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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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Easy way to scroll up und down to change to one of n last visited directories.

This alias is meant to append n (here is n=10) most recently used cd commands to the bottom of history file. This way you can easily change to one of previous visited directories simply by hitting 1-10 times arrow up key. Hint: You can make more aliases implying the same rule for any set of frequently used long and complex commands like: mkisof, rdesktop, gpg...

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"

Create arbitrary big file full of zeroes but done in a second

If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes. The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast). Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc... Command tested under Linux.

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"

make a log of a terminal session

Creates a log of a session in a file called typescript. Or specify the file with: $script filename Exit the session with control-d.

NICs, IPs, and Mac

Needed to get the Mac of various devices on a solaris box, but didn't have root. This command used awk to display the Network device, the IP, and the MAC a line at a time.

Email someone if a web page has been updated.

A cronjob command line to email someone when a webpages homepage is updated.

function to edit your history file

eh stands for Edit History . Frequently, I'll mistype a command, and then step back through my history and correct the command. As a result, both the correct and incorrect commands are in my history file. I wanted a simple way to remove the incorrect command so I don't run it by mistake. . When running this function, first the ~/bash_history file is updated, then you edit the file in vi, and then the saved history file is loaded back into memory for current usage. . while in vi, remember that `Shift-G` sends you to the bottom of the file, and `dd` removes a line. . this command is different than bash built-in `fc` because it does not run the command after editing.

Copy a file and force owner/group/mode

This is useful when you want to copy a file and also force a user, a group and a mode for that file. Note: if you want to move that file instead of copying it, you can use $install -o user -g group -m 755 /path/to/file /path/to/dir/ && rm -f /path/to/file which will remove the file only if the install command went fine.

Find files modified since a specific date

This command uses -newerXY to show you the files that are modified since a specific date. I recommend looking for "-newerXY" on the manpage to get the specifics.

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