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.

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.
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

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!
Hide

Top Tags

Hide

Functions

Hide

Credits

Commands tagged function from sorted by
Terminal - Commands tagged function - 113 results
buf() { f=${1%%.*};e=${1/$f/};cp -v $1 $f-$(date +"%Y%m%d_%H%M%S")$e;}
2010-12-15 09:50:04
User: unefunge
Functions: cp date
0

"infix" version in bash (4.x+)

Remove -v to make it silent.

BTW: The OP forgot to use "cat" and "nmap" ;-) I had a good laugh though.

buf () {oldname=$1; if [ "$oldname" != "" ]; then datepart=$(date +%Y-%m-%d); firstpart=`echo $oldname | cut -d "." -f 1`; newname=`echo $oldname | sed s/$firstpart/$firstpart.$datepart/`; cp -i ${oldname} ${newname}; fi }
2010-12-14 19:58:34
User: Seebi
Functions: cp cut date sed
-3

This backup function preserve the file suffix allowing zsh suffix aliases and desktop default actions to work with the backup file too.

buf () { cp $1{,$(date +%Y%m%d_%H%M%S)}; }
2010-12-14 14:02:03
User: unefunge
Functions: cp date
2

1. you don't need to prepend the year with 20 - just use Y instead of y

2. you may want to make your function a bit more secure:

buf () { cp ${1?filename not specified}{,$(date +%Y%m%d_%H%M%S)}; }

typeset -f <function name>; declare -f <function name>
2010-11-24 15:59:42
User: unefunge
3

no need to reinvent the wheel.

Thanks to the OP for the "obsolete" hint. 'declare' may come in pretty handy on systems paranoid about "up-to-dateness"

bm () { ... see description }
bm() { export BM${1?"bookmark name missing"}="$PWD" ; }; forget() { unset BM${1?"bookmark name missing"} ; }
2010-11-19 12:15:11
User: unefunge
Functions: export unset
2

pushd and popd are your friends, but sometimes they're just incompatible with the way one works...

Two shell functions:

bm bookmarkname - "bookmarks" the current directory, just 'cd $BMbookmarkname' to return to it.

forget bookmarkname - unsets the 'bookmarkname' variable. It isn't mandatory, they cease to exist when the session ends.

wget -O xkcd_$(date +%y-%m-%d).png `lynx --dump http://xkcd.com/|grep png`; eog xkcd_$(date +%y-%m-%d).png
for _a in {A..Z} {a..z};do _z=\${!${_a}*};for _i in `eval echo "${_z}"`;do echo -e "$_i: ${!_i}";done;done|cat -Tsv
2

This uses some tricks I found while reading the bash man page to enumerate and display all the current environment variables, including those not listed by the 'env' command which according to the bash docs are more for internal use by BASH. The main trick is the way bash will list all environment variable names when performing expansion on ${!A*}. Then the eval builtin makes it work in a loop.

I created a function for this and use it instead of env. (by aliasing env).

This is the function that given any parameters lists the variables that start with it. So 'aae B' would list all env variables starting wit B. And 'aae {A..Z} {a..z}' would list all variables starting with any letter of the alphabet. And 'aae TERM' would list all variables starting with TERM.

aae(){ local __a __i __z;for __a in "$@";do __z=\${!${__a}*};for __i in `eval echo "${__z}"`;do echo -e "$__i: ${!__i}";done;done; }

And my printenv replacement is:

alias env='aae {A..Z} {a..z} "_"|sort|cat -v 2>&1 | sed "s/\\^\\[/\\\\033/g"'

From: http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

atb() { l=$(tar tf $1); if [ $(echo "$l" | wc -l) -eq $(echo "$l" | grep $(echo "$l" | head -n1) | wc -l) ]; then tar xf $1; else mkdir ${1%.tar.gz} && tar xf $1 -C ${1%.tar.gz}; fi ;}
2010-10-16 05:50:32
User: elfreak
Functions: echo grep head mkdir tar wc
10

This Anti-TarBomb function makes it easy to unpack a .tar.gz without worrying about the possibility that it will "explode" in your current directory. I've usually always created a temporary folder in which I extracted the tarball first, but I got tired of having to reorganize the files afterwards. Just add this function to your .zshrc / .bashrc and use it like this;

atb arch1.tar.gz

and it will create a folder for the extracted files, if they aren't already in a single folder.

This only works for .tar.gz, but it's very easy to edit the function to suit your needs, if you want to extract .tgz, .tar.bz2 or just .tar.

More info about tarbombs at http://www.linfo.org/tarbomb.html

Tested in zsh and bash.

UPDATE: This function works for .tar.gz, .tar.bz2, .tgz, .tbz and .tar in zsh (not working in bash):

atb() { l=$(tar tf $1); if [ $(echo "$l" | wc -l) -eq $(echo "$l" | grep $(echo "$l" | head -n1) | wc -l) ]; then tar xf $1; else mkdir ${1%.t(ar.gz||ar.bz2||gz||bz||ar)} && tar xf $1 -C ${1%.t(ar.gz||ar.bz2||gz||bz||ar)}; fi ;}

UPDATE2: From the comments; bepaald came with a variant that works for .tar.gz, .tar.bz2, .tgz, .tbz and .tar in bash:

atb() {shopt -s extglob ; l=$(tar tf $1); if [ $(echo "$l" | wc -l) -eq $(echo "$l" | grep $(echo "$l" | head -n1) | wc -l) ]; then tar xf $1; else mkdir ${1%.t@(ar.gz|ar.bz2|gz|bz|ar)} && tar xf $1 -C ${1%.t@(ar.gz|ar.bz2|gz|bz|ar)}; fi ; shopt -u extglob}
for p in `ps L|cut -d' ' -f1`;do echo -e "`tput clear;read -p$p -n1 p`";ps wwo pid:6,user:8,comm:10,$p kpid -A;done
2

While going through the source code for the well known ps command, I read about some interesting things.. Namely, that there are a bunch of different fields that ps can try and enumerate for you. These are fields I was not able to find in the man pages, documentation, only in the source.

Here is a longer function that goes through each of the formats recognized by the ps on your machine, executes it, and then prompts you whether you would like to add it or not. Adding it simply adds it to an array that is then printed when you ctrl-c or at the end of the function run. This lets you save your favorite ones and then see the command to put in your .bash_profile like mine at : http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

Note that I had to do the exec method below in order to pause with read.

t ()

{

local r l a P f=/tmp/ps c='command ps wwo pid:6,user:8,vsize:8,comm:20' IFS=' ';

trap 'exec 66

exec 66 $f && command ps L | tr -s ' ' >&$f;

while read -u66 l >&/dev/null; do

a=${l/% */};

$c,$a k -${a//%/} -A;

yn "Add $a" && P[$SECONDS]=$a;

done

}

awk "BEGIN{ print $* }"
2010-10-07 16:13:41
User: maelcum
Functions: awk
4

works with fractions like 1/3.5

calc() { bc <<< $*; }
calc() { python -c "from math import *; print $1"; }
2010-10-07 08:26:39
User: asmaier
Functions: python
1

This function defines a command line calculator that handles everything pythons math module can handle, e.g. trigonometric functions, sqrt, log, erf, ... (see http://docs.python.org/library/math.html). It even knows about the constants pi and e.

shout() { curl -s "http://shoutkey.com/new?url=${1}" | sed -n "/<h1>/s/.*href=\"\([^\"]*\)\".*/\1/p" ;}
shout () { curl -s "http://shoutkey.com/new?url=$1" | sed -n 's/\<h1\>/\&/p' | sed 's/<[^>]*>//g;/</N;//b' ;}
2010-10-04 23:50:54
User: elfreak
Functions: sed
4

Just add this function to your .zshrc / .bashrc, and by typing "shout *URL*" you get a randomly chosen English word that ShoutKey.com uses to short your URL. You may now go to shoutkey.com/*output_word* and get redirected. The URL will be valid for 5 minutes.

(I've never used sed before, so I'll be quite glad if someone could straighten up the sed commands and combine them (perhaps also removing the whitespace). If so, I'll update it right away ;) )

yt () mplayer -fs -quiet $(youtube-dl -g "$1")
2010-09-29 18:48:19
User: elfreak
15

A function for streaming youtube to mplayer.

The option "-g" for youtube-dl tells it to output the direct video URL, instead of downloading the video.

"-fs" tells MPlayer to go FullScreen, and "-quit" makes it less verbose.

Requires: youdube-dl ( http://bitbucket.org/rg3/youtube-dl/ )

(Tested in zsh)

eog `curl -s http://xkcd.com/ | sed -n 's/<h3>Image URL.*: \(.*\)<\/h3>/\1/p'`
xdg-open http://xkcd.com/
2010-08-25 19:14:11
-5

KISS

To get a random xkcd comic:

xdg-open http://dynamic.xkcd.com/random/comic/
xkcd() { wget -qO- http://xkcd.com/ | sed -n 's#^<img src="\(http://imgs.[^"]\+\)"\s\+title="\(.\+\?\)"\salt.\+$#eog "\1"\necho '"'\2'#p" | bash ; }
2010-08-25 15:44:31
User: John_W
Functions: bash sed wget
0

This function displays the latest comic from xkcd.com. One of the best things about xkcd is the title text when you hover over the comic, so this function also displays that after you close the comic.

To get a random xkcd comic use the following:

xkcdrandom() { wget -qO- http://dynamic.xkcd.com/comic/random | sed -n 's#^<img src="\(http://imgs.[^"]\+\)"\s\+title="\(.\+\?\)"\salt.\+$#eog "\1"\necho '"'\2'#p" | bash; }

These are just a bit shorter than the ones eigthmillion wrote, however his version didn't work as expected on my laptop for some reason (I got the title-tag first), so these build a command which is executed by bash.

eog `curl 'http://xkcd.com/' | awk -F "ng): |</h" '/embedding/{print $2}'`
gwenview `wget -O - http://xkcd.com/ | grep 'png' | grep '<img src="http://imgs.xkcd.com/comics/' | sed s/title=\".*//g | sed 's/.png\"/.png/g' | sed 's/<img src=\"//g'`
2010-08-24 22:21:51
User: hunterm
Functions: grep sed
-1

Output the html from xkcd's index.html, filter out the html tags, and then view it in gwenview.

s="StrinG"; echo ${s,,}
2010-08-12 16:02:38
User: karpoke
Functions: echo
Tags: bash function
3

Another alternative is to define a function:

lower() {

echo ${@,,}

}

lower StrinG

__disown(){ local cmd=$1 ; shift ; $cmd "$@" &> /dev/null &disown }; for i in gvim ; do alias $i="__disown $i"; done
2010-07-07 20:46:45
User: smolav
Functions: alias shift
Tags: bash function
0

Define commands that you always invoke with an appended '&disown'. In the example:

gvim foo.txt

will open gvim dettached from the current terminal.

L(){ l=`builtin printf %${2:-$COLUMNS}s` && echo -e "${l// /${1:-=}}"; }
2

One of the first functions programmers learn is how to print a line. This is my 100% bash builtin function to do it, which makes it as optimal as a function can be. The COLUMNS environment variable is also set by bash (including bash resetting its value when you resize your term) so its very efficient. I like pretty-output in my shells and have experimented with several ways to output a line the width of the screen using a minimal amount of code. This is like version 9,000 lol.

This function is what I use, though when using colors or other terminal features I create separate functions that call this one, since this is the lowest level type of function. It might be better named printl(), but since I use it so much it's more optimal to have the name contain less chars (both for my programming and for the internal workings).

If you do use terminal escapes this will reset to default.

tput sgr0

For implementation ideas, check my

http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

addman () { export MANPATH=`find $1 -xdev -type d -name man -printf %p:`${MANPATH}; }
2010-06-12 17:47:20
User: zoomgarden
Functions: export man
Tags: man function
0

Prepends paths containing man directories to your MANPATH variable for the given top level directory. If you build or install software with non-standard documentation locations, you can just add them to your MANPATH with this little function. -xdev prevents crossing filesystem boundaries when searching for man dirs.