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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
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.




All commands from sorted by
Terminal - All commands - 11,488 results
netstat -alnp | grep ::80
find . -type d -execdir du -sh '{}' ';' | grep -E "[0-9]+K" | sed 's/^[0-9\.]\+K[\t ]\+//' | tr "\n" "\0" | xargs -0 rm -rf
last reboot
ps -eo stat,pid,user,command | egrep "^STAT|^D|^R"
2009-02-20 19:00:17
User: jyoder
Functions: egrep ps

Want to know why your load average is so high? Run this command to see what processes are on the run queue. Runnable processes have a status of "R", and commands waiting on I/O have a status of "D".

On some older versions of Linux may require -emo instead of -eo.

On Solaris: ps -aefL -o s -o user -o comm | egrep "^O|^R|COMMAND"

2009-02-20 18:07:03
User: jcgam69

Only a few characters of the previous command are necessary.

tcpdump -nn -v -i eth0 -s 1500 -c 1 'ether[20:2] == 0x2000'
2009-02-20 18:02:27
User: spif
Functions: tcpdump

This gives you lots of nifty Cisco network information like VLAN tag, port and switch information.

2009-02-20 17:38:49
User: betsubetsu

If you typed 'sl', put the cursor on the 'l' and hit ctrl-t to get 'ls'.

yes 'Y'|gdb -ex 'p close(1)' -ex 'p creat("/tmp/output.txt",0600)' -ex 'q' -p pid
2009-02-20 17:36:57
User: adminzim
Functions: yes

This command uses the debugger to attach to a running process, and reassign a filehandle to a file.

The two commands executed in gdb are

p close(1) which closes STDOUT


p creat("/tmp/filename",0600)

which creates a file and opens it for output. Since file handles are assigned

sequentially, this command opens the file in place of STDOUT and once the process continues, new output to STDOUT will instead be written to our capture file.

who am i
2009-02-20 16:26:11
User: ozymandias
Functions: who

In my work environment, we log onto the servers as our user ('user', in the sample ouput), and 'sudo su - root' to other accounts. This trick allows us to return the account name we logged in as -- and not the account name we currently are ('root', in this example).

Using this trick, you can build other commands:

Set your CVSROOT env variable to your account name:

CVSROOT=$(who am i | awk '{print $1}')@cvs.server.example.com:/cvsroot

SCP a file to another server:

scp file.txt $(who am i | awk '{print $1}')@some.other.server.com:.

This works out great in my environment, as we can include this in our documentation and make the comands more easy to copy/paste for different users, and not have to set all sorts of variables, or modify the docs for each user.

whoami gives you the name of the user you currently are, not the user you logged on originally as.

who gives you a listing of every single person logged onto the server.

who am i gives you the name of the user you logged on as, and not who you changed to with su.

Look at the following scenario:



su -

# whoami


# who am i

user pts/51 2009-02-13 10:24 (:0.0)

whoami != who am i

curl -u USERNAME:PASSWORD -d "" http://twitter.com/friendships/create/NAMEOFNEWFRIEND.xml?follow=true
2009-02-20 14:30:57
User: reklis

replace username, password, and nameofnewfriend with proper values. Remember to escape things like ! or & in your password

echo "hello world" | festival --tts
2009-02-20 14:00:50
Functions: echo

The Festival Speech Synthesis System converts text into sound.

Or: links -dump http://youfavoritewebsite.com | festival --tts

ctrl + r
2009-02-20 13:28:19
User: sixtus

This is not actually a command, it's just a keyboard shortchut. But a very useful one.

find / -name *~ -delete
pushd +2; pushd -2
2009-02-20 12:26:18
User: betsubetsu

'pushd +1' is equivalent to 'pushd'. Can be 'pushd +3' or more generaly 'pushd +N'. Can also be 'pushd -N'.

More description in 'man bash'.

FLOOR=0; RANGE=10; number=0; while [ "$number" -le $FLOOR ]; do number=$RANDOM; let "number %= $RANGE"; done; echo $number
2009-02-20 09:33:56
User: raphink
Functions: echo
Tags: bash

This one-liner outputs a random number between the values given for FLOOR and RANGE.

xset b off
2009-02-20 07:40:14
User: dizzgo

Disable the annoying beep in xterm

<alt> + <print screen/sys rq> + <R> - <S> - <E> - <I> - <U> - <B>
2009-02-20 07:28:56
User: dizzgo

If the machine is hanging and the only help would be the power button, this key-combination will help to reboot your machine (more or less) gracefully.

R - gives back control of the keyboard

S - issues a sync

E - sends all processes but init the term singal

I - sends all processes but init the kill signal

U - mounts all filesystem ro to prevent a fsck at reboot

B - reboots the system

Save your file before trying this out, this will reboot your machine without warning!


du -b --max-depth 1 | sort -nr | perl -pe 's{([0-9]+)}{sprintf "%.1f%s", $1>=2**30? ($1/2**30, "G"): $1>=2**20? ($1/2**20, "M"): $1>=2**10? ($1/2**10, "K"): ($1, "")}e'
/lib/ld-linux.so.2 =(echo -e '#include <stdio.h>\nint main(){printf("c one liners\\n");}' | gcc -x c -o /dev/stdout -)
2009-02-20 06:06:29
User: mrtheplague
Functions: c++ echo gcc

is the runtime linker/loader for ELF binaries on Linux.

=(cmd) is a zsh trick to take the output for the command "inside" it and save it to a temporary file.

echo -e 'blah' | gcc -x c -o /dev/stdout -

pipes the C source to gcc. -x c tells gcc that it's compiling C (which is required if it's reading from a pipe). -o /dev/stdout - tells it to write the binary to standard output and read the source from standard input.

because of the the =() thing, the compiled output is stashed in a tempfile, which the loader then runs and executes, and the shell tosses the tempfile away immediately after running it.

mkfifo /tmp/fifo; cat /tmp/fifo | nc -l -p 1234 | tee -a to.log | nc machine port | tee -a from.log > /tmp/fifo
2009-02-20 04:00:15
User: prutser
Functions: cat mkfifo tee

Forwards localhost:1234 to machine:port, running all data through your chain of piped commands. The above command logs inbound and outbound traffic to two files.

Tip: replace tee with sed to manipulate the data in real time (use "sed -e 's/400 Bad Request/200 OK/'" to tweak a web server's responses ;-) Limitless possibilities.

this command is to see oracle instance process on linux server
php -i|grep -i max
2009-02-20 03:29:11
User: rjamestaylor

Show the maximum settings in effect for PHP at the command line.

echo 1 > /proc/sys/kernel/sysrq; echo b > /proc/sysrq-trigger
2009-02-20 00:37:18
User: tsaavik
Functions: echo

This will cause your machine to INSTANTLY reboot. No un-mounting of drives or anything.

Very handy when something has gone horribly wrong with your server in that co-location facility miles away with no remote hands!

Suspect this works with all 2.2, 2.4 and 2.6 Linux kernels compiled with magic-syskey-request support.

if [[ `:$(cal);echo $_` == `date +%d` ]]; then ROTATE_MONTHLY_TABLES_SCRIPT;fi
2009-02-20 00:28:05
User: tsaavik

This is handy to just shove into a daily cron entry. If you do use cron, make sure to escape the %d with \%d or it will fail.