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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.




Commands using grep from sorted by
Terminal - Commands using grep - 1,565 results
ls -1 /bin | xargs -l1 whatis 2>/dev/null | grep -v "nothing appropriate"
2009-02-17 14:46:01
User: stinger
Functions: grep ls whatis xargs

Get simple description on each file from /bin dir, in list form, usefull for newbies.

grep -c -e '^cpu[0-9]\+' /proc/stat
find /directory/to/search/ -type f -print0 | xargs -0 grep "findtext"
2009-02-17 07:16:32
User: dingobytes
Functions: find grep xargs

this will find text in the directory you specify and give you line where it appears.

grep "processor" /proc/cpuinfo | wc -l
2009-02-17 05:39:49
User: jbcurtis
Functions: grep wc

/proc/cpuinfo contains information about the CPU.

Search for "processor" in the /proc/cpuinfo file

wc -l, counts the number of lines.

grep -sq "" /etc/lsb-release && lsb_release -rd
2009-02-17 05:21:20
User: int19h
Functions: grep

grep -sq "" filename && command

grep can be used in combination with && to run a command if a file exists.

ps aux | grep "[s]ome_text"
2009-02-17 02:10:50
User: SiegeX
Functions: grep ps

The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE.

grep -v "^\($\|#\)" <filenames>
2009-02-16 21:40:09
User: raphink
Functions: grep

Filter comments and empty lines in files. I find this very useful when trying to find what values are actually set in a very long example config file.

I often set an alias for it, like :

alias nocomment='grep -v "^\($\|#\)"'

cd /usr/ports; grep -F "`for o in \`pkg_info -qao\` ; \ do echo "|/usr/ports/${o}|" ; done`" `make -V INDEXFILE` | \ grep -i \|ports@freebsd.org\| | cut -f 2 -d \|
2009-02-16 21:07:35
User: grep
Functions: cd cut grep

only works for freeBSD where ports are installed in /usr/ports

credit to http://wiki.freebsd.org/PortsTasks

newhostname=$(hostname | awk -F. '{print $1 "." $2}'); ipaddress=$(nslookup `hostname` | grep -i address | awk -F" " '{print $2}' | awk -F. '{print $3 "." $4}' | grep -v 64.142);PS1="[`id -un`.$newhostname.$ipaddress]"' (${PWD}): '; export PS1
2009-02-16 20:11:53
User: simardd

changes the PS1 to something better than default.

[username.hostname.last-2-digits-of-ip] (current directory)

df / | awk '{print $1}' | grep dev | xargs tune2fs -l | grep create
2009-02-16 18:45:03
User: Kaio
Functions: awk df grep tune2fs xargs

Very useful set of commands to know when your file system was created.

find . -name "*.jar" | xargs -tn1 jar tvf | grep --color "SearchTerm"
2009-02-16 17:18:36
Functions: find grep xargs

Great for finding which jar some pesky class is hiding in!

for I in `echo "show databases;" | mysql | grep -v Database`; do mysqldump $I > "$I.sql"; done
2009-02-16 16:41:05
User: ruedu
Functions: grep

Backups all MySQL databases to individual files. Can be put into a script that grabs current date so you have per day backups.

ip route | grep default | awk '{print $3}'
2009-02-16 16:29:03
User: ruedu
Functions: awk grep route

This gets you your default route programatically, useful for scripts

LC_ALL=C svn info | grep Revision | awk '{print $2}'
2009-02-16 14:53:52
Functions: awk grep info

This is the simple revision number on stdout, that can be fed to any useful/fun script of yours. Setting LC_ALL is useful if you use another locale, in which case "Revision" is translated and cannot be found. I use this with doxygen to insert my source files revisions into the doc. An example in Doxyfile:

FILE_VERSION_FILTER = "function svn_filter { LC_ALL=C svn info $1 | grep Revision | awk '{print $2}'; }; svn_filter"

Share your ideas about what to do with the revision number !

iptables -L -n --line-numbers | grep xx.xx.xx.xx
2009-02-16 13:38:05
User: nullrouter
Functions: grep iptables

This is just one method of checking to see if an IP is blocked via IP tables or CSF. Simple and to the point. Replace xx.xx.xx.xx with the IP you wish to check.

for i in $(svn st | grep "?" | awk '{print $2}'); do svn add $i; done;
find . -type f -name '*.html' -exec grep -H HACKED {} \; > hacklog.txt
2009-02-16 08:57:25
User: nullrouter
Functions: find grep

This will check all .HTML file contents for the word "Hacked" and dump it to hacklog.txt. This is great for located all those files affected by nasty Joomla exploits. Change the .HTML to any other extension you wish to check, and of course the word "HACKED" for other searches.

netstat -anl | grep :80 | awk '{print $5}' | cut -d ":" -f 1 | uniq -c | sort -n | grep -c IPHERE
2009-02-16 08:54:08
User: nullrouter
Functions: awk cut grep netstat sort uniq

This will tell you who has the most Apache connections by IP (replace IPHERE with the actual IP you wish to check). Or if you wish, remove | grep -c IPHERE for the full list.

netstat -pant 2> /dev/null | grep SYN_ | awk '{print $5;}' | cut -d: -f1 | sort | uniq -c | sort -n | tail -20
2009-02-16 08:49:38

List top 20 IP from which TCP connection is in SYN_RECV state.

Useful on web servers to detect a syn flood attack.

Replace SYN_ with ESTA to find established connections

find . -type f -exec grep -l pattern {} \; | xargs vi +/pattern
find . -type f -exec grep -l XXX {} \;|tee /tmp/fileschanged|xargs perl -pi.bak -e 's/XXX/YYY/g'
2009-02-16 02:55:23
User: drossman
Functions: find grep perl tee xargs

Find all files that contain string XXX in them, change the string from XXX to YYY, make a backup copy of the file and save a list of files changed in /tmp/fileschanged.

ls -F | grep '\''\*'\'' | sed '\''s/\*$//'\
strings /dev/urandom | grep -o '[[:alnum:]]' | head -n 30 | tr -d '\n'; echo
2009-02-16 00:39:28
User: jbcurtis
Functions: grep head strings tr

Find random strings within /dev/urandom. Using grep filter to just Alphanumeric characters, and then print the first 30 and remove all the line feeds.

dd bs=1 count=32 if=/dev/random 2> /dev/null | md5 | grep -o '\w*'
ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^/ /' -e 's/-/|/'
2009-02-15 20:43:21
Functions: grep ls sed

Prints a graphical directory tree from your current directory