Hide

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

OpenID
or
Sign in Register

First-time OpenID users will be automatically assigned a username which can be changed after signing in.

Hide

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:

Hide

News

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.
Hide

Tags

Hide

Functions

Hide

Credits

Site by David Winterbottom (user root).

All commands from sorted by
Terminal - All commands - 11,586 results
netstat -alnp | grep ::80
2009-02-20 19:45:53
User: jdunn
Functions: grep netstat
2
Up
Down
Show what PID is listening on port 80 on Linux
Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
find . -type d -execdir du -sh '{}' ';' | grep -E "[0-9]+K" | sed 's/^[0-9\.]\+K[\t ]\+//' | tr "\n" "\0" | xargs -0 rm -rf
2009-02-20 19:44:49
User: jdunn
Functions: du find grep rm sed tr xargs
0
Up
Down
Remove all directories less than 1 MB in size in or below current directory
Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
last reboot
2009-02-20 19:21:40
User: jyoder
Functions: last
3
Up
Down
Find out the last times your system was rebooted (for the duration of wtmp).
Show sample output | Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
ps -eo stat,pid,user,command | egrep "^STAT|^D|^R"
2009-02-20 19:00:17
User: jyoder
Functions: egrep ps
4
Up
Down
Find the processes that are on the runqueue. Processes with a status of

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"

Show sample output | Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
!previous_command
2009-02-20 18:07:03
User: jcgam69
-4
Up
Down
run a previous command

Only a few characters of the previous command are necessary.

Comments (5) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
tcpdump -nn -v -i eth0 -s 1500 -c 1 'ether[20:2] == 0x2000'
2009-02-20 18:02:27
User: spif
Functions: tcpdump
15
Up
Down
Get Cisco network information

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

Show sample output | Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
ctrl-t
2009-02-20 17:38:49
User: betsubetsu
21
Up
Down
Switch 2 characters on a command line.

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

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
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
7
Up
Down
Redirect a filehandle from a currently running process.

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

and

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.

Show sample output | Comments (4) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
who am i
2009-02-20 16:26:11
User: ozymandias
Functions: who
-18
Up
Down
find out who you logged onto the machine as -- and not just who you are now

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:

whoami

user

su -

# whoami

root

# who am i

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

whoami != who am i

Show sample output | Comments (9) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
curl -u USERNAME:PASSWORD -d "" http://twitter.com/friendships/create/NAMEOFNEWFRIEND.xml?follow=true
2009-02-20 14:30:57
User: reklis
1
Up
Down
Follow a new friend on twitter

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

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
echo "hello world" | festival --tts
2009-02-20 14:00:50
User: jacquesloonen
Functions: echo
7
Up
Down
Synthesize text as speech

The Festival Speech Synthesis System converts text into sound.

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

Show sample output | Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
ctrl + r
2009-02-20 13:28:19
User: sixtus
6
Up
Down
Search previous commands from your .bash_history

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

Show sample output | Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
find / -name *~ -delete
2009-02-20 13:15:23
User: lfamorim
Functions: find
3
Up
Down
Remove Backup Files

Remove all text backup files.

Show sample output | Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
pushd +2; pushd -2
2009-02-20 12:26:18
User: betsubetsu
1
Up
Down
pushd rotates the stack so that the second directory comes at the top.

'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'.

Show sample output | Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
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
-1
Up
Down
Random integer number between FLOOR and RANGE

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

Show sample output | Comments (3) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
xset b off
2009-02-20 07:40:14
User: dizzgo
7
Up
Down
Mute xterm

Disable the annoying beep in xterm

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
<alt> + <print screen/sys rq> + <R> - <S> - <E> - <I> - <U> - <B>
2009-02-20 07:28:56
User: dizzgo
99
Up
Down
Reboot machine when everything is hanging

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!

http://en.wikipedia.org/wiki/Magic_SysRq_key

Comments (10) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
w3m
2009-02-20 07:22:07
User: ustctapper
-25
Up
Down
test
Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
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'
2009-02-20 06:11:31
User: mrtheplague
Functions: du perl sort
35
Up
Down
Sort the size usage of a directory tree by gigabytes, kilobytes, megabytes, then bytes.

Probably only works with GNU du and modern perls.

Show sample output | Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
/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
6
Up
Down
C one-liners
/lib/ld-linux.so.2

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.

Show sample output | Comments (3) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
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
26
Up
Down
Intercept, monitor and manipulate a TCP connection.

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.

Comments (3) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
this command is to see oracle instance process on linux server
2009-02-20 03:40:29
User: kirakast
Functions: command
-22
Up
Down
ps- ef | grep pmon
Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
php -i|grep -i max
2009-02-20 03:29:11
User: rjamestaylor
-2
Up
Down
Show "Max" settings for PHP

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

Show sample output | Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
echo 1 > /proc/sys/kernel/sysrq; echo b > /proc/sysrq-trigger
2009-02-20 00:37:18
User: tsaavik
Functions: echo
7
Up
Down
Force machine to reboot no matter what (even if /sbin/shutdown is hanging)

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.

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
if [[ `:$(cal);echo $_` == `date +%d` ]]; then ROTATE_MONTHLY_TABLES_SCRIPT;fi
2009-02-20 00:28:05
User: tsaavik
1
Up
Down
Run a command if today is the last day of the month

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.

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate