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.

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

Commands by penpen from sorted by
Terminal - Commands by penpen - 13 results
lynx http://shell-fu.org/
2009-08-20 11:47:35
User: penpen
-9

Today I learned that commandlinefu.com is not a alone in its conquest for further the knowledge about the command line. Allow me to introduce you to http://shell-fu.org/

host $HOSTNAME|cut -d' ' -f4
2009-08-08 12:39:00
User: penpen
Functions: cut host
1

Using DynDNS or a similar service not only allows access to your home machine from outside without needing to know what IP the ISP has assigned to it but it also comes in handy if you want to know your external IP address. The only purpose of the sed command is to remove the leading "host.na.me has address " part from the output. If you don't need to discard it you can simply use

host $HOSTNAME
~
2009-07-24 10:43:53
User: penpen
2

To change to $HOME in that manner you need to set a shell option. In zsh it is auto_cd, hence

setopt -o auto_cd

in bash4 it is autocd, hence

shopt -s autocd

What the option does is allow you to cd to a directory by just entering its name. This also works if the directory name is stored in a variable:

www=/var/www/lighttpd; $www

sends you to /var/www/lighttpd.

CAUTION: If a command or function name identical to the directory name exists it takes precedence.

for i in $(seq 1 11) 13 14 15 16; do man iso-8859-$i; done
2009-03-31 19:40:15
User: penpen
Functions: man seq
Tags: Linux unix
-2

Depending on the installation only certain of these man pages are installed. 12 is left out on purpose because ISO/IEC 8859-12 does not exist. To also access those manpages that are not installed use opera (or any other browser that supports all the character sets involved) to display online versions of the manpages hosted at kernel.org:

for i in $(seq 1 11) 13 14 15 16; do opera http://www.kernel.org/doc/man-pages/online/pages/man7/iso_8859-$i.7.html; done
wget --server-response --spider http://www.example.com/
2009-03-31 18:49:14
User: penpen
Functions: wget
5

Let me suggest using wget for obtaining the HTTP header only as the last resort because it generates considerable textual overhead. The first ellipsis of the sample output stands for

Spider mode enabled. Check if remote file exists.

--2009-03-31 20:42:46-- http://www.example.com/

Resolving www.example.com... 208.77.188.166

Connecting to www.example.com|208.77.188.166|:80... connected.

HTTP request sent, awaiting response...

and the second one looks for

Length: 438 [text/html]

Remote file exists and could contain further links,

but recursion is disabled -- not retrieving.

lynx -dump -head http://www.example.com/
2009-03-31 18:41:36
User: penpen
-1

Without the -dump option the header is displayed in lynx. You can also use w3m, the command then is

w3m -dump_head http://www.example.com/
rev <<< 'lorem ipsum' | tee /dev/stderr | rev
2009-03-31 13:12:09
User: penpen
Functions: rev tee
Tags: Linux unix
2

In the above example 'muspi merol' (the output of the first rev command) is sent to stderr and 'lorem ipsum' (the output of the second rev command) is sent to stdout. rev reverse lines of a file or files. This use of tee allows testing if a program correctly handles its input without using files that hold the data.

alias rot13="tr '[A-Za-z]' '[N-ZA-Mn-za-m]'"
2009-03-30 19:08:49
User: penpen
Functions: alias
Tags: Linux unix
9

rot13 maps a..mn..z (A..MN..Z) to n..za..m (n..za..m) and so does this alias.

watch -tn1 'bc<<<"`date -d'\''friday 21:00'\'' +%s`-`date +%s`"|perl -ne'\''@p=gmtime($_);printf("%dd %02d:%02d:%02d\n",@p[7,2,1,0]);'\'
2009-03-29 19:53:36
User: penpen
Functions: perl watch
Tags: Linux unix date
-2

An improved version of http://www.commandlinefu.com/commands/view/1772/simple-countdown-from-a-given-date that uses Perl to pretty-print the output. Note that the GNU-style '--no-title' option has been replaced by its one-letter counterpart '-t'.

scrot -e 'mv $f \$HOME/shots/; sitecopy -u shots; echo "\$BASE/$f" | xsel -i; feh `xsel -o`'
2009-03-26 12:08:39
User: penpen
Functions: echo
-1

Here $HOME/shots must exist and have appropriate access rights and sitecopy must be correctly set up to upload new screen shots to the remote site.

Example .sitecopyrc (for illustration purposes only)

site shots

server ftp.example.com

username user

password antabakadesuka

local /home/penpen/shots

remote public_html/shots

permissions ignore

The command uses scrot to create a screen shot, moves it to the screen shot directory, uploads it using screen uses xsel to copy the URL to the paste buffer (so that you can paste it with a middle click) and finally uses feh to display a preview of the screen shot.

Note that $BASE stands for the base URL for the screen shots on the remote server, replace it by the actual location; in the example http://www.example.com/~user/shots would be fitting.

Assign this command to a key combination or an icon in whatever panel you use.

scrot -e 'mv $f \$HOME/public_html/shots/; echo "http://\$HOSTNAME/~\$USER/shots/$f" | xsel -i; feh `xsel -o`'
2009-03-26 11:32:09
User: penpen
Functions: echo
0

A web server using $HOME/public_html as user directory is required, $HOME/public_html/shots must exist and have appropriate access rights and $HOSTNAME must be known to and accessible from the outside world.

The command uses scrot to create a screen shot, moves it to the screen shot directory, uses xsel to copy the URL to the paste buffer (so that you can paste it with a middle click) and finally uses feh to display a preview of the screen shot.

Assign this command to a key combination or an icon in whatever panel you use.

nc -l 8000
2009-03-25 23:09:38
User: penpen
Tags: Linux unix WWW
2

Have netcat listen on port 8000, point browser to http://localhost:8000/ and you see the information sent. netcat terminates as soon as your browser disconnects.

I tested this command on my Fedora box but linuxrawkstar pointed out that he needs to use

nc -l -p 8000

instead. This depends on the netcat version you use. The additional '-p' is required by GNU netcat that for example is used by Debian but not by the OpenBSD netcat port used by my Fedora system.

watch -n 1 :
2009-03-25 23:00:28
User: penpen
Functions: watch
Tags: Linux unix
-2

'watch' repeatedly (default every 2 seconds, -n 1 => every second) runs a command (here ':', a shorthand for 'true'), displays the output (here nothing) and the date and time of the last run.

I thought it to be obvious but it seemingly is not: to exit use Ctrl-C.