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Remove all backup files in my home directory

I use this simple command for remove all backup files generated usually by editors like Vim and Emacs.
This is sample output - yours may be different.
4

find ~user/ -name "*~" -exec rm {} \;

servermanaged · 2009-05-09 12:55:47 89
Get an IP address out of fail2ban jail

Removes an iptables rule created by fail2ban. This example shows how to remove a rule for an IP from the fail2ban-SSH chain. Can be used for any service monitored by fail2ban. For more on fail2ban, see http://www.fail2ban.org/wiki/index.php/Main_Page
This is sample output - yours may be different.
4

iptables -D fail2ban-SSH -s <ip_address_to_be_set_free> -j DROP

mheadd · 2009-05-08 19:22:15 3
Encrypted Tarballs

gpg's compression is as suitable as gzip's however your backups can now be encrypted. to extract use: gpg < folder.tpg | tar -xf -
This is sample output - yours may be different.
-1

tar -cf - folder/ | gpg -c > folder.tpg

copremesis · 2009-05-08 19:20:08 5
Safe Delete

remove file that has sensitive info safely. Overwrites it 33 times with zeros
This is sample output - yours may be different.
2

shred -n33 -zx file; rm file

copremesis · 2009-05-08 19:15:41 8
Remove unused libs/packages

deborphan(1) must be installed.
This is sample output - yours may be different.
0

aptitude remove $(deborphan)

P17 · 2009-05-08 18:51:51 7
en/decrypts files in a specific directory

To decrypt the files replace "ccenrypt" with "ccdecrypt. ccrypt(1) must be installed. It uses the AES (Rijndael) block cipher. To make it handier create an alias.
This is sample output - yours may be different.
4

for a in path/* ; do ccenrypt -K <password> $a; done

P17 · 2009-05-08 18:33:23 6
Edit a script that's somewhere in your path.

Often I need to edit a bash or perl script I've written. I know it's in my path but I don't feel like typing the whole path (or I don't remember the path).
This is sample output - yours may be different.
1

vim `which <scriptname>`

bunedoggle · 2009-05-08 17:21:47 6
Clears Firefox` cache without clicking around
This is sample output - yours may be different.
0

rm_cache() { rm -f $HOME/.mozilla/firefox/<profile>/Cache/* }; alias rmcache='rm_cache'

P17 · 2009-05-08 14:00:42 3
Go to the last directory invoked on command line

During this operation : # mv Joomla_1.5.10-Stable-Full_Package.zip /var/www/joomla/ I invoke /var/www/joomla/ as last command argument. To change in this directory I can use # cd !$ So I go to hob:/var/www/joomla#
This is sample output - yours may be different.
-3

cd !$

servermanaged · 2009-05-08 09:48:14 6
Generate padded numbers 001 002 ... 100
This is sample output - yours may be different.
0

echo 00{1..9} 0{10..99} 100

lv4tech · 2009-05-07 21:08:53 10
Search for files older than 30 days in a directory and list only their names not the full path
This is sample output - yours may be different.
2

find /var/www/html/ -type f -mtime +30 -exec basename {} \;

lv4tech · 2009-05-07 21:05:47 6
Find out which version of linux you are running
This is sample output - yours may be different.
-6

cat /etc/*issue

lv4tech · 2009-05-07 20:53:03 10
Execute multiple commands from history

Assuming that 219,229 and 221 are entries in history, I recall them in a single line for execute multiple commands 219 ifdown wlan0 ... 221 ifup wlan0 ... 229 iwconfig wlan0 mode Managed so the result is execution of # ifdown wlan0 ; iwconfig wlan0 mode Managed ; ifup wlan0
This is sample output - yours may be different.
8

!219 ; !229 ; !221

servermanaged · 2009-05-07 20:51:36 8
Follow the flow of a log file

tailf same as tail -f follow the flow of a log file, showing it in real time to stdout.
This is sample output - yours may be different.
5

tailf file.log

servermanaged · 2009-05-07 20:13:41 6
Search and replace in multiple files and save them with the same names - quickly and effectively!

Yeah, there are many ways to do that. Doing with sed by using a for loop is my favourite, because these are two basic things in all *nix environments. Sed by default does not allow to save the output in the same files so we'll use mv to do that in batch along with the sed. Show Sample Output
This is sample output - yours may be different.
```
No standard output on screen... just hit and boom. So, by the rule of the thumb first create a backup and then execute  or try to execute on some dummy files first.
```
-4

for files in $(ls -A directory_name); do sed 's/search/replaced/g' $files > $files.new && mv $files.new $files; done;

bassu · 2009-05-07 20:13:07 48
Find which version of Linux You are Running
This is sample output - yours may be different.
-4

lsb_release -d

tebeka · 2009-05-07 16:19:04 9
Ultra shortcut for ssh root@

When you have to manage lot of servers, it's boring to type ssh root@myhost for each connection. Now you can type juste "s someting" and you are connected. You can too add bash_completion script to complet with tab the name of your servers. This will be the next tips from me ;) Show Sample Output
This is sample output - yours may be different.
```
user@localhost:~$ s myhost
Last login: Mon May  4 15:16:18 2009 from 10.40.29.72
[root@myhost ~]#
```
-20

alias s='ssh -l root'

GouNiNi · 2009-05-07 15:57:12 11
Run a long job and notify me when it's finished

You will need libnotify-bin for this to work: sudo aptitude install libnotify-bin
This is sample output - yours may be different.
25

./my-really-long-job.sh && notify-send "Job finished"

root · 2009-05-07 15:50:27 16
Safely store your gpg key passphrase.

From time to time one forgets either thier gpg key or other passphrases. This can be very problematic in most cases. But luckily there's this script. Its based off of pwsafe which is a unix commandline program that manages encrypted password databases. For more info on pwsafe visit, http://nsd.dyndns.org/pwsafe/. What this script does is it will help you store all your passphrases for later on and allow you to copy it to your clipboard so you can just paste it in, all with one password. Pretty neat no? You can find future releases of this and many more scripts at The Teachings of Master Denzuko - denzuko.wordpress.com. Show Sample Output
This is sample output - yours may be different.
```
Enter passphrase for $HOME/.pwsafe.dat: _
```
0

pwsafe -qa "gpg keys"."$(finger `whoami` | grep Name | awk '{ print $4" "$5 }')"

denzuko · 2009-05-07 14:49:56 4
Expand shell variables in sed scripts

With this command you can use shell variables inside sed scripts. This is useful if the script MUST remain in an external file, otherwise you can simply use an inline -e argument to sed.
This is sample output - yours may be different.
-1

expanded_script=$(eval "echo \"$(cat ${sed_script_file})\"") && sed -e "${expanded_script}" your_input_file

giuseppe_rota · 2009-05-07 14:21:14 5
Random line from bash.org (funny IRC quotes)

bash.org is a collection of funny quotes from IRC. WARNING: some of the quotes contain "adult" jokes... may be embarrassing if your boss sees them... Thanks to Chen for the idea and initial version! This script downloads a page with random quotes, filters the html to retrieve just one liners quotes and outputs the first one. Just barely under the required 255 chars :) Improvment: You can replace the head -1 at the end by: awk 'length($0)>0 {printf( $0 "\n%%\n" )}' > bash_quotes.txt which will separate the quotes with a "%" and place it in the file. and then: strfile bash_quotes.txt which will make the file ready for the fortune command and then you can: fortune bash_quotes.txt which will give you a random quote from those in the downloaded file. I download a file periodically and then use the fortune in .bashrc so I see a funny quote every time I open a terminal. Show Sample Output
This is sample output - yours may be different.
```
<Lev> have you SEEN the people who wear the I LOVE LINUX T-shirts....that does more damage to the OS than a billion microsoft blue-screens
```
7

curl -s http://bash.org/?random1|grep -oE ".*.*"|grep -oE ""|sed -e 's/<\/p>/\n/g' -e 's///g' -e 's///g'|perl -ne 'use HTML::Entities;print decode_entities($_),"\n"'|head -1

Iftah · 2009-05-07 13:13:21 17
Which fonts are installed?

See all fonts installed in your system Show Sample Output
This is sample output - yours may be different.
```
Andale Mono
Arab
Arial
Arial Black
AR PL UMing CN
AR PL UMing HK
AR PL UMing TW
AR PL UMing TW MBE
Balker
Bitstream Charter
Bitstream Vera Sans
Bitstream Vera Sans Mono
Bitstream Vera Serif ....
```
5

fc-list | cut -d ':' -f 1 | sort -u

kayowas · 2009-05-07 12:57:58 15
Cloning hard disks over the network:

This is a bit to bit copy so if you have a 500GB hard disk it will take a long time even if have Gigabit Ethernet
This is sample output - yours may be different.
-1

Boot up destination machine with Knoppix live CD and run nc -l -p 9000 | dd of=/dev/sda Then on the master dd if=/dev/sda | nc <dest-ip> 9000 You can monitor bandwidth usage to see progress: nload eth0 -u M

lv4tech · 2009-05-07 05:26:58 6
Start a file browser in the current directory

This opens up nautilus in the current directory, which is useful for some quick file management that isn't efficiently done from a terminal.
This is sample output - yours may be different.
-10

screen -d -m nautilus --no-desktop `pwd`

windsurfer · 2009-05-07 00:49:07 14
sync a directory of corrupted jpeg with a source directory

Find all corrupted jpeg in the current directory, find a file with the same name in a source directory hierarchy and copy it over the corrupted jpeg file. Convenient to run on a large bunch of jpeg files copied from an unsure medium. Needs the jpeginfo tool, found in the jpeginfo package (on debian at least).
This is sample output - yours may be different.
0

for i in *jpg; do jpeginfo -c $i | grep -E "WARNING|ERROR" | cut -d " " -f 1 | xargs -I '{}' find /mnt/sourcerep -name {} -type f -print0 | xargs -0 -I '{}' cp -f {} ./ ; done

vincentp · 2009-05-07 00:30:36 4
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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 }

Speed up launch of liferea

If you use liferea frequently, you will see obvious speedup after you executed this command.

Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Have your sound card call out elapsed time.

Useful contexts : You are doing yoga or some other physical training in which you are holding a position. Or you practice the pomodoro productivity technique. Or your girlfriend said "We're leaving in 40 minutes". Design details: sleep executes before espeak to give you a 5 seconds head start. espeak is run in the background so it doesn't mess up the timing.

List your interfaces and MAC addresses

Requires sysfs mounted on /sys - may only be useful for Linux systems. Could also use "printf '%-8s %s\n' $(basename $f) $(cat $f/address)" instead of echo.

One command line web server on port 80 using nc (netcat)

Very simple web server listening on port 80 will serve index.html file or whatever file you like pointing your browser at http://your-IP-address/index.html for example. If your web server is down for maintenance and you'd like to inform your visitors about it, quickly and easily, you just have to put into the index.html file the right HTML code and you are done! Of course you need to be root to run the command using port 80.

calulate established tcp connection of local machine

If you want prepend/append text just wrap in echo: $echo Connected: `netstat -an|grep -ci "tcp.*established"`

Prepend a text to a file.

Using the sed -i (inline), you can replace the beginning of the first line of a file without redirecting the output to a temporary location.

Alias for lazy tmux create/reattach

summarize a list of IP addresses, verifying IP address and giving counts for each IP found

Working with lists of IP addresses it is sometimes useful to summarize a count of how many times an IP address appears in the file. This example, summarizeIP, uses another function "verifyIP" previously defined in commandlinefu.com to ensure only valid IP addresses get counted. The summary list is presented in count order starting with highest count.

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