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Remove all files previously extracted from a tar(.gz) file.

xargs deals badly with special characters (such as space, ' and "). To see the problem try this: touch important_file touch 'not important_file' ls not* | xargs rm Parallel https://savannah.nongnu.org/projects/parallel/ does not have this problem.
This is sample output - yours may be different.
-2

tar -tf <file.tar.gz> | parallel rm

unixmonkey8046 · 2010-01-28 08:28:16 3
run command on a group of nodes in parallel

Parallel is from https://savannah.nongnu.org/projects/parallel/ Other examples would be: (echo foss.org.my; echo www.debian.org; echo www.freenetproject.org) | parallel traceroute seq -f %04g 0 9999 | parallel -X rm pict{}.jpg
This is sample output - yours may be different.
3

seq 1 5 | parallel ssh {}.cluster.net uptime

unixmonkey8046 · 2010-01-28 08:18:50 6
Autodetect screens and extend workspace to the left

Disper: http://willem.engen.nl/projects/disper/ Moving Gnome Panels to the external screen is done using gconf-editor, changing property "/apps/panel/toplevels/top_panel_screen0/monitor", as well as "/apps/panel/toplevels/bottom_panel_screen0/monitor" to int value "1". This can be done from the command line using ' gconftool-2 --set "/apps/panel/toplevels/top_panel_screen0/monitor" --type integer "1"' so a nice script can be written.
This is sample output - yours may be different.
-1

disper --displays=auto -e -t left

unixmonkey6754 · 2010-01-28 06:46:56 113
Insert the last argument of the previous command
This is sample output - yours may be different.
2

<ALT> .

fraktil · 2010-01-28 03:33:31 5
Press a key automatically

Press a key automatically via xvkbd.
This is sample output - yours may be different.
1

while true; do xvkbd -xsendevent -text "\[$KEY]" && sleep 2; done

matthewbauer · 2010-01-28 03:11:10 14
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.
This is sample output - yours may be different.
3

/usr/sbin/iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent -set

jeffatrackaid · 2010-01-28 00:51:49 3
Extract names and email addresses from LDIF files
This is sample output - yours may be different.
0

grep -E '^(cn|mail):' file.ldif | sed -e 's/^[a-z]*: //'

linuxnetbook · 2010-01-27 22:29:02 4
Erase a word
This is sample output - yours may be different.
6

<CTRL+w>

jslopez · 2010-01-27 22:13:29 25
Erase a word

hit BACKSPACE more than once to delete more words Show Sample Output
This is sample output - yours may be different.
```
$ echo something
<ALT> <BACKSPACE>
$ echo
```
2

<ALT> <BACKSPACE>

wincus · 2010-01-27 19:52:51 4
MAC OS X: audible notification after a long command

I often run some command that takes a while to finish. By putting the say command afterward, I get an audio notification. Please note that this command (say) only works on Mac OS X and not Linux.
This is sample output - yours may be different.
-2

long_command; say I am all done

haivu · 2010-01-27 19:03:01 12
Shell function to create a directory named with the current date, in the format YYYYMMDD.

Creates a directory named with the current date, in the format YYYYMMDD. If you give it a directory name as an argument, it will create the new directory inside the specified directory. This is an alternative to command #1993. Show Sample Output
This is sample output - yours may be different.
```
$ # in '.'
$ dmd
$ ls -l
drwxr-xr-x 2 bchittenden bchittenden 4096 2010-01-27 10:26 20100127
$ # in 'test/asdf/'
$ mkdir -p test/asdf
$ dmd test/asdf
$ ls -l test/asdf
drwxr-xr-x 2 bchittenden bchittenden 4096 2010-01-27 10:29 20100127
```
1

dmd () { ( if [ "$1"x != "x" ]; then cd $1; fi; mkdir `date +%Y%m%d` ) }

bartonski · 2010-01-27 15:53:26 5
Do some Perl learning...

Prerequisites: module Pod::Webserver installed. You can install it typing: sudo perl -MCPAN -e 'install Pod::Webserver' You can replace elinks with your fav browser. For FF: podwebserver& sleep 2; firefox -remote 'openurl( http://127.0.0.1:8020/, new-tab )' If you have Firefox open, this will pop-up the index web in a new tab.
This is sample output - yours may be different.
5

podwebserver& sleep 2; elinks 'http://127.0.0.1:8020'

vlan7 · 2010-01-27 10:57:34 13
Using numsum to sum a column of numbers.

if you, like me, do not have the numsum, this way can do the same. Show Sample Output
This is sample output - yours may be different.
```
1653
```
1

echo $(( $( cat count.txt | tr "\n" "+" | xargs -I{} echo {} 0 ) ))

glaudiston · 2010-01-27 10:02:30 4
Simple Gumblar check command
This is sample output - yours may be different.
1

find filepath -type f -iname "*.html" -o -iname "*.htm" -o -iname "*.php" | xargs grep "Exception\|LGPL\|CODE1"

negima · 2010-01-27 08:43:24 3

Gathering all MAC's in your local network

replace eth0 with your ethernet or wireless network interface. Show Sample Output

sudo arp-scan --interface=eth0 -l

alamati · 2010-01-27 05:36:48 3

delete multiple files with spaces in filenames (with confirmation)

ls -Q will show the filenames in quotes. xargs -p rm will print all the filenames piped from ls -Q and ask for confirmation before deleting the files. without the -Q switch, if we have spaces in names, then the files won't be deleted. Show Sample Output
This is sample output - yours may be different.
```
ls -Q *
"new file"  "new file (another copy)"  "new file (copy)"

ls -Q * | xargs -p rm
rm new file new file (another copy) new file (copy) ?...y
```
1

ls -Q * | xargs -p rm

temp_reg · 2010-01-27 02:46:49 9
Find the fastest server to disable comcast's DNS hijacking

Comcast is an ISP in the United States that has started hijacking DNS requests as a "service" for its customers. For example, in Firefox, one used to be able to do a quick "I'm Feeling Lucky" Google search by typing a single word into the URL field, assuming the word is not an existing domain when surrounded by www.*.com. Comcast customers never receive the correct NX (non-existent domain) error from DNS. Instead, they are shown a page full of advertising. There is a way to "opt out" from their service, but that requires having the account password and the MAC address of your modem handy. For me, it was easier just to set static DNS servers. But the problem is, which ones to choose? That's what this command answers. It'll show you the three _non-hijacked_ Comcast DNS servers that are the shortest distance away. Perhaps you don't have Comcast (lucky you!), but hopefully this command can serve as an example of using netselect to find the fastest server from a list. Note that, although this example doesn't show it, netselect will actually perform the uniq and DNS resolution for you. Requires: netselect, curl, sort, uniq, grep Show Sample Output
This is sample output - yours may be different.
```
Running netselect to choose 3 out of 12 addresses.      
...........................................................................
   53 68.87.69.146
   62 68.87.76.178
  273 68.87.74.162
```
2

sudo netselect -v -s3 $(curl -s http://dns.comcast.net/dns-ip-addresses2.php | egrep -o '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' | sort | uniq)

hackerb9 · 2010-01-27 00:03:44 5
Using numsum to sum a column of numbers.

numsum is part of of the num-utils package, which is available in some Linux distros and can also be downloaded at http://suso.suso.org/xulu/Num-utils. It contains about 10 different programs for dealing with numbers from the command line. Obviously you can do a lot of things that the num-utils programs do in awk, sed, bash, perl scripts, but num-utils are there so that you don't have to remember the syntax for more complex operations and can just think: compute the sum, average, boundary numbers, etc. Show Sample Output
This is sample output - yours may be different.
```
15
```
5

numsum count.txt

deltaray · 2010-01-26 21:53:18 9
Give to anyone a command to immediatly find a particular part of a man.

Example : LC_ALL=C man less | less +/ppattern
This is sample output - yours may be different.
6

man <COMMAND> | less +'/pattern'

sputnick · 2010-01-26 20:50:00 3
Optimize PDF documents
This is sample output - yours may be different.
12

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

alamati · 2010-01-26 19:00:01 22
kde4 lock screen command

If you wish to launch the kde4 screen saver without the password prompt to exit, use this command: qdbus org.freedesktop.ScreenSaver /ScreenSaver org.freedesktop.ScreenSaver.SetActive True Also can be done with: /usr/lib/kde4/libexec/kscreenlocker --forcelock
This is sample output - yours may be different.
3

qdbus org.freedesktop.ScreenSaver /ScreenSaver Lock

starchox · 2010-01-26 17:50:10 5
Recursively grep for string and format output for vi(m)

This is a big time saver for me. I often grep source code and need to edit the findings. A single highlight of the mouse and middle mouse click (in gnome terminal) and I'm editing the exact line I just found. The color highlighting helps interpret the data.
This is sample output - yours may be different.
2

mgc() { grep --exclude=cscope* --color=always -rni $1 . |perl -pi -e 's/:/ +/' |perl -pi -e 's/^(.+)$/vi $1/g' |perl -pi -e 's/:/ /'; }

stinkerweed999 · 2010-01-26 17:00:01 4
Recursively grep thorugh directory for string in file.

Print line numbers also, so you don't have to search through the files once its open for the string you already grepped for.
This is sample output - yours may be different.
2

grep -rni string dir

stinkerweed999 · 2010-01-26 16:34:06 3
Show File System Hierarchy

Curious about differences between /bin, /usr/bin, and /usr/local/bin? What should be in the /sbin dir? Try this command to find out. Tested against Red Hat & OS X
This is sample output - yours may be different.
95

man hier

haivu · 2010-01-26 16:31:05 30
Recursively grep thorugh directory for string in file.

-R, -r, --recursive Read all files under each directory, recursively; this is equivalent to the -d recurse option.
This is sample output - yours may be different.
8

grep -r -i "phrase" directory/

TheFox · 2010-01-26 16:27:00 8
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convert a,b,c to ('a','b','c') for use in SQL in-clauses

Check if you work on a virtual/physical machine in Linux

Command used to know if we are working on a virtual or physical machine. This command will use the dmidecode utility to retrieve hardware information of your computer via the BIOS. Run this command as root or with sudo.

Kill XMMS for a cron job

Open a file at the specified line

You may also use +line:column syntax.

Generate random valid mac addresses

First set the variable $hexchars: $hexchars="0123456789ABCDEF" Change the number in the first for loop if you need less then 1200 mac addresses

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"

Alias TAIL for automatic smart output

Run the alias command, then issue $ps aux | tail and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand. $ ${LINES:-`tput lines 2>/dev/null||echo -n 12`} Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the default of 80. The default for TAIL is to output the last 10 lines, this alias changes the default to output the last x lines instead, where x is the number of lines currently displayed on your terminal - 7. The -7 is there so that the top line displayed is the command you ran that used TAIL, ie the prompt. Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux/bash-power-prompt.html ) 275MB/748MB [7995:7993 - 0:186] 06:26:49 Thu Apr 08 [askapache@n1-backbone5:/dev/pts/0 +1] ~ $ In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device.

View the latest astronomy picture of the day from NASA.

Substitute feh for the image viewer of your choice. display (part of imagemagick) seems to be a popular choice.

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" }

Detach a process from the current shell

Continue to execute the command in background even though quitting the shell.

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