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Recompress all files in current directory from gzip to bzip2

Works even if file name contains \n. Spawns one job per core.
This is sample output - yours may be different.
0

parallel -0 'gzip -dc {} | bzip2 > {.}.bz2' ::: *.gz

unixmonkey91589 · 2015-12-25 17:28:03 9
Define a bash function to interactively pick a subdirectory to cd into
This is sample output - yours may be different.
0

function cdb() { select dir in $(find -type d -name "$1" -not -path '*/\.*' -prune); do cd "${dir}" && break; done }

oldo · 2017-04-08 14:40:11 59
List all IP's connected to port 80
This is sample output - yours may be different.
0

netstat -tn 2>/dev/null | grep :80 | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -nr | head

kumarrav90 · 2017-05-28 10:57:14 15
find hard linked files (duplicate inodes) recursively

If you have two sets of files that may share hard-linked files, it can be useful to identify which ones are hard links to same underlying inode (file). This command shows you all of those, sorted by inode#. In my example the two directory trees to compare share a common parent, so I run the command in that parent and just use find . to start from the current directory. If yours are in different locations, you can pass both paths to find: find /directory1 /directory2 -type f -printf '%10i %p\n' | sort | uniq -w 11 -d -D | less Show Sample Output
This is sample output - yours may be different.
```
 190186228 ./10/alpha1/2612_fsm
 190186228 ./12/alpha1/base/19108/2612_fsm
 190203401 ./10/alpha1/pg_internal.init
 190203401 ./12/alpha1/base/19108/pg_internal.init
 190206322 ./10/alpha1/3079_fsm
 190206322 ./12/alpha1/base/19108/3079_fsm
```
0

find . -type f -printf '%10i %p\n' | sort | uniq -w 11 -d -D | less

dmmst19 · 2020-09-13 22:12:58 385
Quickly add a new user to all groups the default user is in

an alternative to this one with only 2 processes https://www.commandlinefu.com/commands/view/25844/quickly-add-a-new-user-to-all-groups-the-default-user-is-in
This is sample output - yours may be different.
0

awk -F: '/^.+user1/{print $1}' /etc/group | xargs -n1 sudo adduser user2

ichbins · 2022-03-18 11:32:47 394
Extend LVM and online resize filesystem

Default volume group in Ubuntu is ubuntu-vg and the logical volume is ubuntu-lv, so the provided command will resize the disk to utilize 100% of the available space. Show Sample Output
This is sample output - yours may be different.
```
  Size of logical volume ubuntu-vg/ubuntu-lv changed from <14.25 GiB (3647 extents) to <28.50 GiB (7295 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.
resize2fs 1.45.5 (07-Jan-2020)
Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 4
The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 7470080 (4k) blocks long.
```
0

lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv && resize2fs /dev/ubuntu-vg/ubuntu-lv

sxiii · 2022-08-26 13:02:10 866
Need an ascii art font for you readme text ?

need toilet package , same goes for figlet showfigfonts | less : give the list of font available for options Show Sample Output
This is sample output - yours may be different.
```
_____                _ __  __      
|  __ \              | |  \/  |     
| |__) |___  __ _  __| | \  / | ___ 
|  _  // _ \/ _` |/ _` | |\/| |/ _ \
| | \ \  __/ (_| | (_| | |  | |  __/
|_|  \_\___|\__,_|\__,_|_|  |_|\___|
```
0

toilet -f big ReadMe

eastwind · 2009-04-22 05:48:13 4
Poor man's ntpdate

Good when firewalled and only in need of a reasonable accurate time. Use a fast responding web server.
This is sample output - yours may be different.
0

date -s "$(echo -e "HEAD / HTTP/1.0\n" | nc www.example.com 80 | sed -ne 's/^Date: $.*$$/\1/p')"

tomhol · 2010-01-08 20:05:00 9
zsh variable behave like bash variable

for exemple : var="echo hello"; $var this will display "hello" with bash with zsh, by default, this will make an error : "command not found : echo hello" hwordsplit option permit zsh to act like bash on this point
This is sample output - yours may be different.
0

setopt shwordsplit

Gentux · 2010-03-08 20:52:55 4
command line fu roulette

Splitting on tags in awk is a handy way to parse html.
This is sample output - yours may be different.
0

curl -sL 'www.commandlinefu.com/commands/random' | awk -F'</?[^>]+>' '/"command"/{print $2}'

putnamhill · 2010-08-13 11:42:42 5
rsync a hierarchy but matching only one filename

Applying filter rules is what makes this a really useful command. It's usually a pain to figure out how to sync ONLY files matching a particular pattern, and often one reverts to goofy stuff like find .. -exec rsync .. The filter hides all folders from the transfer, so that only the matching folders that store the filename are left for the sync.
This is sample output - yours may be different.
0

rsync -avz --dry-run --include="only-include-this-filename" -f 'hide,! */' source/folder/ target/folder/

cybertoast · 2011-03-16 16:10:42 3

Nmap find open TCP/IP ports for a target that is blocking ping

Change the IP address from 127.0.0.1 to the target machines ip address. Even if the target has ICMP (ping) blocked, it will show you what ports are open on the target. Very handy for situations where you know the target is up and online but wont respond to pings. Show Sample Output

nmap -sT -PN -vv <target ip>

Richie086 · 2011-07-22 02:37:19 8

grep for ip4 addresses
This is sample output - yours may be different.
0

grep -E "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"

kaplan2539 · 2012-06-27 08:13:14 3
Fastest way to get public IP
This is sample output - yours may be different.
0

curl simplesniff.com/ip

dotancohen · 2012-10-28 10:41:48 4
to remove blank line
This is sample output - yours may be different.
0

grep . filename >filename1

mervin123 · 2013-03-01 10:55:18 4
Logout from ubuntu
This is sample output - yours may be different.
0

logout

permanaj · 2013-04-23 02:35:59 4
[Ubuntu] Create a Python virtualenv
This is sample output - yours may be different.
0

virtualenv --no-site-packages --distribute -p /usr/bin/python3.3 ~/.virtualenvs/pywork3

kristallizer · 2013-09-14 22:13:05 6
Format source code noninteractively (possibly en masse) using vim's formatting functionality

The equivalent of opening each file in vim and doing gg=G:wq . Bufdo makes it faster by obviating the need to start vim for each file separately.
This is sample output - yours may be different.
0

vim +"bufdo norm gg=G" +wa +qa FILES

pjump · 2013-12-06 22:15:24 6
Recursively convert all APE to FLAC

Converts all monkey audio files below currently directory to FLAC. For only current directory, use `for f in *.ape; do avconv -i "$f" "${f%.ape}.flac"; done` To remove APE files afterward, use `rm */*.ape`
This is sample output - yours may be different.
0

for f in */*.ape; do avconv -i "$f" "${f%.ape}.flac"; done

qdrizh · 2014-10-10 12:33:00 8
Check Rubocop offenses in your working branch

Assumes you are in the branch you want to run the check on. Sub 'develop' for whatever branch you commonly submit PRs to. Show Sample Output
This is sample output - yours may be different.
```
== spec/support/stripe_endpoint_helpers.rb ==
C:  6: 81: Line is too long. [82/80]
C:163:114: Space inside square brackets detected.
W:231: 25: Unused block argument - value. If it's necessary, use _ or _value as an argument name to indicate that it won't be used.

37 files inspected, 3 offenses detected
```
0

git rev-parse develop | xargs git diff --name-only | grep -E '^(app|lib|spec).*\.rb' | xargs rubocop -f simple

vinniefranco · 2015-01-21 08:12:18 8
Find text in contents with multiple filename

-name : base of filename -o : 'or' '*.c' : avoiding "paths must precede expression" error message -type f : only find file type --color: hightlight specific word with color -E : extended regexp Show Sample Output
This is sample output - yours may be different.
```
./test.c: int Data;
./test.c: int iData;
./test.h: float fnData();
```
0

find ./$(PATH) -name '*.h' -o -name '*.c' -type f | xargs grep --color -E '*Data*'

debpolaris · 2017-02-10 04:17:16 19
Remove files and show space freed

Give the space freed before delete files. Only delete files go to free space. Files with mora than 1 link, don't free space. Show Sample Output
This is sample output - yours may be different.
```
find . -maxdepth 1 -links 1  -exec du -shc {} + -exec rm -v {} +
4,0K	./file1
4,0K	./file5
4,0K	./file6
4,0K	./mvfiles.sh
4,0K	./file3
4,0K	./file2
24K	total
?./file1? borrado
?./file5? borrado
?./file6? borrado
?./mvfiles.sh? borrado
?./file3? borrado
?./file2? borrado
```
0

find . -link 1 -exec du {} -shc + -exec rm -v {} +

Wallebot · 2017-02-27 17:52:17 18
Get the total length of all video / audio in the current dir (and below) in H:m:s

Uses soxi instead of mplayer
This is sample output - yours may be different.
0

soxi -D * | awk '{SUM += $1} END { printf "%d:%d:%d\n",SUM/3600,SUM%3600/60,SUM%60}'

hufman · 2017-04-08 17:37:03 15
Use was ec2 describe instances to retrieve IAM roles for specific ec2 tag to css list

This allows you to get all instance profiles (roles) for a given set of tags. Lists it in CSV Show Sample Output
This is sample output - yours may be different.
```
"arn:aws:iam::111114168247:instance-profile/Yourole-Instance-Profile,i-01ab14691695a0fa1"
```
0

aws ec2 describe-instances --region us-east-1 --filters "Name=tag:YourTag,Values=YourValue" | jq '.["Reservations"]|.[]|.Instances|.[]|.IamInstanceProfile.Arn + "," +.InstanceId'

symgryph · 2019-04-15 16:33:41 34
Sort movies by length, longest first

Similar but using mediainfo instead of totem-something
This is sample output - yours may be different.
0

for i in *.avi; do echo -n "$i:";mediainfo $i|head | grep PlayTime | cut -d: -f2 ; done | sort -t: -k2 -r

yooreck · 2009-11-09 12:42:20 3
‹ First < 405 406 407 408 409 > Last ›

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history autocompletion with arrow keys

This will enable the possibility to navigate in the history of the command you type with the arrow keys, example "na" and the arrow will give all command starting by na in the history.You can add these lines to your .bashrc (without &&) to use that in your default terminal.

wget multiple files (or mirror) from NTLM-protected Sharepoint

If you have to deal with MS Sharepoint which is (rarely, let's hope) used in e.g. certain corporate environments). This uses Cntlm. For single files, just use cURL -- its NTLM authentication works quite well. # /etc/cntlm.conf: # Username account # Domain domain # Password ############ # Proxy 10.20.30.40 (IP of the sharepoint site) # NoProxy * # Listen 3128

Find out which process uses an old lib and needs a restart after a system update

Shows the full output of lsof.

Move cursor to end of line

Smart `cd`.. cd to the file directory if you try to cd to a file

This little function will smarten 'cd'. If you try to cd into a file (which I guess we all have done), it cd's into the directory of that file instead. I had to use nesten if's, to get cd to still work with 'cd' (to get to $HOME), 'cd -' (to get to last directory), and 'cd foo\ bar'.

Get IPv4 of eth0 for use with scripts

I've been using it in a script to build from scratch proxy servers.

Escape potential tarbombs

This Anti-TarBomb function makes it easy to unpack a .tar.gz without worrying about the possibility that it will "explode" in your current directory. I've usually always created a temporary folder in which I extracted the tarball first, but I got tired of having to reorganize the files afterwards. Just add this function to your .zshrc / .bashrc and use it like this; $ atb arch1.tar.gz and it will create a folder for the extracted files, if they aren't already in a single folder. This only works for .tar.gz, but it's very easy to edit the function to suit your needs, if you want to extract .tgz, .tar.bz2 or just .tar. More info about tarbombs at http://www.linfo.org/tarbomb.html Tested in zsh and bash. UPDATE: This function works for .tar.gz, .tar.bz2, .tgz, .tbz and .tar in zsh (not working in bash): $ atb() { l=$(tar tf $1); if [ $(echo "$l" | wc -l) -eq $(echo "$l" | grep $(echo "$l" | head -n1) | wc -l) ]; then tar xf $1; else mkdir ${1%.t(ar.gz||ar.bz2||gz||bz||ar)} && tar xf $1 -C ${1%.t(ar.gz||ar.bz2||gz||bz||ar)}; fi ;} UPDATE2: From the comments; bepaald came with a variant that works for .tar.gz, .tar.bz2, .tgz, .tbz and .tar in bash: $ atb() {shopt -s extglob ; l=$(tar tf $1); if [ $(echo "$l" | wc -l) -eq $(echo "$l" | grep $(echo "$l" | head -n1) | wc -l) ]; then tar xf $1; else mkdir ${1%.t@(ar.gz|ar.bz2|gz|bz|ar)} && tar xf $1 -C ${1%.t@(ar.gz|ar.bz2|gz|bz|ar)}; fi ; shopt -u extglob}

An easter egg built into python to give you the Zen of Python

Checks throughput between two nodes

This will show the throughput between two nodes. Thanks to szboardstretcher, who posted it here: http://www.linuxquestions.org/questions/linux-networking-3/quick-and-easy-way-to-measure-throughput-between-two-nodes-868998/

Remove comments from files

Use sed to remove comments from a file. In this example the comments begin with #. The command '/^#/d' remove line starting with #. The command 's/#.*$//' remove comments at end of lines.

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