nl
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bash
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returns the first 100 bytes in the file
head -c 100 file
Return the list of files named "filename" that are 50 megabytes or larger
find / -size +50M -iname "filename"
Returns the single most recent file in a directory
ls -t | head -n1
Reverse the order of lines in "myfile.txt" using BSD "tail" command
tail -r myfile.txt
Reversibly sorts content of the '${TMP}/${SCRIPT_NAME}.kb' file, comparing human readable numbers in file strings.
cat ${TMP}/${SCRIPT_NAME}.kb|sort -rh;
Reversibly sorts content of the '${TMP}/${SCRIPT_NAME}.name' file
cat ${TMP}/${SCRIPT_NAME}.name|sort -r;
Reversibly sorts content of the '${TMP}/${SCRIPT_NAME}.pid' file, comparing human readable numbers in file strings.
cat ${TMP}/${SCRIPT_NAME}.pid|sort -rh;
Reverse the space separated words in "35 53 102 342"
echo 35 53 102 342|tr ' ' '\n'|tac|tr '\n' ' '
Reverse the text in $input by taking each 4 characters as each units and save the result in variable 'output'
output=$(echo $input | fold -w4 | tac | tr -d \\n)
Revert $string value and print first 20 space-separated fields
echo $string | rev | cut -d ' ' -f -20
Run "./configure" with a new environment variable CC set to the full path of the command 'cc'
CC=$(which cc) ./configure
Run "./configure" with a new environment variable CC set to the full path of the command 'gcc'
CC=$(which gcc) ./configure
Run "command" on server "host" as user "user"
echo "command" | ssh user@host
Run 'chmod 0644' on all files in the current directory tree
find . -type f -exec chmod 0644 {} \;
Run 'chmod 0755' on all directories in the current directory tree
find . -type d -exec chmod 0755 {} \;
Runs `file' on every file in or below the current directory.
find . -type f -exec file '{}' \;
Run 'make -e' with an environment variable 'HOSTNAME' set to the system hostname
HOSTNAME=$(hostname) make -e
Run 'somecommand' in an environment without the FOO variable.
env -u FOO somecommand
Run 'top' in batch mode (don't accept user input) with delay of 1 second between updates, and duplicate the standard output to file 'output.log' in current directory.
top -b -d 1 | grep myprocess.exe | tee output.log
Run .makeall.sh in an empty environment.
env -i ./makeall.sh
Run commands "df -k;uname -a" on server "192.168.79.134"
echo "df -k;uname -a" | ssh 192.168.79.134
Run command 'su whoami' on host 'remotehost'
echo "su whoami" |ssh remotehost
Run command specified by $line, replace space (' ') with newline and save the output to variable 'arr'
arr=$( $line | tr " " "\n")
Run the file command on every regular file under current directory
find . -type f -exec file '{}' \;
Run the find command with all shell positional arguments
`which find` "$@" -print0;
run ksh shell as user apache
su apache -s /bin/ksh
run ls command on *.pl files
find . -name "*.pl" -exec ls -ld {} \;
run ls command on files found
find . -name "*.pl" -exec ls -ld {} \;
Run perl -V (displays informations about perl's setup) in an empty environment.
env -i perl -V
Run rsync with options specified by variable OPTS, copying directory(ies) specified by variable FIND, and to destination specified by variable BACKUPDIR.
rsync $OPTS $FIND $BACKUPDIR
same as above example with -exec , in this example with -OK it should ask for confirmation before executing the rm command . that is called user intractive command
find . -name core -ok rm {} \;
Save "something" into variable "param" in ksh
echo something | read param
Save $line line in history
history -s "$line"
Save 'echo whatever you "want your" command to be' in history
history -s 'echo whatever you "want your" command to be'
Save 'foo' into variable 'bar' in ksh
echo foo | read bar
Save a comma separated list of all $MY_DIRECTORY/*/ directories to variable 'FOLDER'
FOLDERS=`ls -dm $MY_DIRECTORY/*/ | tr -d ' '`
Save a comma separated list of all directories under current directory tree to variable 'FOLDER'
FOLDERS=$(find . -type d -print0 | tr '\0' ',')
Save a line of 100 random characters either "." or " " in variable "foo"
foo=$(cat /dev/urandom | tr -dc '. ' | fold -w 100 | head -1)
Save a list of all 755 permission files/directories under $dir directory tree to the variable 'files'
files="$(find $dir -perm 755)"
Save a list of all the files/directories under current directory tree to a file named 'foo'
find . -fprint foo
Save a unique list of the currently logged in usernames to variable "line"
line=$(who | cut -d' ' -f1 | sort -u)
Save absolute path of "$path" that must exist along with all parents to variable "abspath"
abspath=$(readlink -e $path)
Save absolute path of "$path" that may not exist to variable "abspath"
abspath=$(readlink -m $path)
Save the absolute path of "$path" to variable "full_path"
full_path=`readlink -fn -- $path`
Save the absolute path of "$path" to variable "fullpath"
fullpath=`readlink -f "$path"`
Save absolute path of "/home/nohsib/dvc/../bop" in variable "absolute_path"
absolute_path=$(readlink -m /home/nohsib/dvc/../bop)
Save the absolute path of the current script to variable "SELF"
SELF=$(readlink /proc/$$/fd/255)
Save the absolute path of the current script to variable "SELF"
SELF=`readlink /proc/$$/fd/255`
Save the absolute path of the current script to variable "SELF"
actual_path=$(readlink -f "${BASH_SOURCE[0]}")
Save the absolute path of the current script to variable "SELF"
script="`readlink -f "${BASH_SOURCE[0]}"`"
Save actual working directory in variable "target_PWD"
target_PWD=$(readlink -f .)
Save all directories under the current directory as a comma separated list in variable "FOLDERS"
FOLDERS=$(find $PWD -type d | paste -d, -s)
Save all directories under the current directory as a comma separated list in variable "FOLDERS"
FOLDERS=$(find . -type d | paste -d, -s)
Save all entries that are wrapped around with opening and closing square brackets in file 'FILENAME' to variable 'var'
var=`egrep -o '\[.*\]' FILENAME | tr -d ][`
Saves bytes count of the value of '$each' variable.
a=$(echo $each | wc -c)
Saves byte size of $myvar variable value in the 'var2' variable.
var2=$(echo $myvar | wc -c)
Save the canonical filename of "$BASH_SOURCE" in variable "me"
me=$(readlink --canonicalize --no-newline $BASH_SOURCE)
Save the canonical path of "$dir/$file" in variable "path"
path=`readlink --canonicalize "$dir/$file"`
Save count of lines from file $file matching with pattern $filter and not matching with pattern $nfilter in variable 'totalLineCnt'
totalLineCnt=$(cat "$file" | grep "$filter" | grep -v "$nfilter" | wc -l | grep -o '^[0-9]\+');
Save the current date to 'DATE' variable
DATE=$(echo `date`)
Save the current time formatted according to the format string "%Y-%m-%d %H:%M:%S" to the variable 'CDATE'
CDATE=$(date "+%Y-%m-%d %H:%M:%S")
Save the current user name in variable "myvariable"
myvariable=$(whoami)
Save the current working directory and the directory name of the current script to variable "DIR"
DIR=`pwd`/`dirname $0`
Save the current working directory to variable "CURRENT"
CURRENT=`pwd`
Save the current working directory with resolved symbolic links to variable "real1"
real1=$(pwd -P)
Save the date 222 days before today to the variable 'date_222days_before_TodayDay'
date_222days_before_TodayDay=$(date --date="222 days ago" +"%d")
Save the day of the year from the time string "20131220" to variable 'DATECOMING'
DATECOMING=$(echo `date -d "20131220" +%j`)
Save the directory name of the canonical path to the current script in variable "MY_DIR"
MY_DIR=$(dirname $(readlink -f $0))
Save the directory of the full path to the current script in variable "dir"
dir=$(dirname $(readlink -m $BASH_SOURCE))
Save the directory of the full path to the current script in variable "dir"
dir=$(dirname $(readlink /proc/$$/fd/255))
Saves file sctipt.sh size in 'size' variable.
size=`cat script.sh | wc -c`
Save the first "." separated field of the system host name to variable "HOSTZ"
HOSTZ=$( hostname | cut -d. -f1 )
Save the first two letters of the system host name to variable "DC"
DC=`hostname | cut -b1,2`
Save the first three octets of the host name's IP address to variable "subnet"
subnet=$(hostname -i | cut -d. -f1,2,3)
Save first IP address of domain 'google.com' in 'address' variable
address=$(dig +short google.com | grep -E '^[0-9.]+$' | head -n 1)
Save the first line of "$j" into variable "k" in ksh
echo $j | read k
Save first one of space separated parts of each line in $LOCKFILE file to the 'CURRENT_PID_FROM_LOCKFILE' variable
CURRENT_PID_FROM_LOCKFILE=`cat $LOCKFILE | cut -f 1 -d " "`
Save the first word of the first difference in ".dir_list_2" compared to ".dir_list_1" into variable "extract_dir"
extract_dir=$(diff .dir_list_1 .dir_list_2 | grep '>' | head -1 | cut -d' ' -f2)
Saves folder path where target of symbolic link $file file is located in 'base' variable.
base=$(dirname $(readlink $file))
Save the FQDN host name of the system in variable "fhost"
fhost=`hostname -f`
Save the FQDN host name of the system in variable "hnd"
hnd=$(hostname -f)
Save full path of command "mktemp" to variable "MKTEMP"
MKTEMP=`which mktemp`
Save the full path of command "oracle" to variable "path"
path=`which oracle`
Save full path of command "rm" to variable "RM"
RM=`which rm`
Save full path of command "tr" to variable "TR"
TR=`which tr`
Save the full path of command "~/f" to variable "foo"
foo=`which ~/f`
Save host name in variable "thisHOSTNAME"
thisHOSTNAME=`hostname`
Save in QUEUE_PIDS variable only pid numbers that stored in $NEW_PIDS variable
QUEUE_PIDS=$(comm -23 <(echo "$NEW_PIDS" | sort -u) <(echo "$LIMITED_PIDS" | sort -u) | grep -v '^$')
Saves index number of file 'script.sh' in the 'inode' variable.
inode=`ls -i ./script.sh | cut -d" " -f1`
Saves invoked command 'check_script_call=$(history |tail -1|grep myscript.sh )' in variable 'check_script_call', preceeding by its number in history.
check_script_call=$(history |tail -1|grep myscript.sh )
Save the latest modification time (in format "%T@ %t" of any file under "./$dir" to variable "timestamp"
timestamp=$(find ./$dir -type f -printf "%T@ %t\\n" | sort -nr -k 1,2 | head -n 1)
Saves listing of a current folder in 'OUTPUT' variable.
OUTPUT="$(ls -1)"
Save the list of all .py files under and below the current directory that contain "something" in their pathnames to output.txt
find . -name '*.py' | tee output.txt | xargs grep 'something'
Save list of groups which user $line belongs to and not matching pattern "_unknown|sciences|everyone|netaccounts" in 'results' variable
results=$(groups "$line" | tr ' ' '\n' | egrep -v "_unknown|sciences|everyone|netaccounts")
Saves list of logged in users in system together with 'USER' header in the 'a' variable.
a=`w|cut -d' ' -f1`;
Saves location of file $1 in 'dir' variable.
dir=$(dirname -- "$1")
Saves location of file $1 in 'dir_context' variable.
dir_context=$(dirname -- "$1")
Save the logical current working directory to variable "basedir"
basedir=$(pwd -L)
Save long listing of all files listed in file 'filenames.txt' to 'listing' variable
listing=$(ls -l $(cat filenames.txt))
Save long listing of all running processes in the 'log' file, and save number of process strings that contain 'cntps' in the 'cnt' variable.
cnt=`ps -ef| tee log | grep "cntps"|grep -v "grep" | wc -l`