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2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
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2010-09-24 - OAuth and pagination problems fixed
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Commands using echo from sorted by
Terminal - Commands using echo - 1,227 results
sudo port selfupdate ; echo '---------' ; sudo port upgrade outdated
count=0;while IFS= read -r -d '' line; do echo "${line#* }"; ((++count==5)) && break; done < <(find . -type f -printf '%s %p\0' | sort -znr)
2013-03-19 17:19:26
User: sharfah
Functions: echo find read sort
Tags: sort find head,

This command is more robust because it handles spaces, newlines and control characters in filenames. It uses printf, not ls, to determine file size.

A=$(ip addr show dev eth0); A=${A##*inet }; echo ${A%%/*}
2013-03-13 23:07:37
User: charley
Functions: echo

bash only - no grep, sed, awk, whatever - zero overhead

alternatively using ifconfig instead of "ip addr ..."

A=$(ifconfig eth0); A=${A##*inet addr:}; echo ${A%% *}

which <command> > /dev/null 2>&1 && echo Success!
2013-03-13 10:04:42
User: skkzsh
Functions: echo which
Tags: which


which <command> > /dev/null 2>&1 || echo Error!

For example, I write

which colordiff > /dev/null 2>&1 && alias diff=colordiff

in my `~/.bashrc`.

echo "ls" > script.bash; gpg -c script.bash; cat script.bash.gpg | gpg -d --no-mdc-warning | bash
2013-03-10 09:34:12
User: betsubetsu
Functions: cat echo gpg

echo "ls" > script.bash;

This is my script, a simple 'ls'.

gpg -c script.bash;

Here I encrypt and passord-protect my script. This creates file script.bash.gpg.

cat script.bash.gpg | gpg -d --no-mdc-warning | bash

Here I open file script.bash.gpg, decrypt it and execute it.

read -p 'Script: ' S && C=$S.crypt H='eval "$((dd if=$0 bs=1 skip=//|gpg -d)2>/dev/null)"; exit;' && gpg -c<$S|cat >$C <(echo $H|sed s://:$(echo "$H"|wc -c):) - <(chmod +x $C)
2013-03-10 08:59:45
User: rodolfoap
Functions: cat chmod echo gpg read sed wc

(Please see sample output for usage)

Use any script name (the read command gets it) and it will be encrypted with the extension .crypt, i.e.:

myscript --> myscript.crypt

You can execute myscript.crypt only if you know the password. If you die, your script dies with you.

If you modify the startup line, be careful with the offset calculation of the crypted block (the XX string).

Not difficult to make script editable (an offset-dd piped to a gpg -d piped to a vim - piped to a gpg -c directed to script.new ), but not enough space to do it on a one liner.

Sorry for the chmod on parentheses, I dont like "-" at the end.

Thanks flatcap for the subshell abbreviation to /dev/null

echo 'magic(3)' | matlab -nodisplay
2013-03-09 14:08:09
User: skkzsh
Functions: echo

Execute matlab sentences in shell script:

for var in `seq 0 0.2 1` ; do

echo "my_function($var);" | matlab -nodisplay


echo "eval \"\$(dd if=\$0 bs=1 skip=XX 2>/dev/null|gpg -d 2>/dev/null)\"; exit" > script.secure; sed -i s:XX:$(stat -c%s script.secure): script.secure; gpg -c < script.bash >> script.secure; chmod +x script.secure
2013-03-09 11:16:48
User: rodolfoap
Functions: chmod echo gpg sed stat

(Please see sample output for usage)

script.bash is your script, which will be crypted to script.secure

script.bash --> script.secure

You can execute script.secure only if you know the password. If you die, your script dies with you.

If you modify the startup line, be careful with the offset calculation of the crypted block (the XX string).

Not difficult to make script editable (an offset-dd piped to a gpg -d piped to a vim - piped to a gpg -c directed to script.new ), but not enough space to do it on a one liner.

echo "template file: ";read tpl;echo "new file(s separated w. space):"; read fl;touch $fl;find $fl -exec cp -ap $tpl "{}" \;
2013-03-08 10:00:36
User: knoppix5
Functions: cp echo find read touch

make a bunch of files with the same permissions, owner, group, and content as a template file

(handy if you have much to do w. .php, .html files or alike)

find . -type f -exec echo echo rm {} '|' batch ';'|bash
2013-03-01 15:14:08
User: Ztyx
Functions: batch echo find rm

While `echo rm * | batch` might seem to work, it might still raise the load of the system since `rm` will be _started_ when the load is low, but run for a long time. My proposed command executes a new `rm` execution once every minute when the load is small.

Obviously, load could also be lower using `ionice`, but I still think this is a useful example for sequential batch jobs.

find ~/ -type d \( -wholename '/dev/*' -o -wholename '/sys/*' -o -wholename '/proc/*' \) -prune -o -exec test -w {} \; -exec echo {} writable \; 2>/dev/null
2013-02-27 13:18:47
User: cas_alexi
Functions: echo find test

su www-apache/ftp user and then

check readable: find ~/ -type d \( -wholename '/dev/*' -o -wholename '/sys/*' -o -wholename '/proc/*' \) -prune -o -exec test -r {} \; -exec echo {} readable \; 2>/dev/null

check writable: find ~/ -type d \( -wholename '/dev/*' -o -wholename '/sys/*' -o -wholename '/proc/*' \) -prune -o -exec test -w {} \; -exec echo {} writable \; 2>/dev/null

grep " lm " /proc/cpuinfo > /dev/null && echo "64-bit" || echo "32-bit"
echo "main(i){for(i=0;;i++)putchar(((i*(i>>8|i>>9)&46&i>>8))^(i&i>>13|i>>6));}" | gcc -x c - && ./a.out | aplay
2013-02-17 21:31:04
User: SNDR
Functions: echo gcc
Tags: aplay

Try modifying the numbers in the "(i*(i>>8|i>>9)&46&i>>8))^(i&i>>13|i>>6)" part.

Crudely stolen from http://www.xkcdb.com/9067

alias private_mode='unset HISTFILE && echo -e "\033[1m[\033[0m\033[4m*\033[0m\033[1m] \033[0m\033[4mprivate mode activated.\033[0m"'
2013-02-17 00:03:37
User: s__
Functions: alias echo

same as "unset HISTFILE" - but the advantage is that you can "tab-complete" it and when you do, you won't mistype it (which could lead to not unsetting the HISTFILE).

put the alias in the ~/.bash_profile or ~/.bashrc file in your users home directory, respawn, enjoy! :)

if [[ "$1" =~ ^[0-9]+$ ]]; then echo "Is a number"; fi
cat /proc/cpuinfo | grep " lm " > /dev/null && echo 64 bits || echo 32 bits
2013-02-11 22:54:26
User: agd
Functions: cat echo grep

CPU flags:

rm --> 16-bit processor (real mode)

tm --> 32-bit processor (? mode)

lm --> 64-bit processor (long mode)

if [[ lm = $(cat /proc/cpuinfo | grep " lm ") ]] ; then echo "64 bits" ; else echo "32 bits" ; fi
2013-02-11 22:40:46
User: agd
Functions: cat echo grep

CPU flags:

rm --> 16-bit processor (real mode)

tm --> 32-bit processor (? mode)

lm --> 64-bit processor (long mode)

grep -q '\<lm\>' /proc/cpuinfo && echo 64 bits || echo 32 bits
2013-02-09 13:01:36
User: sputnick
Functions: echo grep

This command tell you if your hardware is 32 or 64 bits even if you install a 32bits OS on a 64 bits hardware.

If your distro don't support the -q switch, try doing :

grep &>/dev/null '\<lm\>' /proc/cpuinfo && echo 64 bits || echo 32 bits
(echo -e "HTTP/1.1 200 Ok\n\r"; tail -f /var/log/syslog) | nc -l 1234
2013-02-09 06:15:42
User: adimania
Functions: echo tail

This one is tried and tested for Ubuntu 12.04. Works great for tailing any file over http.

load=`uptime|awk -F',' '{print $3}'|awk '{print $3}'`; if [[ $(echo "if ($load > 1.0) 1 else 0" | bc) -eq 1 ]]; then notify-send "Load $load";fi
2013-02-06 08:30:24
User: adimania
Functions: awk echo

I run this via crontab every one minute on my machine occasionally to see if a process is eating up my system's resources.

FOR %%c in (C:\Windows\*.*) DO (echo file %%c)
2013-01-31 15:19:54
User: jmcclosk
Functions: echo file

You can implement a FOR loop to act on one or more files returned from the IN clause. We originally found this in order to GPG decrypt a file using wildcards (where you don't know exactly the entire file name, i.e.: Test_File_??????.txt, where ?????? = the current time in HHMMSS format). Since we won't know the time the file was generated, we need to use wildcards. And as a result of GPG not handling wildcards, this is the perfect solution. Thought I would share this revelation. :-)

echo 'foo' | tee >(wc -c) >(grep o) >(grep f)
2013-01-31 09:54:18
User: totti
Functions: echo grep tee wc
Tags: tee output input

Output of a command as input to many

dd if=/dev/zero of=T bs=1024 count=10240;mkfs.ext3 -q T;E=$(echo 'read O;mount -o loop,offset=$O F /mnt;'|base64|tr -d '\n');echo "E=\$(echo $E|base64 -d);eval \$E;exit;">F;cat <(dd if=/dev/zero bs=$(echo 9191-$(stat -c%s F)|bc) count=1) <(cat T;rm T)>>F
2013-01-31 01:38:30
User: rodolfoap

This is just a proof of concept: A FILE WHICH CAN AUTOMOUNT ITSELF through a SIMPLY ENCODED script. It takes advantage of the OFFSET option of mount, and uses it as a password (see that 9191? just change it to something similar, around 9k). It works fine, mounts, gets modified, updated, and can be moved by just copying it.


The file is composed of three parts:

a) The legible script (about 242 bytes)

b) A random text fill to reach the OFFSET size (equals PASSWORD minus 242)

c) The actual filesystem

Logically, (a)+(b) = PASSWORD, that means OFFSET, and mount uses that option.

PLEASE NOTE: THIS IS NOT AN ENCRYPTED FILESYSTEM. To improve it, it can be mounted with a better encryption script and used with encfs or cryptfs. The idea was just to test the concept... with one line :)

It applies the original idea of http://www.commandlinefu.com/commands/view/7382/command-for-john-cons for encrypting the file.

The embedded bash script can be grown, of course, and the offset recalculation goes fine. I have my own version with bash --init-file to startup a bashrc with a well-defined environment, aliases, variables.

echo 'echo "cd `pwd`" >> $VIRTUAL_ENV/bin/postactivate' >> $VIRTUAL_ENV/../postmkvirtualenv
echo '#!/bin/bash' > junk.sh ; find . -iname *.pdf -type f -printf \p\s\2\a\s\c\i\i\ \"%p\"\ \ \"%p\.\t\x\u\"\;\ \p\a\r\ \<\"%p\.\t\x\u\"\ \>\"%p\.\t\x\t\"\ \;\ \r\m\ \"%p\.\t\x\u\"\ \\n >>junk.sh; chmod 766 junk.sh; ./junk.sh ; rm junk.sh
2013-01-27 21:29:08
User: p0g0
Functions: chmod echo find rm

Linux users wanting to extract text from PDF files in the current directory and its sub-directories can use this command. It requires "bash", "ps2ascii" and "par", and the PARINIT environment variable sanely set (see man par). WARNING: the file "junk.sh" will be created, run, and destroyed in the current directory, so you _must_ have sufficient rights. Edit the command if you need to avoid using the file name "junk.sh"