Commands tagged bash sorted by votes

Commands tagged bash (821)

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determine if a shared library is compiled as 32bit or 64bit

file displays a files type the -L flag means follow sym-links (as libraries are often sym-linked to another this behavior is likely preferred) more complex behavior (*two* grep commands!) could be used to determine if the file is or is not a shared library.
This is sample output - yours may be different.
-3

file -L <library> | grep -q '64-bit' && echo 'library is 64 bit' || echo 'library is 32 bit'

infinull · 2010-03-07 06:31:35 3
sorts /dev/random
This is sample output - yours may be different.
-3

find /dev/ -name random -exec bash -c '[ -r $0 -a -w $0 ] && dd if=$0 | sort | dd of=$0' {} \;

winky · 2010-03-19 12:17:21 5
Bash function to see if the day ends in "y"

For those days when you need to know if something is happening because the day ends in "y". Show Sample Output
This is sample output - yours may be different.
```
$ ends_in_y
1
```
-3

function ends_in_y() { if [ `date +%A | sed -e 's/$^.*$$.$$/\2/'` == "y" ]; then echo 1; else echo 0; fi }

allrightname · 2010-04-06 20:14:34 7
Remove executable bit from all files in the current directory recursively, excluding other directories, firm permissions
This is sample output - yours may be different.
-3

find . -type f -exec chmod a-x {} \;

bandie91 · 2010-07-19 09:02:59 4

make ping run a little faster

Show Sample Output

-3

alias ping='ping -n'

wincus · 2011-01-19 23:39:21 3

Selecting a random file/folder of a folder

The same thing using only Bash built-in's. For readability I've kept the variables out, but it could me made extremely more compact (and totally unreadable!) by stuffing everything inside the single echo command.
This is sample output - yours may be different.
-3

IFS=$'\n'; LIST=`ls -1`; let TOT=`echo $LIST | wc -w`-1 ; array=($LIST); echo "Selected ${array[ ($RANDOM % $TOT) ]}"

ntropia · 2011-03-13 21:30:44 3
BASH: Print shell variable into AWK
This is sample output - yours may be different.
-3

MyVAR=84; awk '{ print "'"$MyVAR"'" }'

EBAH · 2011-04-14 15:49:50 3
Overcome Bash's expansion order

no need for seq or eval
This is sample output - yours may be different.
-3

mkdir ${1..10}

linuts · 2011-07-23 19:20:35 6
Renaming files removing some unwanted extension

For those files in current folder that would be shown in `ls *ext`, for some extension ext, move/rename that file removing the .ext suffix from the file name. It uses Bash's parameter substitution, as seen in http://tldp.org/LDP/abs/html/parameter-substitution.html#PCTPATREF (for analog use in prefix, see http://tldp.org/LDP/abs/html/parameter-substitution.html#PSOREX2 )
This is sample output - yours may be different.
-3

for i in *ext; do mv $i ${i%.ext}; done

paulochf · 2011-11-13 03:58:08 8
convert from decimal to hexadecimal
This is sample output - yours may be different.
-3

hex() { echo $1 16op | dc; }

mwgamera · 2011-12-12 17:12:31 3
Move files older than 30 days in current folder to "old" folder

Will move in that case every file in the current folder older than 30 days to the "old" folder Replace "mv $i old/" by any command such as rm / echo to do something different.
This is sample output - yours may be different.
-3

for i in $(find . -mtime +30); do mv $i old/; done

valferon · 2014-02-05 01:24:45 7
Reports size of all folders in the current folder. Useful when burning CD's and DVD's
This is sample output - yours may be different.
-4

export IFS=$'\n';for dir in $( ls -l | grep ^d | cut -c 52-);do du -sh $dir; done

whatshisname · 2009-02-28 20:30:15 5
!$ - The last argument to the previous command

After a command is run in bash, !$ is set to the last (space-delimited) argument of the command. Great for running several commands against the same file in a row.
This is sample output - yours may be different.
-4

svn status app/models/foo.rb; svn commit -m "Changed file" !$

ggoodale · 2009-03-22 23:14:06 5
Press Any Key to Continue

how to finish command or script without any output Show Sample Output
This is sample output - yours may be different.
```
root@ubuserver:~# read enterKey

root@ubuserver:~#
```
-4

read enterKey

bbmarek · 2009-12-29 00:18:32 7
download file1 file2 file3 file4 .... file 100

With counter format [001, 002, ..., 999] , nice with pictures or wallpapers collections.
This is sample output - yours may be different.
-4

for file in $(seq -f '%03.f' 1 $TOTAL ); do echo "($file/$TOTAL)"; curl -f -O http://domain.com/Name_$file.ext; done

nordri · 2010-01-12 15:23:44 6
Combining text files into one file

the last person who posted used the most roundabout way to concatinate files, there's a reason there's a "conCATinate" command... Using this method, you also get to choose the order of the files, below another person just did *.txt > combined.txt which is fine but the order depends on the implementation of "cat" which is probably alphabetical order of filenames. Show Sample Output
This is sample output - yours may be different.
```
$cat stdHeader tableOfContents introduction body conclusion worksCited index  > researchPaper
$pwd; ls;
/home/ginoman/researchPapers/sample/
body                conclusion                index
introduction        researchPaper             stdHeader
tableOfContents     worksCited
$
```
-4

cat file1 ... fileN > combinedFile;

GinoMan2440 · 2010-04-17 01:00:04 4
Download a file securely via a remote SSH server
This is sample output - yours may be different.
-4

scp $user@$server:$path/to/file .

burned · 2010-08-02 16:26:10 4
before writing a new script

Writes out the shebang line (#!/bin/bash) to the script.
This is sample output - yours may be different.
-4

echo '#!'$(which bash) > script.sh

sharfah · 2012-02-06 08:25:27 8
Create a directory and change into it at the same time
This is sample output - yours may be different.
-4

function mkdcd () { mkdir "$1" && cd "$1" }

shinokada · 2013-08-31 12:48:13 26
..(), go up in directory tree, func to long please refer to description

many have aliases like: alias ...="cd ../../" alias ....="cd ../../../" and so furth. ..() mitigates to need for those aliases, see sample output for an example # .. -> go up 1 directory # .. 4 -> go up 4 directories ..() { local DIR='' declare -i NUM=0 if [[ ${1} =~ ^[1-9][0-9]*$ ]] then while (( ${NUM} < ${1:-1} )) do DIR="${DIR}../" NUM=$(( ${NUM} + 1 )) done else DIR=.. fi cd "${DIR}" } Show Sample Output
This is sample output - yours may be different.
```
[ ~/temp/foo/bar/baz ] $ .. 3
[ ~/temp ] $ 
```
-4

[ ~/temp/foo/bar/baz ] $ .. 3

Xk2c · 2015-01-01 20:41:17 10
Kill a background job

Show Sample Output
This is sample output - yours may be different.
```
$ ping www.google.com &
$ jobs
[1]+  Running                 ping www.google.com &
$ kill %1
[1]+  Terminated              ping www.google.com &
$
```
-5

kill %1

prayer · 2009-04-09 11:54:13 4

Remove current directory (REVISED)

Credit goes to "eightmillion" Show Sample Output

-5

removedir(){ read -p "Delete the current directory $PWD ? " human;if [ "$human" = "yes" ]; then [ -z "${PWD##*/}" ] && { echo "$PWD not set" >&2;return 1;}; rm -Rf ../"${PWD##*/}"/ && cd ..; else echo "I'm watching you" | pv -qL 10; fi; }

oshazard · 2010-01-20 08:01:21 9

View the newest xkcd comic.

Add an alias to your .bashrc that allows you to issue the command xkcd to view (with gwenview) the newest xkcd comic... I know there are thousands of them out there but this one is at least replete with installer and also uses a more concise syntax... plus, gwenview shows you the downloading progress as it downloads the comic and gives you a more full featured viewing experience.
This is sample output - yours may be different.
-5

echo alias xkcd="gwenview `w3m -dump http://xkcd.com/|grep png | awk '{print $5}'` 2> /dev/null" >> .bashrc

GinoMan2440 · 2010-01-30 20:38:16 5
Short one line while loop that outputs parameterized content from one file to another
This is sample output - yours may be different.
-5

while read col1 col23; do echo $col1; done < three-column.txt > first-column.txt

infinull · 2010-07-09 03:59:20 3
View the newest xkcd comic.

KISS To get a random xkcd comic: xdg-open http://dynamic.xkcd.com/random/comic/
This is sample output - yours may be different.
-5

xdg-open http://xkcd.com/

unixmonkey8024 · 2010-08-25 19:14:11 3
‹ First < 30 31 32 33 >

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Fast file backup

This is a BASH feature. The above command will create a backup of "filename" called "filename.DATE", where DATE is the actual day in %Y%m%d (year, month and day numbers together) format.

history manipulation

make make install !-2 && !-1

Find last reboot time

Displays time of last system boot

Convert seconds to [DD:][HH:]MM:SS

Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Route outbound SMTP connections through a addtional IP address rather than your primary

Find if the command has an alias

Single use vnc-over-ssh connection

This command 1. SSH into a machine 2. Tunnels VNC port to your local computer ("-L 5900:localhost:5900") 3. Runs a single use vnc server ("x11vnc -safer -localhost -nopw -once -display :0") 4. Goes into the background ("-f") 5. Runs VNC viewer on the local computer connecting to the remote machine via the newly created SSH tunnel ("vinagre localhost:5900")

Remove duplicate rows of an un-sorted file based on a single column

The command (above) will remove any duplicate rows based on the FIRST column of data in an un-sorted file. The '$1' represents a positional parameter. You can change both instances of '$1' in the command to remove duplicates based on a different column, for instance, the third: $ awk '{ if ($3 in stored_lines) x=1; else print; stored_lines[$3]=1 }' infile.txt > outfile.txt Or you can change it to '$0' to base the removal on the whole row: $ awk '{ if ($0 in stored_lines) x=1; else print; stored_lines[$0]=1 }' infile.txt > outfile.txt ** Note: I wouldn't use this on a MASSIVE file, unless you're RAM-rich ;) **

Create a mirror of a local folder, on a remote server

Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

Displays the attempted user name, ip address, and time of SSH failed logins on Debian machines

A variation of a script I found on this site and then slimmed down to just use awk. It displays all users who have attempted to login to the box and failed using SSH. Pipe it to the sort command to see which usernames have the most failed logins.

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Commands tagged bash (821)

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