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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 11:57:43 145
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 10:29:10 744
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 33
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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Check host port access using only Bash:

Create a transition between two videos

We take the first 50 frames of a.mp4 for track a, and 24 blank frames followed by b.mp4 for track b. We then create a transition from track a to track b starting from frame 25 and ending at frame 49. The output is stored in out.mp4 To view the results without saving remove "-consumer avformat:out.mp4" from the end. Documentation of the mlt framework and the melt command can be found here: http://www.mltframework.org/bin/view/MLT/Documentation

Optimize Xsane PDFs

Xsane produces PDFs that are too large - particularly multipage PDFs. This command compresses them. If you do not use A4, remove the -sPAPERSIZE flag.

Android PNG screenshot

Works with *rooted* Android devices. 400x800 are the screen dimensions of a typical handheld smartphone.

Perform sed substitution on all but the last line of input

In this simple example the command will add a comma to the end of every line except the last. I found this really useful when programatically constructing sql scripts. See sample output for example.

GREP a PDF file.

This is a good alternative to pdf2text for Ubuntu. To install it: sudo apt-get install python-pdfminer

Crash bash, in case you ever want to for whatever reason

This is a very hackish way to do it that I'm mainly just posting for fun, and I guess technically can more accurately be said to result in undefined behavior. What the command does is tell the shell to treat libpng like it's a shell plugin (which it's most certainly not) and attempt to install a "png_create_read" command from the library. It looks for the struct with the information about the command; since it's always the command name followed by "_struct", it'll look for a symbol called "png_create_read_struct". And it finds it, since this is the name of one of libpng's functions. But bash has no way to tell it's a function instead of a struct, so it goes ahead and parses the function's code as if it was command metadata. Inevitably, bash will attempt to dereference an invalid pointer or whatever, resulting in a segfault.

Convert CSV to JSON

Replace 'csv_file.csv' with your filename.

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

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