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.

Get involved!

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

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

Universal configuration monitoring and system of record for IT.

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:



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 read from sorted by
Terminal - Commands using read - 303 results
shmore(){ local l L M="`echo;tput setab 4&&tput setaf 7` --- SHMore --- `tput sgr0`";L=2;while read l;do echo "${l}";((L++));[[ "$L" == "${LINES:-80}" ]]&&{ L=2;read -p"$M" -u1;echo;};done;}
2010-04-21 00:40:37
User: AskApache
Functions: echo read
cat mod_log_config.c | shmore


shmore < mod_log_config.c

Most pagers like less, more, most, and others require additional processes to be loaded, additional cpu time used, and if that wasn't bad enough, most of them modify the output in ways that can be undesirable.

What I wanted was a "more" pager that was basically the same as running:

cat file

Without modifying the output and without additional processes being created, cpu used, etc. Normally if you want to scroll the output of cat file without modifying the output I would have to scroll back my terminal or screen buffer because less modifies the output.

After looking over many examples ranging from builtin cat functions created for csh, zsh, ksh, sh, and bash from the 80's, 90s, and more recent examples shipped with bash 4, and after much trial and error, I finally came up with something that satisifed my objective. It automatically adjusts to the size of your terminal window by using the LINES variable (or 80 lines if that is empty) so

This is a great function that will work as long as your shell works, so it will work just find if you are booted in single user mode and your /usr/bin directory is missing (where less and other pagers can be). Using builtins like this is fantastic and is comparable to how busybox works, as long as your shell works this will work.

One caveat/note: I always have access to a color terminal, and I always setup both the termcap and the terminfo packages for color terminals (and/or ncurses and slang), so for that reason I stuck the

tput setab 4; tput setaf 7

command at the beginning of the function, so it only runs 1 time, and that causes the -- SHMore -- prompt to have a blue background and bright white text.

This is one of hundreds of functions I have in my http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html">.bash_profile at http://www.askapache.com/">AskApache.com, but actually won't be included till the next update.

If you can improve this in any way at all please let me know, I would be very grateful! ( Like one thing I want is to be able to continue to the next screen by pressing any key instead of now having to press enter to continue)

/bin/grep - ipranges.txt | while read line; do ipcalc $line ; done | grep -v deag
2010-04-20 21:13:00
User: tf8
Functions: grep read

Taking file with ip ranges, each on it's own line like:

cat ipranges.txt

command returns deaggregated ip ranges using ipcalc deaggregate feature like that:

Useful for configuring nginx geo module

ls | grep *.txt | while read file; do cat $file >> ./output.txt; done;
read -sn1 -p "Press any key to continue..."; echo
2010-04-13 20:37:26
User: vibaf
Functions: read

Just added -sn1

-s = silent

-n1 = only one symbol needed to continue after the insert

read -p "Press enter to continue.."
2010-04-13 13:05:09
User: brubaker
Functions: read

Waiting for a key stroke. You can use this with a ";" behind to build a command chain.

du -cks * | sort -rn | while read size fname; do for unit in k M G T P E Z Y; do if [ $size -lt 1024 ]; then echo -e "${size}${unit}\t${fname}"; break; fi; size=$((size/1024)); done; done
wget randomfunfacts.com -O - 2>/dev/null | grep \<strong\> | sed "s;^.*<i>\(.*\)</i>.*$;\1;" | while read FUNFACT; do notify-send -t $((1000+300*`echo -n $FUNFACT | wc -w`)) -i gtk-dialog-info "RandomFunFact" "$FUNFACT"; done
2010-04-02 09:43:32
User: mtron
Functions: grep read sed wc wget

extension to tali713's random fact generator. It takes the output & sends it to notify-osd. Display time is proportional to the lengh of the fact.

while $8;do read n;[ $n = "$l" ]&&c=$(($c+1))||c=0;echo $c;l=$n;done
2010-03-31 00:41:08
User: florian
Functions: read
Tags: bash read Game

hold period (or whatever character) and hit enter after a second. You need to make the next line of periods the same length as the previous line... score starts at 0 and increase each time length of line is same.

count="1" ; while true ; do read next ; if [[ "$next" = "$last" ]] ; then count=$(($count+1)) ; echo "$count" ; else count="1" ; echo $count ; fi ; last="$next" ; done
2010-03-30 04:02:29
User: dabom
Functions: echo read true
Tags: bash read Game

Really bored during class so I made this...

Basically, you hold period (or whatever) and hit enter after a second and you need to make the next line of periods the same length as the previous line...

My record was 5 lines of the same length.

It's best if you do it one handed with your pointer on period and ring on enter.

ls | while read filename; do tar -czvf "$filename".tar.gz "$filename"; rm "$filename"; done
2010-03-29 08:10:38
User: Thingymebob
Functions: ls read rm tar

Compresses each file individually, creating a $fileneame.tar.gz and removes the uncompressed version, usefull if you have lots of files and don't want 1 huge archive containing them all. you could replace ls with ls *.pdf to just perform the action on pdfs for example.

rpm --querytags | egrep -v HEADERIMMUTABLE | sort | while read tag ; do rpm -q --queryformat "$tag: [%{$tag} ]\n" -p $SomeRPMfile ; done
2010-03-25 05:40:48
Functions: egrep read rpm sort

If you want to relocate a package on your own, or you just want to know what those PREIN/UN and POSTIN/UN scripts will do, this will dump out all that detail simply.

You may want to expand the egrep out other verbose flags like CHANGELOGTEXT etc, as your needs require.

It isn't clear, but the formatting around $tag is important: %{$tag} just prints out the first line, while [%{$tag }] iterates thru multi-line output, joining the lines with a space (yes, there's a space between the g and } characters. To break it out for all newlines, use [%{$tag\n}] but the output will be long.

This is aside from rpm2cpio | cpio -ivd to extract the package files.

( last ; ls -t /var/log/wtmp-2* | while read line ; do ( rm /tmp/wtmp-junk ; zcat $line 2>/dev/null || bzcat $line ) > /tmp/junk-wtmp ; last -f /tmp/junk-wtmp ; done ) | less
2010-03-16 04:17:16
Functions: last ls read rm zcat

When your wtmp files are being logrotated, here's an easy way to unpack them all on the fly to see more than a week in the past. The rm is the primitive way to prevent symlink prediction attack.

find . -iname '*.mp3' | while read song; do mpg321 ${song} -w - | oggenc -q 9 -o ${song%.mp3}.ogg -; done
2010-03-14 11:34:35
User: renich
Functions: find mpg321 read
Tags: ogg mpg321

This is not recommended... lossy -> lossy = lossier.

Still, you can do it! ;)

while read f;do echo "$f";done < <(find .)
2010-03-02 14:22:22
Functions: echo find read

Read all contents from current directory and display to stdout.

find . |while read f;do echo "$f";done
2010-03-02 14:21:15
Functions: echo find read

Read all contents from current directory and display it on stdout.

ls *.wav | while read f; do lame "$f" -o "$(echo $f | cut -d'.' -f1)".mp3; done;
uri_escape(){ echo -E "$@" | sed 's/\\/\\\\/g;s/./&\n/g' | while read -r i; do echo $i | grep -q '[a-zA-Z0-9/.:?&=]' && echo -n "$i" || printf %%%x \'"$i" done }
2010-02-13 01:39:51
User: infinull
Functions: echo grep printf read sed

This one uses hex conversion to do the converting and is in shell/sed only (should probably still use the python/perl version).

find /dev/vg00 -type b |while read L; do lvextend -m 1 $L /dev/disk/<disk> ; done
set-proxy () { P=webproxy:1234; DU="fred"; read -p "username[$DU]:" USER; printf "%b"; UN=${USER:-$DU}; read -s -p "password:" PASS; printf "%b" "\n"; export http_proxy="http://${UN}:${PASS}@$P/"; export ftp_proxy="http://${UN}:${PASS}@$P/"; }
2010-02-04 13:12:59
User: shadycraig
Functions: export printf read set

Prompts the user for username and password, that are then exported to http_proxy for use by wget, yum etc

Default user, webproxy and port are used.

Using this script prevent the cleartext user and pass being in your bash_history and on-screen

while read l; do echo $RANDOM "$l"; done | sort -n | cut -d " " -f 2-
2010-02-03 22:36:34
User: ketil
Functions: cut echo read sort

If you need to randomize the lines in a file, but have an old sort commands that doesn't support the -R option, this could be helpful. It's easy enough to remember so that you can create it as a script and use that.

It ain't real fast. It ain't safe. It ain't super random. Do not use it on untrusted data. It requires bash for the $RANDOM variable to work.

find . -maxdepth 1 -type f| xargs sha1sum | sed 's/^\(\w*\)\s*\(.*\)/\2 \1/' | while read LINE; do mv $LINE; done
(IFS=; sed 's/^[]0;[^^G]*^G/^M/g' <SessionLog> | while read -n 1 ITEM; do [ "$ITEM" = "^M" ] && ITEM=$'\n'; echo -ne "$ITEM"; sleep 0.05; done; echo)
2010-01-20 16:11:32
User: jgc
Functions: echo read sed sleep
Tags: read script

This command will play back each keystroke in a session log recorded using the script command. You'll need to replace the ^[ ^G and ^M characters with CTRL-[, CTRL-G and CTRL-M. To do this you need to press CTRL-V CTRL-[ or CTRL-V CTRL-G or CTRL-V CTRL-M.

You can adjust the playback typing speed by modifying the sleep.

If you're not bothered about seeing each keypress then you could just use:

cat session.log
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; }
removedir () { echo "Deleting the current directory $PWD Are you sure?"; read human; if [[ "$human" = "yes" ]]; then blah=$(echo "$PWD" | sed 's/ /\\ /g'); foo=$(basename "$blah"); rm -Rf ../$foo/ && cd ..; else echo "I'm watching you" | pv -qL 10; fi; }
2010-01-17 11:34:38
User: oshazard
Functions: basename cd echo read rm sed


Version 1.1

removedir () { echo "You are about to delete the current directory $PWD Are you sure?"; read human; if [[ "$human" = "yes" ]]; then blah=$(echo "$PWD" | sed 's/ /\\ /g'); foo=$(basename "$blah"); rm -Rf ../$foo/ && cd ..; else echo "I'm watching you" | pv -qL 10; fi; }


Folders with spaces

Version 1.0

removedir () { echo "You are about to delete the current directory $PWD Are you sure?"; read human; if [[ "$human" = "yes" ]]; then blah=`basename $PWD`; rm -Rf ../$blah/ && cd ..; else echo "I'm watching you" | pv -qL 10; fi; }


Hidden directories (.dotdirectory)

Version 0.9

rmdir () { echo "You are about to delete the current directory $PWD. Are you sure?"; read human; if [[ "$human" = "yes" ]]; then blah=`basename $PWD`; rm -Rf ../$blah/ && cd ..; else echo "I'm watching you" | pv -qL 10; fi; }

Removes current directory with recursive and force flags plus basic human check. When prompted type yes

1. [[email protected] ~]$ ls

foo bar

2. [[email protected] ~]$ cd foo

3. [[email protected] foo]$ removedir

4. yes

5. rm -Rf foo/

6. [[email protected] ~]$

7. [[email protected] ~]$ ls


ps -ef | grep user | awk '{print $2}' | while read pid; do echo $pid ; pfiles $pid| grep portnum; done
2010-01-11 12:34:51
User: sharfah
Functions: awk echo grep ps read

My old Solaris server does not have lsof, so I have to use pfiles.