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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 10:29:10 749
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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Determine an image's dimensions

Simple use of ImageMagick identify function.

Search for an active process without catching the search-process

This does the same thing as many of the 'grep' based alternatives but allows a more finite control over the output. For example if you only wanted the process ID you could change the command: $ ps -ef | awk '/mingetty/ && !/awk/ {print $2}' If you wanted to kill the returned PID's: $ ps -ef | awk '/mingetty/ && !/awk/ {print $2}' | xargs -i kill {}

syncronizing datas beetween two folder (A and B) excluding some directories in A (dir1 and dir2)

Get AWS temporary credentials ready to export based on a MFA virtual appliance

You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Convert seconds to [DD:][HH:]MM:SS

Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Remote Serial connection redirected over network using SSH

Requires software found at: http://lpccomp.bc.ca/remserial/ Remote [A] (with physical serial port connected to device) $./remserial -d -p 23000 -s "115200 raw" /dev/ttyS0 & Local [B] (running the program that needs to connect to serial device) Create a SSH tunnel to the remote server: $ssh -N -L 23000:localhost:23000 user@hostwithphysicalserialport Use the locally tunnelled port to connect the local virtual serial port to the remote real physical port: $./remserial -d -r localhost -p 23000 -l /dev/remser1 /dev/ptmx & Example: Running minicom on machine B using serial /dev/remser1 will actually connect you to whatever device is plugged into machine A's serial port /dev/ttyS0.

rsync Command that limits bandwidth

Useful for transferring large file over a network during operational hours

rsync directory tree including only files that match a certain find result.

'-mtime -10' syncs only files newer 10 days (-mtime is just one example, use whatever find expressions you need) printf %P: File's name with the name of the command line argument under which it was found removed. this way, you can use any src directory, no need to cd into your src directory first. using \\0 in printf and a corresponding --from0 in rsync ensures that even filenames with newline characters work (thanks syssyphus for #3808). both, #1481 and #3808 just work if you either copy the current directory (.) , or the filesystem root (/), otherwise the output from find and the source dir from rsync just don't match. #7685 works with an arbitrary source directory.

get time in other timezones

On Ubuntu, if tzwatch is installed, then you can call up in terminal the output for every time zone configured in gWorldClock.

Save a file you edited in vim without the needed permissions

probably just like 1204, but uses tee as a filter (+ I actually understand how this one works)

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