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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

Top Tags



Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

Commands using echo from sorted by
Terminal - Commands using echo - 1,317 results
HDD=$(df | awk ' NR>3 (S=$5) (M=$6) { if (S>90) print "Your Systems "M" is """S" Full" } ') ; [[ $HDD ]] && echo "$HDD" | mail -s "Hard-Drives Full" [email protected] -- -f [email protected] >/dev/null
seq 10 |xargs -n1 echo Printing line
2009-10-15 11:05:35
User: Waldirio
Functions: echo seq xargs
Tags: echo xargs seq

Nice command to create a list, you can create too with for command, but this is so faster.

n=$RANDOM$RANDOM$RANDOM; let "n %= 10000000000"; echo $n
ping -q -c1 -w3 brandx.jp.sme 2&>1 /dev/null || echo brandx.jp.sme ping failed | mail -ne -s'Server unavailable' [email protected]
2009-10-13 14:13:04
User: mccalni
Functions: echo mail ping
Tags: bash ping mail

Joker wants an email if the Brand X server is down. Set a cron job for every 5 mins with this line and he gets an email when/if a ping takes longer than 3 seconds.

echo $RANDOM$RANDOM$RANDOM |cut -c3-12
dpkg --get-selections | cut -f1 | while read pkg; do dpkg -L $pkg | xargs -I'{}' bash -c 'if [ ! -d "{}" ]; then echo "{}"; fi' | tr '\n' '\000' | du -c --files0-from - | tail -1 | sed "s/total/$pkg/"; done
2009-10-12 14:57:54
User: pykler
Functions: bash cut du echo read sed tail tr xargs
Tags: Debian wajig

Calculates the size on disk for each package installed on the filesystem (or removed but not purged). This is missing the

| sort -rn

which would put the biggest packges on top. That was purposely left out as the command is slightly on the slow side

Also you may need to run this as root as some files can only be checked by du if you can read them ;)

b="http://2010.utosc.com"; for p in $( curl -s $b/presentation/schedule/ | grep /presentation/[0-9]*/ | cut -d"\"" -f2 ); do f=$(curl -s $b$p | grep "/static/slides/" | cut -d"\"" -f4); if [ -n "$f" ]; then echo $b$f; curl -O $b$f; fi done
2009-10-11 17:28:46
User: danlangford
Functions: cut echo grep
Tags: curl cut for UTOSC

miss a class at UTOSC2010? need a refresher? use this to curl down all the presentations from the UTOSC website. (http://2010.utosc.com) NOTE/WARNING this will dump them in the current directory and there are around 37 and some are big - tested on OSX10.6.1

ifs () { echo -n "${IFS}"|hexdump -e '"" 10/1 "'\''%_c'\''\t" "\n"' -e '"" 10/1 "0x%02x\t" "\n\n"'|sed "s/''\|\t0x[^0-9]//g; $,/^$/d"
2009-10-10 22:41:35
User: dennisw
Functions: echo hexdump sed

You can display, save and restore the value of $IFS using conventional Bash commands, but these functions, which you can add to your ~/.bashrc file make it really easy.

To display $IFS use the function ifs shown above. In the sample output, you can see that it displays the characters and their hexadecimal equivalent.

This function saves it in a variable called $saveIFS:

sifs () { saveIFS=$IFS; }

Use this function to restore it

rifs () { IFS=$saveIFS; }

Add this line in your ~/.bashrc file to save a readonly copy of $IFS:

declare -r roIFS=$IFS

Use this function to restore that one to $IFS

rrifs () { IFS=$roIFS; }
head -c10 <(echo $RANDOM$RANDOM$RANDOM)
2009-10-09 15:09:02
User: jgc
Functions: echo head
Tags: HEAD random

Makes use of $RANDOM environment variable.

if [ "$testnum" -eq "$testnum" 2>/dev/null ]; then echo It is numeric; fi
2009-10-09 14:57:27
User: jgc
Functions: echo

Using the standard numeric comparison but suppressing the STDERR output acts as the simplest way to check a value is numeric. See sample output for some examples.

echo $X | egrep "^[0-9]+$"
for USER in `ls /var/spool/cron`; do echo "=== crontab for $USER ==="; echo $USER; done
tput smcup; echo "Doing some things..."; sleep 2; tput rmcup
2009-10-08 16:48:04
User: jgc
Functions: echo sleep tput

Very useful for interactive scripts where you would like to return the terminal contents to its original state before the script was run. This would be similar to how vi exits and returns you to your original terminal screen.

Save and clear the terminal contents with:

tput smcup

Execute some commands, then restore the saved terminal contents with:

tput rmcup
for USER in `cut -d ":" -f1 </etc/passwd`; do crontab -u ${USER} -l 1>/dev/null 2>&1; if [ ! ${?} -ne 0 ]; then echo -en "--- crontab for ${USER} ---\n$(crontab -u ${USER} -l)\n"; fi; done
2009-10-07 20:51:01
User: tharant
Functions: crontab echo

This is how I list the crontab for all the users on a given system that actually have a crontab.

You could wrap it with a function block and place it in your .profile or .bashrc for quick access.

There's prolly a simpler way to do this. Discuss.

echo "vertical text" | fold -1
sitepass() { echo -n "$@" | md5sum | sha1sum | sha224sum | sha256sum | sha384sum | sha512sum | gzip - | strings -n 1 | tr -d "[:space:]" | tr -s '[:print:]' | tr '!-~' 'P-~!-O' | rev | cut -b 2-11; history -d $(($HISTCMD-1)); }
2009-10-01 20:14:57
User: syssyphus
Tags: Security

usage: sitepass MaStErPaSsWoRd example.com

description: An admittedly excessive amount of hashing, but this will give you a pretty secure password, It also eliminates repeated characters and deletes itself from your command history.

tr '!-~' 'P-~!-O' # this bit is rot47, kinda like rot13 but more nerdy

rev # this avoids the first few bytes of gzip payload, and the magic bytes.

echo $(</tmp/foo)
expdp user/password FLASHBACK_SCN=$(echo -e "select current_scn from v\$database;" | sqlplus / as sysdba 2>/dev/null| grep [0-9][0-9][0-9][0-9][0-9][0-9]*)
2009-10-01 08:55:20
User: peshay
Functions: as echo grep

Creates a consistent datapumpt export on an Oracle database with the current sequence number, while the system is running and changes happens on the database.

check_dns_no() { for i in $* ; do if `wget -O - -q http://www.norid.no/domenenavnbaser/whois/?query=$i.no | grep "no match" &>/dev/null` ; then echo $i.no "available" ; fi ; sleep 1 ;done }
2009-09-30 21:17:33
User: xeor
Functions: echo grep sleep
Tags: wget dig dns

Mostly for Norwegians, but easily adoptable to others. Very handy if you are brainstorming for a new domainname.

Will only display the available ones..

You can usually do this better with dig, but if you dont have dig, or the TLD only have an online service to check with, this will be usefull..

(crontab -l; echo '* * * * * dmesg -c'; ) | crontab -
2009-09-30 18:13:38
User: syssyphus
Functions: crontab dmesg echo

this is helpful because dmesg is where i/o errors, etc are logged to... you will also be able to see when the system reboots or someone attaches a thumb drive, etc.

don't forget to set yourself up in /etc/aliases to get roots email.

echo "Starting Daemon"; ( while :; do sleep 15; echo "I am still running =]"; done ) & disown -h -ar $!
s=124890; array=($(echo $s | sed 's/./& /g')); echo ${array[@]}; echo ${!array[@]}
2009-09-29 12:30:04
User: tatsu
Functions: echo sed

Convert string to array using echo and sed =)

[ `date --date='next day' +'%B'` == `date +'%B'` ] || echo 'end of month'
PERMA () { echo "$@" >> ~/.bashrc; }
2009-09-28 16:03:24
User: zlemini
Functions: echo

Simple function to permanently add an alias to your profile.

Tested on bash and Ksh, bash version above.

Here is the ksh version: PERMA () { print "$@" >> ~/.profile; }

Sample usage:

PERMA alias la='ls -a'

echo -e "\e[32m"; while :; do for i in {1..16}; do r="$(($RANDOM % 2))"; if [[ $(($RANDOM % 5)) == 1 ]]; then if [[ $(($RANDOM % 4)) == 1 ]]; then v+="\e[1m $r "; else v+="\e[2m $r "; fi; else v+=" "; fi; done; echo -e "$v"; v=""; done
2009-09-27 15:30:38
User: dennisw
Functions: echo
Tags: color

I like the fact the Patola's version uses only ones and zeros, but I also like the sparse output of the other versions. This one combines both of those features and eliminates some unnecessary cruft.

You can vary the sparseness by changing "$(($RANDOM % 5))" to another number. The number in this term "$(($RANDOM % 4))" controls how frequently the numbers are output bold.