h1>How can I ssh directly to a particular directory?</h1>
<p>I often have to login to one of several servers and go to one of several directories on those machines. Currently I do something of this sort:</p>
<pre>
localhost ~]$ ssh somehost
Welcome to somehost!
somehost ~]$ cd /some/directory/somewhere/named/Foo
s... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 296 | bash | # How can I ssh directly to a particular directory?
I often have to login to one of several servers and go to one of several directories on those machines. Currently I do something of this sort:
```
localhost ~]$ ssh somehost
Welcome to somehost!
somehost ~]$ cd /some/directory/somewhere/named/Foo
somehost Foo]$
``... | You can do the following:
```
ssh -t xxx.xxx.xxx.xxx "cd /directory_wanted ; bash --login"
```
This way, you will get a login shell right on the directory_wanted.
---
Explanation
> `-t` Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be v... |
25373188 | How to place the ~/.composer/vendor/bin directory in your PATH? | 276 | 2014-08-18 22:44:43 | <p>I'm on Ubuntu 14.04 and I've been trying all possible methods to install Laravel to no avail. Error messages everything I try. I'm now trying the first method in the quickstart documentation, that is, via Laravel Installer, but it says to "Make sure to place the <code>~/.composer/vendor/bin</code> directory in your ... | 331,160 | 2,827,463 | 2022-08-29 11:55:46 | 25,373,254 | 599 | 2014-08-18 22:51:30 | 3,906,760 | 2018-09-03 07:25:26 | https://stackoverflow.com/q/25373188 | https://stackoverflow.com/a/25373254 | <p>To put this folder on the PATH environment variable type</p>
<pre><code>export PATH="$PATH:$HOME/.composer/vendor/bin"
</code></pre>
<p>This appends the folder to your existing PATH, however, it is only active for your current terminal session.</p>
<p>If you want it to be automatically set, it depends on the shel... | <p>To put this folder on the PATH environment variable type</p> <pre><code>export PATH="$PATH:$HOME/.composer/vendor/bin" </code></pre> <p>This appends the folder to your existing PATH, however, it is only active for your current terminal session.</p> <p>If you want it to be automatically set, it depends on the shel... | 218, 387, 549, 6268, 75151 | bash, directory, laravel, path, ubuntu | <h1>How to place the ~/.composer/vendor/bin directory in your PATH?</h1>
<p>I'm on Ubuntu 14.04 and I've been trying all possible methods to install Laravel to no avail. Error messages everything I try. I'm now trying the first method in the quickstart documentation, that is, via Laravel Installer, but it says to "Make... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 297 | bash | # How to place the ~/.composer/vendor/bin directory in your PATH?
I'm on Ubuntu 14.04 and I've been trying all possible methods to install Laravel to no avail. Error messages everything I try. I'm now trying the first method in the quickstart documentation, that is, via Laravel Installer, but it says to "Make sure to ... | To put this folder on the PATH environment variable type
```
export PATH="$PATH:$HOME/.composer/vendor/bin"
```
This appends the folder to your existing PATH, however, it is only active for your current terminal session.
If you want it to be automatically set, it depends on the shell you are using. For bash, you can... |
805418 | How can I find encoding of a file via a script on Linux? | 447 | 2009-04-30 05:13:48 | <p>I need to find the encoding of all files that are placed in a directory. <br />
Is there a way to find the encoding used?</p>
<p>The <a href="https://linux.die.net/man/1/file" rel="noreferrer"><code>file</code></a> command is not able to do this.</p>
<p>The encoding of interest to me is <a href="https://en.wikipedia... | 740,005 | 64,833 | 2024-11-08 01:59:42 | 805,474 | 594 | 2009-04-30 05:41:58 | 54,491 | 2021-05-28 23:34:59 | https://stackoverflow.com/q/805418 | https://stackoverflow.com/a/805474 | <p>It sounds like you're looking for <code>enca</code>. It can guess and even convert between encodings. Just look at the <a href="http://linux.die.net/man/1/enconv" rel="noreferrer">man page</a>.</p>
<p>Or, failing that, use <code>file -i</code> (Linux) or <code>file -I</code> (OS X). That will output MIME-type inform... | <p>It sounds like you're looking for <code>enca</code>. It can guess and even convert between encodings. Just look at the <a href="http://linux.die.net/man/1/enconv" rel="noreferrer">man page</a>.</p> <p>Or, failing that, use <code>file -i</code> (Linux) or <code>file -I</code> (OS X). That will output MIME-type inform... | 34, 390, 1124, 5310 | encoding, file, shell, unix | <h1>How can I find encoding of a file via a script on Linux?</h1>
<p>I need to find the encoding of all files that are placed in a directory. <br />
Is there a way to find the encoding used?</p>
<p>The <a href="https://linux.die.net/man/1/file" rel="noreferrer"><code>file</code></a> command is not able to do this.</p>
... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 298 | bash | # How can I find encoding of a file via a script on Linux?
I need to find the encoding of all files that are placed in a directory.
Is there a way to find the encoding used?
The [`file`](https://linux.die.net/man/1/file) command is not able to do this.
The encoding of interest to me is [ISO 8859-1](https://en.wik... | It sounds like you're looking for `enca`. It can guess and even convert between encodings. Just look at the [man page](http://linux.die.net/man/1/enconv).
Or, failing that, use `file -i` (Linux) or `file -I` (OS X). That will output MIME-type information for the file, which will also include the character-set encoding... |
5349718 | How can I repeat a character in Bash? | 378 | 2011-03-18 08:45:42 | <p>How could I do this with <code>echo</code>?</p>
<pre class="lang-sh prettyprint-override"><code>perl -E 'say "=" x 100'
</code></pre>
| 276,214 | 198,183 | 2025-10-31 17:30:42 | 5,349,842 | 593 | 2011-03-18 08:58:47 | 7,412 | 2024-09-16 11:12:31 | https://stackoverflow.com/q/5349718 | https://stackoverflow.com/a/5349842 | <p>You can use:</p>
<pre class="lang-bash prettyprint-override"><code>printf '=%.0s' {1..100}
</code></pre>
<p>How this works:</p>
<p>Bash expands <code>{1..100}</code> so the command becomes:</p>
<pre class="lang-bash prettyprint-override"><code>printf '=%.0s' 1 2 3 4 ... 100
</code></pre>
<p>I've set printf's format ... | <p>You can use:</p> <pre class="lang-bash prettyprint-override"><code>printf '=%.0s' {1..100} </code></pre> <p>How this works:</p> <p>Bash expands <code>{1..100}</code> so the command becomes:</p> <pre class="lang-bash prettyprint-override"><code>printf '=%.0s' 1 2 3 4 ... 100 </code></pre> <p>I've set printf's format ... | 387, 390, 13824 | bash, echo, shell | <h1>How can I repeat a character in Bash?</h1>
<p>How could I do this with <code>echo</code>?</p>
<pre class="lang-sh prettyprint-override"><code>perl -E 'say "=" x 100'
</code></pre>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 299 | bash | # How can I repeat a character in Bash?
How could I do this with `echo`?
```
perl -E 'say "=" x 100'
``` | You can use:
```
printf '=%.0s' {1..100}
```
How this works:
Bash expands `{1..100}` so the command becomes:
```
printf '=%.0s' 1 2 3 4 ... 100
```
I've set printf's format to `=%.0s` which means that it will always print a single `=` no matter what argument it is given. Therefore it prints 100 `=`s.
NB: To print... |
9727695 | if arguments is equal to this string, define a variable like this string | 345 | 2012-03-15 20:31:29 | <p>I am doing some bash script and now I got one variable call <code>source</code> and one array called <code>samples</code>, like this:</p>
<pre><code>source='country'
samples=(US Canada Mexico...)
</code></pre>
<p>as I want to expand the number of sources (and each source has its own samples) I tried to add some ar... | 649,777 | 804,184 | 2022-12-24 20:26:35 | 9,727,942 | 593 | 2012-03-15 20:48:58 | 1,268,429 | 2012-03-15 20:48:58 | https://stackoverflow.com/q/9727695 | https://stackoverflow.com/a/9727942 | <p>Don't forget about spaces:</p>
<pre><code>source=""
samples=("")
if [ $1 = "country" ]; then
source="country"
samples="US Canada Mexico..."
else
echo "try again"
fi
</code></pre>
| <p>Don't forget about spaces:</p> <pre><code>source="" samples=("") if [ $1 = "country" ]; then source="country" samples="US Canada Mexico..." else echo "try again" fi </code></pre> | 387, 531, 2313 | arguments, bash, scripting | <h1>if arguments is equal to this string, define a variable like this string</h1>
<p>I am doing some bash script and now I got one variable call <code>source</code> and one array called <code>samples</code>, like this:</p>
<pre><code>source='country'
samples=(US Canada Mexico...)
</code></pre>
<p>as I want to expand ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 300 | bash | # if arguments is equal to this string, define a variable like this string
I am doing some bash script and now I got one variable call `source` and one array called `samples`, like this:
```
source='country'
samples=(US Canada Mexico...)
```
as I want to expand the number of sources (and each source has its own samp... | Don't forget about spaces:
```
source=""
samples=("")
if [ $1 = "country" ]; then
source="country"
samples="US Canada Mexico..."
else
echo "try again"
fi
``` |
1489277 | How to use '-prune' option of 'find' in sh? | 293 | 2009-09-28 20:47:00 | <p>I don't quite understand the example given from the <code>man find</code>, can anyone give me some examples and explanations? Can I combine regular expression in it? </p>
<hr>
<p>The more detailed question is like this: </p>
<p>Write a shell script, <code>changeall</code>, which has an interface like <code>change... | 167,190 | 115,622 | 2021-12-30 14:50:54 | 1,489,405 | 593 | 2009-09-28 21:12:49 | 90,848 | 2020-09-13 12:55:15 | https://stackoverflow.com/q/1489277 | https://stackoverflow.com/a/1489405 | <p>The thing I'd found confusing about <code>-prune</code> is that it's an action (like <code>-print</code>), not a test (like <code>-name</code>). It alters the "to-do" list, <em>but always returns true</em>.</p>
<p>The general pattern for using <code>-prune</code> is this:</p>
<pre><code>find [path] [condit... | <p>The thing I'd found confusing about <code>-prune</code> is that it's an action (like <code>-print</code>), not a test (like <code>-name</code>). It alters the "to-do" list, <em>but always returns true</em>.</p> <p>The general pattern for using <code>-prune</code> is this:</p> <pre><code>find [path] [condit... | 18, 390, 10193, 10720 | find, manual, regex, shell | <h1>How to use '-prune' option of 'find' in sh?</h1>
<p>I don't quite understand the example given from the <code>man find</code>, can anyone give me some examples and explanations? Can I combine regular expression in it? </p>
<hr>
<p>The more detailed question is like this: </p>
<p>Write a shell script, <code>chang... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 301 | bash | # How to use '-prune' option of 'find' in sh?
I don't quite understand the example given from the `man find`, can anyone give me some examples and explanations? Can I combine regular expression in it?
---
The more detailed question is like this:
Write a shell script, `changeall`, which has an interface like `change... | The thing I'd found confusing about `-prune` is that it's an action (like `-print`), not a test (like `-name`). It alters the "to-do" list, *but always returns true*.
The general pattern for using `-prune` is this:
```
find [path] [conditions to prune] -prune -o \
[your usual conditions] [actions to perfo... |
385408 | Get program execution time in the shell | 465 | 2008-12-22 02:27:41 | <p>I want to execute something in a linux shell under a few different conditions, and be able to output the execution time of each execution.</p>
<p>I know I could write a perl or python script that would do this, but is there a way I can do it in the shell? (which happens to be bash)</p>
| 521,018 | 41,613 | 2022-12-18 21:36:46 | 385,418 | 592 | 2008-12-22 02:31:17 | 25,222 | 2016-10-30 03:52:23 | https://stackoverflow.com/q/385408 | https://stackoverflow.com/a/385418 | <p>Use the built-in <code>time</code> keyword:</p>
<pre>
$ help time
time: time [-p] PIPELINE
Execute PIPELINE and print a summary of the real time, user CPU time,
and system CPU time spent executing PIPELINE when it terminates.
The return status is the return status of PIPELINE. The `-p' option
prin... | <p>Use the built-in <code>time</code> keyword:</p> <pre> $ help time time: time [-p] PIPELINE Execute PIPELINE and print a summary of the real time, user CPU time, and system CPU time spent executing PIPELINE when it terminates. The return status is the return status of PIPELINE. The `-p' option prin... | 58, 387, 390 | bash, linux, shell | <h1>Get program execution time in the shell</h1>
<p>I want to execute something in a linux shell under a few different conditions, and be able to output the execution time of each execution.</p>
<p>I know I could write a perl or python script that would do this, but is there a way I can do it in the shell? (which happ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 302 | bash | # Get program execution time in the shell
I want to execute something in a linux shell under a few different conditions, and be able to output the execution time of each execution.
I know I could write a perl or python script that would do this, but is there a way I can do it in the shell? (which happens to be bash) | Use the built-in `time` keyword:
```
$ help time
time: time [-p] PIPELINE
Execute PIPELINE and print a summary of the real time, user CPU time,
and system CPU time spent executing PIPELINE when it terminates.
The return status is the return status of PIPELINE. The `-p' option
prints the timing summar... |
16034749 | if, elif, else statement issues in Bash | 463 | 2013-04-16 10:30:37 | <p>I can't seem to work out what the issue with the following <code>if</code> statement is in regards to the <code>elif</code> and <code>then</code>. Keep in mind the <code>printf</code> is still under development I just haven't been able to test it yet in the statement so is more than likely wrong.</p>
<p>The error I... | 958,636 | 507,313 | 2021-10-21 03:34:38 | 16,034,814 | 589 | 2013-04-16 10:34:25 | 1,983,854 | 2021-10-21 03:34:38 | https://stackoverflow.com/q/16034749 | https://stackoverflow.com/a/16034814 | <p>There is a space missing between <code>elif</code> and <code>[</code>:</p>
<pre><code>elif[ "$seconds" -gt 0 ]
</code></pre>
<p>should be</p>
<pre><code>elif [ "$seconds" -gt 0 ]
</code></pre>
<p>All together, the syntax to follow is:</p>
<pre><code>if [ conditions ]; then
# Things
elif [ othe... | <p>There is a space missing between <code>elif</code> and <code>[</code>:</p> <pre><code>elif[ "$seconds" -gt 0 ] </code></pre> <p>should be</p> <pre><code>elif [ "$seconds" -gt 0 ] </code></pre> <p>All together, the syntax to follow is:</p> <pre><code>if [ conditions ]; then # Things elif [ othe... | 387, 2773 | bash, if-statement | <h1>if, elif, else statement issues in Bash</h1>
<p>I can't seem to work out what the issue with the following <code>if</code> statement is in regards to the <code>elif</code> and <code>then</code>. Keep in mind the <code>printf</code> is still under development I just haven't been able to test it yet in the statement ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 303 | bash | # if, elif, else statement issues in Bash
I can't seem to work out what the issue with the following `if` statement is in regards to the `elif` and `then`. Keep in mind the `printf` is still under development I just haven't been able to test it yet in the statement so is more than likely wrong.
The error I'm getting ... | There is a space missing between `elif` and `[`:
```
elif[ "$seconds" -gt 0 ]
```
should be
```
elif [ "$seconds" -gt 0 ]
```
All together, the syntax to follow is:
```
if [ conditions ]; then
# Things
elif [ other_conditions ]; then
# Other things
else
# In case none of the above occurs
fi
```
---
As I... |
17144355 | How can I replace every occurrence of a String in a file with PowerShell? | 402 | 2013-06-17 09:29:35 | <p>Using PowerShell, I want to replace all exact occurrences of <code>[MYID]</code> in a given file with <code>MyValue</code>. What is the easiest way to do so?</p>
| 635,295 | 373,674 | 2025-03-28 18:43:28 | 17,144,445 | 589 | 2013-06-17 09:35:15 | 381,149 | 2023-10-23 12:43:50 | https://stackoverflow.com/q/17144355 | https://stackoverflow.com/a/17144445 | <p>Use (V3 version):</p>
<pre><code>(Get-Content c:\temp\test.txt).Replace('[MYID]', 'MyValue') | Set-Content c:\temp\test.txt
</code></pre>
<p>Or for V2:</p>
<pre><code>(Get-Content c:\temp\test.txt) -replace '\[MYID\]', 'MyValue' | Set-Content c:\temp\test.txt
</code></pre>
| <p>Use (V3 version):</p> <pre><code>(Get-Content c:\temp\test.txt).Replace('[MYID]', 'MyValue') | Set-Content c:\temp\test.txt </code></pre> <p>Or for V2:</p> <pre><code>(Get-Content c:\temp\test.txt) -replace '\[MYID\]', 'MyValue' | Set-Content c:\temp\test.txt </code></pre> | 526 | powershell | <h1>How can I replace every occurrence of a String in a file with PowerShell?</h1>
<p>Using PowerShell, I want to replace all exact occurrences of <code>[MYID]</code> in a given file with <code>MyValue</code>. What is the easiest way to do so?</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 304 | bash | # How can I replace every occurrence of a String in a file with PowerShell?
Using PowerShell, I want to replace all exact occurrences of `[MYID]` in a given file with `MyValue`. What is the easiest way to do so? | Use (V3 version):
```
(Get-Content c:\temp\test.txt).Replace('[MYID]', 'MyValue') | Set-Content c:\temp\test.txt
```
Or for V2:
```
(Get-Content c:\temp\test.txt) -replace '\[MYID\]', 'MyValue' | Set-Content c:\temp\test.txt
``` |
6958689 | Running multiple commands with xargs | 464 | 2011-08-05 15:22:14 | <pre><code>cat a.txt | xargs -I % echo %
</code></pre>
<p>In the example above, <code>xargs</code> takes <code>echo %</code> as the command argument. But in some cases, I need multiple commands to process the argument instead of one. For example:</p>
<pre><code>cat a.txt | xargs -I % {command1; command2; ... }
</code><... | 304,228 | 404,264 | 2025-08-11 03:11:38 | 6,958,957 | 586 | 2011-08-05 15:41:33 | 827,263 | 2019-10-01 01:50:32 | https://stackoverflow.com/q/6958689 | https://stackoverflow.com/a/6958957 | <pre><code>cat a.txt | xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _
</code></pre>
<p>...or, without a <a href="http://www.catb.org/jargon/html/U/UUOC.html" rel="noreferrer">Useless Use Of cat</a>:</p>
<pre><code><a.txt xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$... | <pre><code>cat a.txt | xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _ </code></pre> <p>...or, without a <a href="http://www.catb.org/jargon/html/U/UUOC.html" rel="noreferrer">Useless Use Of cat</a>:</p> <pre><code><a.txt xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$... | 387, 10326 | bash, xargs | <h1>Running multiple commands with xargs</h1>
<pre><code>cat a.txt | xargs -I % echo %
</code></pre>
<p>In the example above, <code>xargs</code> takes <code>echo %</code> as the command argument. But in some cases, I need multiple commands to process the argument instead of one. For example:</p>
<pre><code>cat a.txt | ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 305 | bash | # Running multiple commands with xargs
```
cat a.txt | xargs -I % echo %
```
In the example above, `xargs` takes `echo %` as the command argument. But in some cases, I need multiple commands to process the argument instead of one. For example:
```
cat a.txt | xargs -I % {command1; command2; ... }
```
But `xargs` do... | ```
cat a.txt | xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _
```
...or, without a [Useless Use Of cat](http://www.catb.org/jargon/html/U/UUOC.html):
```
<a.txt xargs -d $'\n' sh -c 'for arg do command1 "$arg"; command2 "$arg"; ...; done' _
```
---
To explain some of the finer poin... |
5274294 | How can you run a command in bash over and over until success? | 372 | 2011-03-11 14:41:26 | <p>I have a script and want to ask the user for some information, but the script cannot continue until the user fills in this information. The following is my attempt at putting a command into a loop to achieve this but it doesn't work for some reason:</p>
<pre class="lang-sh prettyprint-override"><code>echo "Plea... | 246,498 | 506,962 | 2024-11-15 03:06:11 | 5,274,386 | 583 | 2011-03-11 14:48:26 | 616,700 | 2020-05-11 16:19:47 | https://stackoverflow.com/q/5274294 | https://stackoverflow.com/a/5274386 | <pre><code>until passwd
do
echo "Try again"
done
</code></pre>
<p>or</p>
<pre><code>while ! passwd
do
echo "Try again"
done
</code></pre>
| <pre><code>until passwd do echo "Try again" done </code></pre> <p>or</p> <pre><code>while ! passwd do echo "Try again" done </code></pre> | 387, 1796, 17310 | bash, command, while-loop | <h1>How can you run a command in bash over and over until success?</h1>
<p>I have a script and want to ask the user for some information, but the script cannot continue until the user fills in this information. The following is my attempt at putting a command into a loop to achieve this but it doesn't work for some rea... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 306 | bash | # How can you run a command in bash over and over until success?
I have a script and want to ask the user for some information, but the script cannot continue until the user fills in this information. The following is my attempt at putting a command into a loop to achieve this but it doesn't work for some reason:
```... | ```
until passwd
do
echo "Try again"
done
```
or
```
while ! passwd
do
echo "Try again"
done
``` |
618378 | Select unique or distinct values from a list in UNIX shell script | 333 | 2009-03-06 10:33:38 | <p>I have a ksh script that returns a long list of values, newline separated, and I want to see only the unique/distinct values. It is possible to do this?</p>
<p>For example, say my output is file suffixes in a directory:</p>
<blockquote>
<pre><code>tar
gz
java
gz
java
tar
class
class
</code></pre>
</blockquote>
<p... | 443,681 | 2,362 | 2021-08-28 06:16:02 | 618,381 | 581 | 2009-03-06 10:34:51 | 15,537 | 2009-03-06 10:48:23 | https://stackoverflow.com/q/618378 | https://stackoverflow.com/a/618381 | <p>You might want to look at the <code>uniq</code> and <code>sort</code> applications.</p>
<pre>
./yourscript.ksh | sort | uniq
</pre>
<p>(FYI, yes, the sort is necessary in this command line, <code>uniq</code> only strips duplicate lines that are immediately after each other)</p>
<p><strong>EDIT:</strong></p>
<p>C... | <p>You might want to look at the <code>uniq</code> and <code>sort</code> applications.</p> <pre> ./yourscript.ksh | sort | uniq </pre> <p>(FYI, yes, the sort is necessary in this command line, <code>uniq</code> only strips duplicate lines that are immediately after each other)</p> <p><strong>EDIT:</strong></p> <p>C... | 387, 1964, 6205, 9525, 10327 | bash, distinct, ksh, sh, unique | <h1>Select unique or distinct values from a list in UNIX shell script</h1>
<p>I have a ksh script that returns a long list of values, newline separated, and I want to see only the unique/distinct values. It is possible to do this?</p>
<p>For example, say my output is file suffixes in a directory:</p>
<blockquote>
<pr... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 307 | bash | # Select unique or distinct values from a list in UNIX shell script
I have a ksh script that returns a long list of values, newline separated, and I want to see only the unique/distinct values. It is possible to do this?
For example, say my output is file suffixes in a directory:
> ```
> tar
> gz
> java
> gz
> java
... | You might want to look at the `uniq` and `sort` applications.
```
./yourscript.ksh | sort | uniq
```
(FYI, yes, the sort is necessary in this command line, `uniq` only strips duplicate lines that are immediately after each other)
**EDIT:**
Contrary to what has been posted by [Aaron Digulla](https://stackoverflow.co... |
8967902 | Why do you need to put #!/bin/bash at the beginning of a script file? | 707 | 2012-01-23 06:24:31 | <p>I have made <a href="http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="noreferrer">Bash</a> scripts before and they all ran fine without <code>#!/bin/bash</code> at the beginning.</p>
<p>What's the point of putting it in? Would things be any different?</p>
<p>Also, how do you pronounce <code>#</code>? I kno... | 961,878 | 404,020 | 2024-04-03 14:57:59 | 8,967,916 | 578 | 2012-01-23 06:26:04 | 421,195 | 2017-09-26 17:00:30 | https://stackoverflow.com/q/8967902 | https://stackoverflow.com/a/8967916 | <p>It's a convention so the *nix shell knows what kind of interpreter to run.</p>
<p>For example, older flavors of ATT defaulted to <em>sh</em> (the Bourne shell), while older versions of BSD defaulted to <em>csh</em> (the C shell).</p>
<p>Even today (where most systems run bash, the <em>"Bourne Again Shell"</em>), s... | <p>It's a convention so the *nix shell knows what kind of interpreter to run.</p> <p>For example, older flavors of ATT defaulted to <em>sh</em> (the Bourne shell), while older versions of BSD defaulted to <em>csh</em> (the C shell).</p> <p>Even today (where most systems run bash, the <em>"Bourne Again Shell"</em>), s... | 58, 387, 531, 8780 | bash, linux, scripting, shebang | <h1>Why do you need to put #!/bin/bash at the beginning of a script file?</h1>
<p>I have made <a href="http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29" rel="noreferrer">Bash</a> scripts before and they all ran fine without <code>#!/bin/bash</code> at the beginning.</p>
<p>What's the point of putting it in? Would th... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 308 | bash | # Why do you need to put #!/bin/bash at the beginning of a script file?
I have made [Bash](http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29) scripts before and they all ran fine without `#!/bin/bash` at the beginning.
What's the point of putting it in? Would things be any different?
Also, how do you pronounce `#`?... | It's a convention so the *nix shell knows what kind of interpreter to run.
For example, older flavors of ATT defaulted to *sh* (the Bourne shell), while older versions of BSD defaulted to *csh* (the C shell).
Even today (where most systems run bash, the *"Bourne Again Shell"*), scripts can be in bash, python, perl, r... |
4837673 | How to execute mongo commands through shell scripts? | 505 | 2011-01-29 15:26:01 | <p>I want to execute <code>mongo</code> commands in shell script, e.g. in a script <code>test.sh</code>:</p>
<pre><code>#!/bin/sh
mongo myDbName
db.mycollection.findOne()
show collections
</code></pre>
<p>When I execute this script via <code>./test.sh</code>, then the connection to MongoDB is established, but the fol... | 541,000 | 297,907 | 2023-10-19 06:12:27 | 6,000,360 | 578 | 2011-05-14 07:12:33 | 174,936 | 2019-05-24 10:52:42 | https://stackoverflow.com/q/4837673 | https://stackoverflow.com/a/6000360 | <p>You can also evaluate a command using the <code>--eval</code> flag, if it is just a single command.</p>
<pre><code>mongo --eval "printjson(db.serverStatus())"
</code></pre>
<p><strong>Please note:</strong> if you are using Mongo operators, starting with a $ sign, you'll want to surround the eval argument in single... | <p>You can also evaluate a command using the <code>--eval</code> flag, if it is just a single command.</p> <pre><code>mongo --eval "printjson(db.serverStatus())" </code></pre> <p><strong>Please note:</strong> if you are using Mongo operators, starting with a $ sign, you'll want to surround the eval argument in single... | 387, 390, 10327, 30073 | bash, mongodb, sh, shell | <h1>How to execute mongo commands through shell scripts?</h1>
<p>I want to execute <code>mongo</code> commands in shell script, e.g. in a script <code>test.sh</code>:</p>
<pre><code>#!/bin/sh
mongo myDbName
db.mycollection.findOne()
show collections
</code></pre>
<p>When I execute this script via <code>./test.sh</cod... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 309 | bash | # How to execute mongo commands through shell scripts?
I want to execute `mongo` commands in shell script, e.g. in a script `test.sh`:
```
#!/bin/sh
mongo myDbName
db.mycollection.findOne()
show collections
```
When I execute this script via `./test.sh`, then the connection to MongoDB is established, but the followi... | You can also evaluate a command using the `--eval` flag, if it is just a single command.
```
mongo --eval "printjson(db.serverStatus())"
```
**Please note:** if you are using Mongo operators, starting with a $ sign, you'll want to surround the eval argument in single quotes to keep the shell from evaluating the opera... |
22101778 | How to preserve line breaks when storing command output to a variable? | 307 | 2014-02-28 17:22:16 | <p>I’m using bash shell on Linux. I have this simple script …</p>
<pre><code>#!/bin/bash
TEMP=`sed -n '/'"Starting deployment of"'/,/'"Failed to start context"'/p' "/usr/java/jboss/standalone/log/server.log" | tac | awk '/'"Starting deployment of"'/ {print;exit} 1' | tac`
echo $TEMP
</code></pre>
<p>However, when I... | 162,335 | 1,235,929 | 2023-08-09 21:17:55 | 22,101,842 | 575 | 2014-02-28 17:25:31 | 970,195 | 2023-08-09 21:17:55 | https://stackoverflow.com/q/22101778 | https://stackoverflow.com/a/22101842 | <p>With shell scripting, one needs to always <strong>quote</strong> variables, especially when working with strings.</p>
<p>Here is an example of the problem:</p>
<p><em>Example variable:</em></p>
<pre><code>$ f="fafafda
> adffd
> adfadf
> adfafd
> afd"
</code></pre>
<p><strong>Output without quot... | <p>With shell scripting, one needs to always <strong>quote</strong> variables, especially when working with strings.</p> <p>Here is an example of the problem:</p> <p><em>Example variable:</em></p> <pre><code>$ f="fafafda > adffd > adfadf > adfafd > afd" </code></pre> <p><strong>Output without quot... | 58, 387, 390, 9313 | bash, line-breaks, linux, shell | <h1>How to preserve line breaks when storing command output to a variable?</h1>
<p>I’m using bash shell on Linux. I have this simple script …</p>
<pre><code>#!/bin/bash
TEMP=`sed -n '/'"Starting deployment of"'/,/'"Failed to start context"'/p' "/usr/java/jboss/standalone/log/server.log" | tac | awk '/'"Starting depl... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 310 | bash | # How to preserve line breaks when storing command output to a variable?
I’m using bash shell on Linux. I have this simple script …
```
#!/bin/bash
TEMP=`sed -n '/'"Starting deployment of"'/,/'"Failed to start context"'/p' "/usr/java/jboss/standalone/log/server.log" | tac | awk '/'"Starting deployment of"'/ {print;e... | With shell scripting, one needs to always **quote** variables, especially when working with strings.
Here is an example of the problem:
*Example variable:*
```
$ f="fafafda
> adffd
> adfadf
> adfafd
> afd"
```
**Output without quoting the variable:**
```
$ echo $f
fafafda adffd adfadf adfafd afd
```
**Output WITH... |
3224878 | What is the purpose of the : (colon) GNU Bash builtin? | 488 | 2010-07-11 22:30:25 | <p>What is the purpose of a command that does nothing, being little more than a comment leader, but is actually a shell builtin in and of itself?</p>
<p>It's slower than inserting a comment into your scripts by about 40% per call, which probably varies greatly depending on the size of the comment. The only possible rea... | 210,397 | 237,955 | 2025-03-18 07:04:41 | 3,224,910 | 574 | 2010-07-11 22:42:16 | 135,724 | 2015-06-04 23:52:28 | https://stackoverflow.com/q/3224878 | https://stackoverflow.com/a/3224910 | <p><strong>Historically</strong>, Bourne shells didn't have <code>true</code> and <code>false</code> as built-in commands. <code>true</code> was instead simply aliased to <code>:</code>, and <code>false</code> to something like <code>let 0</code>.</p>
<p><code>:</code> is slightly better than <code>true</code> for por... | <p><strong>Historically</strong>, Bourne shells didn't have <code>true</code> and <code>false</code> as built-in commands. <code>true</code> was instead simply aliased to <code>:</code>, and <code>false</code> to something like <code>let 0</code>.</p> <p><code>:</code> is slightly better than <code>true</code> for por... | 387, 390, 14334 | bash, built-in, shell | <h1>What is the purpose of the : (colon) GNU Bash builtin?</h1>
<p>What is the purpose of a command that does nothing, being little more than a comment leader, but is actually a shell builtin in and of itself?</p>
<p>It's slower than inserting a comment into your scripts by about 40% per call, which probably varies gre... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 311 | bash | # What is the purpose of the : (colon) GNU Bash builtin?
What is the purpose of a command that does nothing, being little more than a comment leader, but is actually a shell builtin in and of itself?
It's slower than inserting a comment into your scripts by about 40% per call, which probably varies greatly depending ... | **Historically**, Bourne shells didn't have `true` and `false` as built-in commands. `true` was instead simply aliased to `:`, and `false` to something like `let 0`.
`:` is slightly better than `true` for portability to ancient Bourne-derived shells. As a simple example, consider having neither the `!` pipeline operat... |
2871181 | Replacing some characters in a string with another character | 498 | 2010-05-20 05:18:39 | <p>I have a string like <code>AxxBCyyyDEFzzLMN</code> and I want to replace all the occurrences of <code>x</code>, <code>y</code>, and <code>z</code> with <code>_</code>.</p>
<p>How can I achieve this?</p>
<p>I know that <code>echo "$string" | tr 'x' '_' | tr 'y' '_'</code> would work, but I want to do that i... | 944,193 | 302,351 | 2022-09-01 15:46:29 | 2,871,217 | 573 | 2010-05-20 05:27:28 | 329,467 | 2014-08-23 23:29:48 | https://stackoverflow.com/q/2871181 | https://stackoverflow.com/a/2871217 | <pre><code>echo "$string" | tr xyz _
</code></pre>
<p>would replace each occurrence of <code>x</code>, <code>y</code>, or <code>z</code> with <code>_</code>, giving <code>A__BC___DEF__LMN</code> in your example.</p>
<pre><code>echo "$string" | sed -r 's/[xyz]+/_/g'
</code></pre>
<p>would replace repeating occurrence... | <pre><code>echo "$string" | tr xyz _ </code></pre> <p>would replace each occurrence of <code>x</code>, <code>y</code>, or <code>z</code> with <code>_</code>, giving <code>A__BC___DEF__LMN</code> in your example.</p> <pre><code>echo "$string" | sed -r 's/[xyz]+/_/g' </code></pre> <p>would replace repeating occurrence... | 139, 387 | bash, string | <h1>Replacing some characters in a string with another character</h1>
<p>I have a string like <code>AxxBCyyyDEFzzLMN</code> and I want to replace all the occurrences of <code>x</code>, <code>y</code>, and <code>z</code> with <code>_</code>.</p>
<p>How can I achieve this?</p>
<p>I know that <code>echo "$string"... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 312 | bash | # Replacing some characters in a string with another character
I have a string like `AxxBCyyyDEFzzLMN` and I want to replace all the occurrences of `x`, `y`, and `z` with `_`.
How can I achieve this?
I know that `echo "$string" | tr 'x' '_' | tr 'y' '_'` would work, but I want to do that in one go, without using pip... | ```
echo "$string" | tr xyz _
```
would replace each occurrence of `x`, `y`, or `z` with `_`, giving `A__BC___DEF__LMN` in your example.
```
echo "$string" | sed -r 's/[xyz]+/_/g'
```
would replace repeating occurrences of `x`, `y`, or `z` with a single `_`, giving `A_BC_DEF_LMN` in your example. |
3822621 | How to exit if a command failed? | 315 | 2010-09-29 14:32:37 | <p>I am a noob in shell-scripting. I want to print a message and exit my script if a command fails. I've tried:</p>
<pre><code>my_command && (echo 'my_command failed; exit)
</code></pre>
<p>but it does not work. It keeps executing the instructions following this line in the script. I'm using Ubuntu and bash.<... | 260,904 | 459,246 | 2022-07-10 11:07:14 | 3,822,649 | 573 | 2010-09-29 14:35:17 | 227,665 | 2013-01-30 17:16:31 | https://stackoverflow.com/q/3822621 | https://stackoverflow.com/a/3822649 | <p>Try:</p>
<pre><code>my_command || { echo 'my_command failed' ; exit 1; }
</code></pre>
<p>Four changes:</p>
<ul>
<li>Change <code>&&</code> to <code>||</code></li>
<li>Use <code>{ }</code> in place of <code>( )</code></li>
<li>Introduce <code>;</code> after <code>exit</code> and</li>
<li>spaces after <cod... | <p>Try:</p> <pre><code>my_command || { echo 'my_command failed' ; exit 1; } </code></pre> <p>Four changes:</p> <ul> <li>Change <code>&&</code> to <code>||</code></li> <li>Use <code>{ }</code> in place of <code>( )</code></li> <li>Introduce <code>;</code> after <code>exit</code> and</li> <li>spaces after <cod... | 58, 387, 10871, 54576 | bash, exit, exitstatus, linux | <h1>How to exit if a command failed?</h1>
<p>I am a noob in shell-scripting. I want to print a message and exit my script if a command fails. I've tried:</p>
<pre><code>my_command && (echo 'my_command failed; exit)
</code></pre>
<p>but it does not work. It keeps executing the instructions following this line ... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 313 | bash | # How to exit if a command failed?
I am a noob in shell-scripting. I want to print a message and exit my script if a command fails. I've tried:
```
my_command && (echo 'my_command failed; exit)
```
but it does not work. It keeps executing the instructions following this line in the script. I'm using Ubuntu and bash. | Try:
```
my_command || { echo 'my_command failed' ; exit 1; }
```
Four changes:
- Change `&&` to `||`
- Use `{ }` in place of `( )`
- Introduce `;` after `exit` and
- spaces after `{` and before `}`
Since you want to print the message and exit only when the command fails ( exits with non-zero value) you need a `||`... |
13046192 | How to change the default shell in Linux? | 413 | 2012-10-24 09:15:37 | <p>How is it possible to change the default shell? The <code>env</code> command currently says:</p>
<pre><code>SHELL=/bin/tcsh
</code></pre>
<p>and I want to change that to Bash.</p>
| 808,901 | 859,227 | 2024-05-05 14:13:11 | 13,046,283 | 572 | 2012-10-24 09:21:12 | 258,355 | 2018-03-09 18:42:17 | https://stackoverflow.com/q/13046192 | https://stackoverflow.com/a/13046283 | <p>Try linux command <code>chsh</code>.</p>
<p>The detailed command is <code>chsh -s /bin/bash</code>.
It will prompt you to enter your password.
Your default login shell is <code>/bin/bash</code> now. <strong>You must log out and log back in to see this change.</strong></p>
<p>The following is quoted from man page:<... | <p>Try linux command <code>chsh</code>.</p> <p>The detailed command is <code>chsh -s /bin/bash</code>. It will prompt you to enter your password. Your default login shell is <code>/bin/bash</code> now. <strong>You must log out and log back in to see this change.</strong></p> <p>The following is quoted from man page:<... | 58, 387, 390, 421, 8599 | bash, environment, linux, shell, tcsh | <h1>How to change the default shell in Linux?</h1>
<p>How is it possible to change the default shell? The <code>env</code> command currently says:</p>
<pre><code>SHELL=/bin/tcsh
</code></pre>
<p>and I want to change that to Bash.</p>
| q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 314 | bash | # How to change the default shell in Linux?
How is it possible to change the default shell? The `env` command currently says:
```
SHELL=/bin/tcsh
```
and I want to change that to Bash. | Try linux command `chsh`.
The detailed command is `chsh -s /bin/bash`.
It will prompt you to enter your password.
Your default login shell is `/bin/bash` now. **You must log out and log back in to see this change.**
The following is quoted from man page:
> The chsh command changes the user login shell. This determin... |
6381229 | How to kill all processes matching a name? | 347 | 2011-06-17 04:07:56 | <p>Say I want to kill every process containing the word amarok. I can print out the commands I want to execute. But how do I actually make the shell execute them. ie.</p>
<pre><code>ps aux | grep -ie amarok | awk '{print "kill -9 " $2}'
Output:
kill -9 3052
kill -9 3071
kill -9 3076
kill -9 3077
kill -9 3079
kill -9 3... | 356,420 | 357,198 | 2025-07-25 15:20:26 | 6,381,266 | 571 | 2011-06-17 04:16:19 | 263,969 | 2011-06-17 04:16:19 | https://stackoverflow.com/q/6381229 | https://stackoverflow.com/a/6381266 | <p>From <code>man 1 pkill</code></p>
<pre><code>-f The pattern is normally only matched against the process name.
When -f is set, the full command line is used.
</code></pre>
<p>Which means, for example, if we see these lines in <code>ps aux</code>:</p>
<pre><code>apache 24268 0.0 2.6 388152 27116 ? ... | <p>From <code>man 1 pkill</code></p> <pre><code>-f The pattern is normally only matched against the process name. When -f is set, the full command line is used. </code></pre> <p>Which means, for example, if we see these lines in <code>ps aux</code>:</p> <pre><code>apache 24268 0.0 2.6 388152 27116 ? ... | 390, 1231, 5779 | command-line, kill, shell | <h1>How to kill all processes matching a name?</h1>
<p>Say I want to kill every process containing the word amarok. I can print out the commands I want to execute. But how do I actually make the shell execute them. ie.</p>
<pre><code>ps aux | grep -ie amarok | awk '{print "kill -9 " $2}'
Output:
kill -9 3052
kill -9 3... | q.PostTypeId = 1; a.PostTypeId = 2; EXISTS tag '%bash%' OR '%shell%'; a.Body contains code block; q.Score > 5; a.Score > 10 | 315 | bash | # How to kill all processes matching a name?
Say I want to kill every process containing the word amarok. I can print out the commands I want to execute. But how do I actually make the shell execute them. ie.
```
ps aux | grep -ie amarok | awk '{print "kill -9 " $2}'
Output:
kill -9 3052
kill -9 3071
kill -9 3076
kil... | From `man 1 pkill`
```
-f The pattern is normally only matched against the process name.
When -f is set, the full command line is used.
```
Which means, for example, if we see these lines in `ps aux`:
```
apache 24268 0.0 2.6 388152 27116 ? S Jun13 0:10 /usr/sbin/httpd
apache 24272 0.0 ... |
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