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Replaces every ocurrences of 'old' for 'new' in all files specified

Replaces every ocurrence of 'old' for 'new' in all files specified. After the 'i' char you can put a '~' or whatever to create a backup file for each replaced with the name equal to the original plus character.
This is sample output - yours may be different.
0

perl -i -pe "s/old/new/g" *

pandres · 2009-02-05 12:07:27 66
cycle through a 256 colour palette

just for fun
This is sample output - yours may be different.
14

yes "$(seq 232 255;seq 254 -1 233)" | while read i; do printf "\x1b[48;5;${i}m\n"; sleep .01; done

pixelbeat · 2009-02-05 12:01:37 25
Serve current directory tree at http://$HOSTNAME:8000/
This is sample output - yours may be different.
846

python -m SimpleHTTPServer

pixelbeat · 2009-02-05 11:57:43 146
Shows the largest files in your archives
This is sample output - yours may be different.
0

tar -tvjf backup.tar.bz2 | sort -nrk 3 | head

Sekenre · 2009-02-05 11:57:18 89
Remove invalid host keys from ~/.ssh/known_hosts

Useful if you have to tunnel ssh through a local port and it complains of the host key being different. Much easier than manually editing the file.
This is sample output - yours may be different.
9

ssh-keygen -R \[localhost\]:8022

Sekenre · 2009-02-05 11:48:09 113
find all processes named hunger and force kill, minus the grep itself and output to a file called fu.bar
This is sample output - yours may be different.
-3

ps -auwx|egrep hunger|grep -v grep| awk '{print "kill -9",$1}' > ~/fu.bar

lendellray · 2009-02-05 11:43:38 30
rgrep: recursive grep without .svn

Only excludes .svn from filenames. Show Sample Output
This is sample output - yours may be different.
```
[nf@dev ~/css]$ rgrep sprites
./template.php:require "css_sprites.php";
./template.php: $abs_path.'/sprites/',
./template.php: 'sprites.css',
./template.php:include 'sprites.css';
```
2

alias rgrep="find . $ ! -name .svn -o -prune $ -type f -print0 | xargs -0 grep"

nf · 2009-02-05 11:23:23 34
Get the 10 biggest files/folders for the current direcotry
This is sample output - yours may be different.
51

du -s * | sort -n | tail

bambambazooka · 2009-02-05 11:18:43 33
Start urxvt and do whatever is needed to open the screen session named "main"

Open a terminal (urxvt in this case) to connect to a screen session (named "main") and create the screen session if necessary.
This is sample output - yours may be different.
0

screen -ls | grep main && urxvt -name screen -e screen -x main || urxvt -name screen -e screen -R -S main

trey · 2009-02-05 10:51:31 191
SSH to a machine's internet address if it is not present on your local network

Ping machine once, waiting 1 second for response until failing. Upon fail, ssh globally, otherwise ssh locally.
This is sample output - yours may be different.
1

ping localip -c 1 -W 1 &> /dev/null && ssh localip || ssh globalip

trey · 2009-02-05 10:40:26 524
search the manual page names and descriptions
This is sample output - yours may be different.
2

apropos somekeyword

chrisdrew · 2009-02-05 10:29:15 57
locate bin, src, and man file for a command
This is sample output - yours may be different.
4

whereis somecommand

chrisdrew · 2009-02-05 10:29:10 761
locate a command

Returns the pathnames of the files which would be executed in the current environment had its arguments been given as a command.
This is sample output - yours may be different.
0

which somecommand

chrisdrew · 2009-02-05 10:29:04 41
Search through files, ignoring .svn

Variant of find grep that ignores files with .svn in the name. Useful for searching through a local repository of source code.
This is sample output - yours may be different.
-2

find . -type f -print0 | grep -vzZ '.svn' | xargs -0 grep --color -nEHi "SEARCHTERM"

troelskn · 2009-02-05 10:27:15 39
cd canonical (resolve any symlinks)
This is sample output - yours may be different.
-1

alias cdc='cd `pwd -P`'

adavies42 · 2009-02-05 10:15:11 36
ring the bell
This is sample output - yours may be different.
3

alias beep='echo -en "\007"'

adavies42 · 2009-02-05 10:14:24 34
get a directory from one machine to another using tar and ssh
This is sample output - yours may be different.
3

ssh somemachine "cd some dir; tar zcpf - somedirname" |tar zxpf -

mischamolhoek · 2009-02-05 09:10:56 30
A nice command for summarising repeated information
This is sample output - yours may be different.
4

alias counts=sort | uniq -c | sort -nr

porges · 2009-02-05 08:24:02 519
Rip audio from a video file.

Replace and accordingly.
This is sample output - yours may be different.
68

mplayer -ao pcm -vo null -vc dummy -dumpaudio -dumpfile <output-file> <input-file>

sykora · 2009-02-05 08:17:04 40
diff two unsorted files without creating temporary files

bash/ksh subshell redirection (as file descriptors) used as input to diff
This is sample output - yours may be different.
100

diff <(sort file1) <(sort file2)

systemj · 2009-02-04 22:20:13 502
Run a command only when load average is below a certain threshold

Good for one off jobs that you want to run at a quiet time. The default threshold is a load average of 0.8 but this can be set using atrun. Show Sample Output
This is sample output - yours may be different.
```
job 6 at 2009-02-04 19:03
```
45

echo "rm -rf /unwanted-but-large/folder" | batch

root · 2009-02-04 19:07:52 45
Get the full path to a file

Useful in scripts when the file is passed in as an argument. Eg. filepath=$(realpath $1) Show Sample Output
This is sample output - yours may be different.
```
/full/path/to/examplefile.txt
```
7

realpath examplefile.txt

root · 2009-02-04 15:41:44 46
Compare a remote file with a local file

Useful for checking if there are differences between local and remote files.
This is sample output - yours may be different.
176

ssh user@host cat /path/to/remotefile | diff /path/to/localfile -

root · 2009-02-04 11:33:19 79

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

-7

zcat /usr/share/man/man1/grep.1.gz | grep "color"

root · 2009-02-04 09:38:45 54

Display all readline binding that use CTRL

Useful for getting to know the available keyboard shortcuts. Show Sample Output

bind -p | grep -F "\C"

root · 2009-02-03 16:22:14 57

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Clean swap area after using a memory hogging application

When you run a memory intensive application (VirtualBox, large java application, etc) swap area is used as soon as memory becomes insufficient. After you close the program, the data in swap is not put back on memory and that decreases the responsiveness. Swapoff disables the swap area and forces system to put swap data be placed in memory. Since running without a swap area might be detrimental, swapon should be used to activate swap again. Both swapoff and swapon require root privileges.

Block all IP addresses and domains that have attempted brute force SSH login to computer

I use iptables. To rate limit connections. Very easy and no ban lists to manage.

Execute a command with a timeout

I like much more the perl solution, but without using perl. It launches a backgroup process that will kill the command if it lasts too much. A bigger function: check_with_timeout() { [ "$DEBUG" ] && set -x COMMAND=$1 TIMEOUT=$2 RET=0 # Launch command in backgroup [ ! "$DEBUG" ] && exec 6>&2 # Link file descriptor #6 with stderr. [ ! "$DEBUG" ] && exec 2> /dev/null # Send stderr to null (avoid the Terminated messages) $COMMAND 2>&1 >/dev/null & COMMAND_PID=$! [ "$DEBUG" ] && echo "Background command pid $COMMAND_PID, parent pid $$" # Timer that will kill the command if timesout sleep $TIMEOUT && ps -p $COMMAND_PID -o pid,ppid |grep $$ | awk '{print $1}' | xargs kill & KILLER_PID=$! [ "$DEBUG" ] && echo "Killer command pid $KILLER_PID, parent pid $$" wait $COMMAND_PID RET=$? # Kill the killer timer [ "$DEBUG" ] && ps -e -o pid,ppid |grep $KILLER_PID | awk '{print $1}' | xargs echo "Killing processes: " ps -e -o pid,ppid |grep -v PID | grep $KILLER_PID | awk '{print $1}' | xargs kill wait sleep 1 [ ! "$DEBUG" ] && exec 2>&6 6>&- # Restore stderr and close file descriptor #6. return $RET }

Extract audio from Mythtv recording to Rockbox iPod using ffmpeg

There are some pretty good live performances on late night TV. With Mythtv I record David Letterman, Jimmy Fallon, and Conan nightly all in HD from over the air broadcasts. If I find a live performance I like I copy it to my Rockboxed iPod using this command. The Rockbox firmware knows how to downmix 5.1 audio. The command above extracts the audio from the video starting at 58 minutes and 15 seconds. It ends at the end of the file since this was the last performance of the recording. The command creates an ac3 file. I copy the ac3 file to my Rockbox iPod and rock on.

automount samba shares as devices in /mnt/

the middle command between the ; and ; is the vi commands that insert that line into the last line of the file, the esc with the carets is literally hitting the escape key, you have to have the smbfs package installed to do it, I use it to access my iTunes music on my mac from my linux PC's with amarok so I can play the music anywhere in the house. among other things, it allows you to access the files on that share from your computer anytime you're on that network.

Format partition with ext4 but without a journal

For slow flash memory (cheap thumb drive), ext4 is the fastest stable file system for all use cases with no relevant exception: http://www.linuxplanet.com/linuxplanet/tutorials/7208/1 Since we can usually dispense with the benefits of a journal for this type of storage, this is a way to achieve the least awful I/O-speed. Disabling the journal for an existing ext4 partition can be achieved using $ tune2fs -O ^has_journal /dev/sdXN Note that it is often recommended to format removable flash media with ext2, due to the lack of a journal. ext4 has many advantages over ext2 even without the journal, with much better speed as one of the consequences. So the only usecase for ext2 would be compatibility with very old software.

Remove all unused kernels with apt-get

Note the double space: "...^ii␣␣linux-image-2..." Like 5813, but fixes two bugs: [1]This leaves the meta-packages 'linux-headers-generic' and 'linux-image-generic' alone so that automatic upgrades work correctly in the future. [2]Kernels newer than the currently running one are left alone (this can happen if you didn't reboot after installing a new kernel). I'm bummed that this took 228 characters. I'd like to see a simpler version.

download 10 random wallpapers from google

you may want &hl=en for &hl=es for the language you may want imgsz=xxlarge for imgsz=large or whatever filter you may want q=apples or whatever

Runs previous command replacing foo by bar every time that foo appears

Very useful for rerunning a long command changing some arguments globally. As opposed to ^foo^bar, which only replaces the first occurrence of foo, this one changes every occurrence.

Grab a list of MP3s out of Firefox's cache

Ever gone to a site that has an MP3 embedded into a pesky flash player, but no download link? Well, this one-liner will yank the names of those tunes straight out of FF's cache in a nice, easy to read list. What you do with them after that is *ahem* no concern of mine. ;)

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