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commandlinefu.com is the place to record those command-line gems that you return to again and again.

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May 19, 2015 - A Look At The New Commandlinefu
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All commands from sorted by
Terminal - All commands - 12,408 results
dd if=/dev/zero of=junk bs=1M count=1K
2009-11-01 23:45:51
User: guedesav
Functions: dd
Tags: dd ram rm
-11

This is an useful command for when your OS is reporting less free RAM than it actually has. In case terminated processes did not free their variables correctly, the previously allocated RAM might make a bit sluggis over time.

This command then creates a huge file made out of zeroes and then removes it, thus freeing the amount of memory occupied by the file in the RAM.

In this example, the sequence will free up to 1GB(1M * 1K) of unused RAM. This will not free memory which is genuinely being used by active processes.

curl ip.appspot.com
2009-10-31 21:11:10
User: ktoso
23

Yeah I know it's been up here a million times, but this service is a really clean and nice one. Nothing but your IP address on it. Actually I was to write something like this, and noticed this on appspot... ;)

mplayer test.mp3 < /dev/null & mplayer test.avi -nosound -speed 1.0884
2009-10-31 09:33:33
User: fxj
1

Sometimes audio and video are not sync'ed. The factor 1.0884 is the quotient 48000/44100. One mplayer plays the audio file in the background, the other the video in the foreground. You can dump the audio file before with another commandlinefu

path+=( /sbin /usr/sbin /usr/local/sbin ); path=( ${(u)path} );
2009-10-31 02:32:25
User: atoponce
Tags: sudo zsh PATH sbin
0

On RHEL, Fedora and CentOS systems, and maybe others, the sbin directories aren't in the user's $PATH. For those systems that use 'sudo', this can be inconvenient typing the full path all the time. As a result, you can easily take advantage of adding the sbin directories to your PATH by adding this simple line to you .zshrc.

mpc play $(sed -n "s@^[ >]\([0-9]\+\)) $(mpc playlist|cut -d' ' -f3-|dmenu -i -p 'song name'||echo void)@\[email protected]" < <(mpc playlist))
2009-10-30 16:22:10
User: gibboris
Functions: sed
1

Add a [fluxbox] binding in your key file then this

command provides a dmenu selector for the next track to play

for x in `find /vmfs/volumes/ -name *vmx -exec grep -H linux.iso {} \; |cut -d : -f 1`; do echo $x; grep -i sync $x; done;
2009-10-30 16:19:16
User: uid0
Functions: cut echo grep sync
0

besure to adjust your find to use to correct location of your VMX files.

alias whatismyip="wget -q -O - http://whatismyip.com/automation/n09230945.asp"
2009-10-30 15:42:52
User: gibboris
Functions: alias
-3

The preferred way for scripts (and easier to parse)

dh() { du -ch --max-depth=1 "${@-.}"|sort -h }
unzip -l <filename>
2009-10-30 12:21:06
User: tatwright
-8

This is useful for working out whether the file that you are unzipping is an evil zip file which will create 200 new files in your current direction

for URL in `wget -O - http://api.flickr.com/services/feeds/photos_public.gne?tags=bitch,bw 2>/dev/null | grep -E -o "http[^ ]+?jpg" | grep -v "_m" | uniq | grep -v 'buddy' `; do FILE=`echo $URL | grep -E -o "[0-9a-z_]+\.jpg"`; curl $URL > $FILE; done;
alias ..="cd .."; alias ...="cd ../.."; alias ....="cd ../../.."
2009-10-30 01:04:33
User: Tzunamii
Functions: alias
Tags: cd
1

Change to your taste. Much quicker than having to add 'cd' every time. Add it to your .bashrc or .bash_profile.

cd() { if [[ "$1" =~ ^\.\.+$ ]];then local a dir;a=${#1};while [ $a -ne 1 ];do dir=${dir}"../";((a--));done;builtin cd $dir;else builtin cd "$@";fi ;}
2009-10-29 21:43:51
User: eightmillion
Functions: cd
Tags: cd
4

This is a kind of wrapper around the shell builtin cd that allows a person to quickly go up several directories.

Instead of typing:

cd ../..

A user can type:

cd ...

Instead of:

cd ../../..

Type:

cd ....

Add another period and it goes up four levels. Adding more periods will take you up more levels.

cat > list -
2009-10-29 20:20:11
Functions: cat
3

Quick write some notes to a file with cat. Ctrl+C when you have finish.

nice -n19 dump -0af - /<filesystem> -z9|gpg -e -r <gpg key id>|cstream -v 1 -t 60k|ssh <[email protected]> "cat > backup.img"
2009-10-29 18:27:25
User: din7
Functions: dump gpg nice ssh
2

This command will nicely dump a filesystem to STDOUT, compress it, encrypt it with the gpg key of your choice, throttle the the data stream to 60kb/s and finally use ssh to copy the contents to an image on a remote machine.

newest () { candidate=''; for i in "$@"; do [[ -f $i ]] || continue; [[ -z $candidate || $i -nt $candidate ]] && candidate="$i"; done; echo "$candidate"; }
2009-10-29 17:35:01
User: johnraff
Functions: echo
Tags: bash files
1

Usage example:

newest Desktop/*

Replace "-nt" with "-ot" for oldest.

Run

shopt -s dotglob

first to include dotfiles.

sudo touch /forcefsck
2009-10-29 17:04:47
User: johnraff
Functions: sudo touch
38

The empty file /forcefsck causes the file system check fsck to be run next time you boot up, after which it will be removed.

This works too:

sudo >/forcefsck
find . -type f -size 0 -delete
2009-10-29 16:51:09
User: Skam
Functions: find
1

The command find search commands with size zero and erase them.

echo {001..5}
2009-10-29 16:25:44
User: nanard06
Functions: echo
Tags: bash
6

bash2 : for X in $(seq 1 5); do printf "%03g " "$X";done

bash3 : for X in {1..5}; do printf "%03g " "$X";done

bash4 : echo {001..5}

> [filename].txt
2009-10-29 16:20:35
User: felix001
0

empties a file...

--- fir3net.com ---

find . -size 0 -exec rm '{}' \;
<alt+q>
2009-10-29 14:55:12
User: luther
Tags: edit zsh
5

When writing on the command line of zsh, by pressing Alt+q the command will be cleaned, and you can insert another one. The command you were writing will be recorder, and pasted on the prompt immediately after the "interrupting" command is inserted.

find . -size 0 -print0 | xargs -0 rm
2009-10-29 14:10:02
User: osvaldofilho
Functions: find xargs
-1

The command find search commands with size zero and erase them.

mysql -u <user> --password=<password> -e "SHOW COLUMNS FROM <table>" <database> | awk '{print $1}' | tr "\n" "," | sed 's/,$//g'
2009-10-29 13:42:17
User: maxmanders
Functions: awk sed tr
-1

Useful when you need to write e.g. an INSERT for a table with a large number of columns. This command will retrieve the column names and comma-separate them ready for INSERT INTO(...), removing the last comma.

ps -eo user,pcpu,pmem | tail -n +2 | awk '{num[$1]++; cpu[$1] += $2; mem[$1] += $3} END{printf("NPROC\tUSER\tCPU\tMEM\n"); for (user in cpu) printf("%d\t%s\t%.2f\t%.2f\n",num[user], user, cpu[user], mem[user]) }'
2009-10-29 12:49:01
User: georgz
Functions: awk ps tail
7

The original version gives an error, here is the correct output

(crontab -e) 00 12 * * * apt-get update (/etc/init.d/cron restart)