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).

Commands using zcat

Commands using zcat from sorted by
Terminal - Commands using zcat - 14 results
zcat `man -w manpage` | groff -mandoc -T html - > filename.html
2012-06-04 19:09:48
User: cassvin
Functions: groff zcat
0
Up
Down
save manpage as html file

The argument '-'(denote standard input) is optional.

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat log.tar.gz | grep -a -i "string"
2011-09-14 17:20:43
User: dycropts
Functions: grep zcat
0
Up
Down
grep compressed log files without extracting

Useful in system where log files are compressed for archival purposes

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat /usr/share/man/man1/man.1.gz | nroff -man | less
2011-09-07 01:13:57
User: atoponce
Functions: zcat
Tags: man less zcat nroff
0
Up
Down
Read manpages without the man(1) command

As odd as this may be, I know of servers where the man(1) command is not installed, and there is not enough room on / to install it. However, zcat(1), nroff(1) and less(1) are. This is a way to read those documents without the proper tool to do so, as sad as this may seem. :)

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat file.gz | less +/search_pattern
2011-01-14 21:29:40
User: gwchamb
Functions: less zcat
1
Up
Down
Quick searching with less

This command enables the user to append a search pattern on the command line when using less as the PAGER. This is especially convenient (as the example shows) in compressed files and when searching man pages (substituting the zcat command with man, however).

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat -f $(ls -tr access.log*)
2010-10-30 22:54:54
User: dooblem
Functions: ls zcat
Tags: logs zcat
1
Up
Down
concatenate compressed and uncompressed logs

with zcat force option it's even simpler.

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
find /var/log/apache2 -name 'access.log*gz' -exec zcat {} \; -or -name 'access.log*' -exec cat {} \;
2010-06-19 08:35:12
User: recursiverse
Functions: cat find zcat
0
Up
Down
concatenate compressed and uncompressed logs

This command allows you to stream your log files, including gziped files, into one stream which can be piped to awk or some other command for analysis.

Note: if your version of 'find' supports it, use:

find /var/log/apache2 -name 'access.log*gz' -exec zcat {} + -or -name 'access.log*' -exec cat {} +
Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat database.sql.gz | mysql -uroot -p'passwd' database
2010-03-23 12:41:57
User: foolano
Functions: zcat
Tags: mysql gzip zcat
5
Up
Down
Restore mysql database uncompressing on the fly.

This way you keep the file compressed saving disk space.

Other way less optimal using named pipes:

mysql -uroot -p'passwd' database <

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
( zcat $FILE || gzcat $FILE || bzcat2 $FILE ) | less
2010-03-17 03:14:48
User: DoNotRememberMe
Functions: zcat
5
Up
Down
Group OR'd commands where you expect only one to work

Something to stuff in an alias when you are working in multiple environments. The double-pipe OR will fall through until one of the commands succeeds, and the rest won't be executed. Any STDERR will fall out, but the STDOUT from the correct command will bubble out of the parenthesis to the less command, or some other command you specify.

Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
( 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
User: DoNotRememberMe
Functions: last ls read rm zcat
Tags: last command wtmp
5
Up
Down
See a full last history by expanding logrotated wtmp files

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.

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat access_log.*.gz | awk '{print $7}' | sort | uniq -c | sort -n | tail -n 20
2009-12-11 09:36:30
User: tkb
Functions: awk sort tail uniq zcat
Tags: log apache zcat analysis
4
Up
Down
Analyse compressed Apache access logs for the most commonly requested pages
Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
sudo zcat /var/log/auth.log.*.gz | awk '/Failed password/&&!/for invalid user/{a[$9]++}/Failed password for invalid user/{a["*" $11]++}END{for (i in a) printf "%6s\t%s\n", a[i], i|"sort -n"}'
2009-03-21 06:41:59
User: point_to_null
Functions: awk printf sudo zcat
Tags: Security awk brute force
21
Up
Down
Brute force discover

Show the number of failed tries of login per account. If the user does not exist it is marked with *.

Show sample output | Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat a_big_file.gz | sed -ne "$(zcat a_big_file.gz | tr -d "[:print:]" | cat -n | grep -vP "^ *\d+\t$" | cut -f 1 | sed -e "s/\([0-9]\+\)/\1=;\1p;/" | xargs)" | tr -c "[:print:]\n" "?"
2009-02-24 02:57:37
User: DEinspanjer
Functions: sed tr zcat
1
Up
Down
Scan a gz file for non-printable characters and display each line number and line that contains them.

Scans the file once to build a list of line numbers that contain non-printable characters

Scans the file again, passing those line numbers to sed as two commands to print the line number and the line itself. Also passes the output through a tr to replace the characters with a ?

Show sample output | Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat /usr/share/doc/vim-common/README.gz | vim -g +23 -
2009-02-16 01:25:37
User: int19h
Functions: vim zcat
1
Up
Down
Pipe a textfile to vim and move the cursor to a certain line

This command is more for demonstrating piping to vim and jumping to a specific line than anything else.

Exit vim with :q!

+23 jumps to line 23

- make vim receive the data from the pipe

Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
zcat /usr/share/man/man1/grep.1.gz | grep "color"
2009-02-04 09:38:45
User: root
Functions: grep zcat
-7
Up
Down
Search gzipped files

This decompresses the file and sends the output to STDOUT so it can be grepped. A good one to put in loops for searching directories of gzipped files, such as man pages.

Show sample output | Comments (2) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate