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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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Display the number of connections to a MySQL Database

Count the number of active connections to a MySQL database. The MySQL command "show processlist" gives a list of all the active clients. However, by using the processlist table, in the information_schema database, we can sort and count the results within MySQL.

Realtime apache hits per second

Change the cut range for hits per 10 sec, minute and so on... Grep can be used to filter on url or source IP.

Show a config file without comments

convert UNIX timestamp to UTC timestamp

date -ud @1320198157

Add all unversioned files to svn

Find and display most recent files using find and perl

This pipeline will find, sort and display all files based on mtime. This could be done with find | xargs, but the find | xargs pipeline will not produce correct results if the results of find are greater than xargs command line buffer. If the xargs buffer fills, xargs processes the find results in more than one batch which is not compatible with sorting. Note the "-print0" on find and "-0" switch for perl. This is the equivalent of using xargs. Don't you love perl? Note that this pipeline can be easily modified to any data produced by perl's stat operator. eg, you could sort on size, hard links, creation time, etc. Look at stat and just change the '9' to what you want. Changing the '9' to a '7' for example will sort by file size. A '3' sorts by number of links.... Use head and tail at the end of the pipeline to get oldest files or most recent. Use awk or perl -wnla for further processing. Since there is a tab between the two fields, it is very easy to process.

Convert PDF to JPEG using Ghostscript

Converting your PDF file to JPEG images. You can set resolution by -r option (default: 72dpi).

Copy a MySQL Database to a new Server via SSH with one command

Dumps a MySQL database over a compressed SSH tunnel and uses it as input to mysql - i think that is the fastest and best way to migrate a DB to a new server!

Resize a Terminal Window

Replace 70 with the desired height. Replace 180 with the desired width. I put it in my bashrc, because by default my terminal is too small.

Find out how old a web page is

I used to use the Firefox "View page info" feature a lot to determine how stale the web page I was looking at was. Now that I use mostly Chrome I miss that feature, so here is a command line alternative using wget. The -S says to display the server response, the --spider says to not download any files/pages, just fetch the header. The output goes to stderr, so to grep it you use 2>&1 to combine the stderr stream with stdout, the pipe that to grep for Last-Modified. You can use curl instead if you have it installed, like this: $ curl --head -s http://osswin.sourceforge.net | grep Mod

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