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Show current network interface in use
This is sample output - yours may be different.
1

ip addr | awk '/state UP/ {print $2}' | sed 's/.$//'

wuziduzi · 2021-05-17 16:05:35 60
scan multiple log subdirectories for the latest log files and tail them
This is sample output - yours may be different.
0

ls /var/log/* -ld | tr -s " " | cut -d" " -f9 | xargs -i{} sh -c 'echo "\n---{}---\n"; tail -n50 {}/`ls -tr {} | tail -n1`'

jgleeson · 2021-05-11 12:31:22 62
Finding the fingerprint of a given certificate
This is sample output - yours may be different.
1

openssl x509 -in cert.pem -fingerprint -noout

ohe · 2021-05-03 15:20:27 49
Fork bomb (don't actually execute)

“$0” is a variable returning the name of the script that you call it in — so running “./$0&” twice amounts to the script running itself in a separate process twice. Show Sample Output
This is sample output - yours may be different.
```
#!/bin/bash
./$0&
./$0&
```
-1

echo -e “\x23\x21/bin/bash\n\.\/\$\0\&\n\.\/\$\0\&” > bomb.sh && ./bomb.sh

realkstrawn93 · 2021-04-30 19:33:40 43
Compute newest kernel version from Makefile on Torvalds' git repository

Get newest kernel version by parsing the most bleeding-edge Makefile possible. Useful for doing things like writing live ebuilds and/or self-updating PKGBUILDs for testing purposes. Breakdown: * wget -qO - https://raw.githubusercontent.com/torvalds/linux/master/Makefile — retrieve Makefile and pipe to stdout * head -n5 — only the first 5 lines are relevant, that's where all the version variables are grep -E '\ \=\ [0-9]{1,}' — version variables always have an equals sign followed by a number * cut -d' ' -f3 — extract the individual numbers from the version variables * tr '\n' '.' — replace newlines with periods * sed -e "s/\.$// — remove trailing period Show Sample Output
This is sample output - yours may be different.
```
5.12.0
```
0

wget -qO - https://raw.githubusercontent.com/torvalds/linux/master/Makefile | head -n5 | grep -E '\ \=\ [0-9]{1,}' | cut -d' ' -f3 | tr '\n' '.' | sed -e "s/\.$//"

realkstrawn93 · 2021-04-27 17:12:05 84
Run entire shell script as root

Placing sudo in the shebang line of a shell script runs the entire thing as root. Useful for scripts designed to, e.g. automate system upgrades or package manager wrappers — makes prepending everything with sudo no longer necessary
This is sample output - yours may be different.
16

#!/usr/bin/sudo /bin/bash

realkstrawn93 · 2021-04-27 05:04:30 54
Quickly ping range of IP adresses and return only those that are online
This is sample output - yours may be different.
1

nmap -sP 192.168.0.0/24

snaguber · 2021-04-25 19:48:43 38
Quickly ping range of IP adresses and return only those that are online

Tested in Debian, ymmv. - c 1 : send only one ping;; -W 1: wait for one second and then exit ping, assuming target IP is not available; change as needed (-W 0.5 for half a second, smaller or greater value depending on network speed/latency)
This is sample output - yours may be different.
2

{ for i in {1..254}; do ping -c 1 -W 1 192.168.1.$i & done } | grep "64 bytes"

test666v2 · 2021-04-25 17:52:30 72
Quick and dirty hardware summary

Quick and dirty hardware summary where lshw is not available. Requires util-linux, procps, pciutils, usbutils and net-tools, which should be preinstalled on most systems.
This is sample output - yours may be different.
3

alias gethw='(printf "\nCPU\n\n"; lscpu; printf "\nMEMORY\n\n"; free -h; printf "\nDISKS\n\n"; lsblk; printf "\nPCI\n\n"; lspci; printf "\nUSB\n\n"; lsusb; printf "\nNETWORK\n\n"; ifconfig) | less'

lordtoran · 2021-04-03 00:41:12 177
Percental CPU scaled load average

This “sysload” alias converts the load average to percentages and divides them by the number of CPUs/cores. It may provide a more intuitive guesstimate of how much work the server is doing. Show Sample Output
This is sample output - yours may be different.
```
$ sysload

System load (1m/5m/15m): 31,5% 30,0% 29,8%
```
0

alias sysload='printf "System load (1m/5m/15m): "; for l in 1 2 3 ; do printf "%.1f%s" "$(( $(cat /proc/loadavg | cut -f $l -d " ") * 100 / $(nproc) ))" "% "; done; printf "\n"'

lordtoran · 2021-03-27 17:10:53 49
Command to logout all the users in one command
This is sample output - yours may be different.
9

sudo who | awk '!/root/{ cmd="/sbin/pkill -KILL -u " $1; system(cmd)}'

tg0000 · 2021-02-03 13:35:52 187
rename anime fansubs

renames Anime Episodes to files, that can be parsed by sonarr & co Show Sample Output
This is sample output - yours may be different.
```
rename([subs4u]_Mushishi_S2_22_(hi10p,720p,ger.sub)[47B73AEB].mkv, Mushishi_S2_22.mkv)
```
4

rename -n 's/[_ ]?[\[$]([A-Z0-9-+,\.]+)[\]$][_ ]?//ig' '[subs4u]_Mushishi_S2_22_(hi10p,720p,ger.sub)[47B73AEB].mkv'

dbiesecke · 2021-02-02 18:03:03 86
Save a copy of all debian packages in the form in which they are installed and configured on your system

A copy of all installed debian packages on your system will be put back together, with all changes in configuration files you made and placed in the current directory. Make sure you have enough disk space (say 2-3 GB). Break any time with Ctrl+C. Show Sample Output
This is sample output - yours may be different.
```
$ ls -1
accountsservice_0.6.45-1ubuntu1.3_amd64.deb
acl_2.2.52-3build1_amd64.deb
acpid_2.0.28-1ubuntu1_amd64.deb
acpi-support_0.142_amd64.deb
...
^C
(Ctrl+C)
```
5

for a in $(sudo dpkg --get-selections|cut -f1); do dpkg-repack $a|awk '{if (system("sleep .5 && exit 2") != 2) exit; print}';done

knoppix5 · 2021-01-17 17:07:02 85
Code to check if a module is used in python code
This is sample output - yours may be different.
-1

find . -name "*.ipynb" -exec grep -l "symspellpy" {} \;

shantanuo · 2021-01-17 03:49:03 47
rename / move Uppercase filenames to lowercase filenames current directory

move filename/rename filenames with Uppercase to lowercase in current directory Show Sample Output
This is sample output - yours may be different.
```
 FileList=$(ls); for FName in $FileList; do LowerFName=$(echo "$FName" | tr '[:upper:]' '[:lower:]'); echo $FName" rename/move to $LowerFName"; mv $FName $LowerFName;  done
```
2

FileList=$(ls); for FName in $FileList; do LowerFName=$(echo "$FName" | tr '[:upper:]' '[:lower:]'); echo $FName" rename/move to $LowerFName"; mv $FName $LowerFName; done

aysadk · 2021-01-06 16:11:00 109
SHA256 signature sum check of file

get the SHA256 sum signatur for a file Show Sample Output
This is sample output - yours may be different.
```
SHA256(exampleFile-0.20.1-x86_64-linux-gnu.tar.gz)= 376194f06596ecfa40331167c39bc70c355f960280bd2a645fdbf18f66527397
```
1

openssl dgst -sha256 <FILENAME>

aysadk · 2020-12-20 21:17:27 54
From all PDF files in all subdirectories, extract two metadata fields (here: Creator and Producer) into a CSV table
This is sample output - yours may be different.
0

echo "File;Creator;Producer";find . -name '*.pdf' -print0 | while IFS= read -d $'\0' line;do echo -n "$line;";pdfinfo "$line"|perl -ne 'if(/^(Creator|Producer):\s*(.*)$/){print"$2";if ($1 eq "Producer"){exit}else{print";"}}';echo;done 2>/dev/null

langec · 2020-12-17 21:08:55 87
Cryptographically secure 32-bit RNG in strict ZSH

ZSH ships a couple random number generators via the $RANDOM environment variable and rand48() via zsh/mathfunc, but neither are cryptographically secure. This code produces a 32-bit random number suitable for cryptography. It's only dependency is /dev/urandom and it does not rely on any shell commands or 3rd party utilities. It assumes ZSH was compiled with 64-bit integer support. Show Sample Output
This is sample output - yours may be different.
```
1018359216
```
1

srandom() { zmodload zsh/system; local byte; local -i rnd=0; repeat 4; do sysread -s 1 byte || return; rnd=$(( rnd << 8 | #byte )); done < /dev/urandom; print -r -- $rnd; }

atoponce · 2020-12-17 13:39:17 67
Individually 7zip all files in current directory
This is sample output - yours may be different.
0

for i in *.*; do 7z a "$i".7z "$i"; done

Romero · 2020-12-07 10:02:42 48
Moving large number of files

if you want to move with command mv large list of files than you would get following error /bin/mv: Argument list too long alternavite with exec: find /source/directory -mindepth 1 -maxdepth 1 -name '*' -exec mv {} /target/directory \; Show Sample Output
This is sample output - yours may be different.
```
 
```
3

find /source/directory -mindepth 1 -maxdepth 1 -name '*' -print0 | xargs -0 mv -t /target/directory;

aysadk · 2020-11-17 12:30:45 119
Show contents of all git objects in a git repo

This script finds all git objects and `git cat-file`'s their content. This is really just a helper function to play around with the internals of git repositories. See https://git-scm.com/book/en/v2/Git-Internals-Git-Objects of more info. Show Sample Output
This is sample output - yours may be different.
```
$ mkdir test1; cd test1; git init
$ echo hello | git hash-object --stdin -w
ce013625030ba8dba906f756967f9e9ca394464a

$ cd ..; git clone test1 test2; cd test2

# now we run the command and notice
# the objects have been cloned
$ find .git/objects/ -type f \| sed 's/\.git\/objects\/\///' | sed 's/\///g' | xargs -n1 -I% echo echo "%" \$$git cat-file -p "%"$ \0 | xargs -n1 -0 sh -c
4b825dc642cb6eb9a060e54bf8d69288fbee4904
ce013625030ba8dba906f756967f9e9ca394464a hello
```
1

find .git/objects/ -type f \| sed 's/\.git\/objects\/\///' | sed 's/\///g' | xargs -n1 -I% echo echo "%" \$$git cat-file -p "%"$ \0 | xargs -n1 -0 sh -c

wires · 2020-11-15 09:24:58 99
Rename all subtitles files with the same name of mp4 files in same folder

Use this command if you want to rename all subtitles for them to have the same name as the mp4 files. NOTE: The order of "ls -1 *.mp4" must match the order of "ls -1 *.srt", run the command bellow to make sure the *.srt files will really match the movies after run this command: paste -d:
This is sample output - yours may be different.
9

paste -d: <(ls -1 *.mp4) <(ls -1 *.srt) | while read line; do movie="${line%%:*}"; subtitle="${line##*:}"; mv "${subtitle}" "${movie%.*}.srt"; done

ricardofunke · 2020-11-08 02:47:13 177
tree command limit depth for recusive directory list

sometimes I need list from path with max limit for recursive depth directory listing
This is sample output - yours may be different.
5

tree -L 2 -u -g -p -d

aysadk · 2020-11-04 10:45:39 241
mural graffiti

apt install toilet toilet-fonts # replace 'tput setaf 1' with 'tput setaf 9' to change color
This is sample output - yours may be different.
-3

tput setaf 1;tput rev;h=$(tput lines);w=$[$(tput cols)/6];c=$(seq -ws '_____|' $[$w+1]|tr -d "0-9");for a in $(seq $[$h/2]);do echo $c;echo ${c//|___/___|};done;tput cup 0;toilet -t -f bigmono12 "?LOVE";tput cup $h

knoppix5 · 2020-11-01 13:31:31 157

while dumping database if you see following error/warning than you have to repair broken tables/rows Show Sample Output

mysqlcheck --repair --all-databases -u root -p<PASSWORD>

aysadk · 2020-10-30 11:52:20 113

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What's this?

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check open ports without netstat or lsof

dump the whole database

Always tail/edit/grep the latest file in a directory of timestamped files

zsh only If you have this command in your history, you can always re-run it and have it reference the latest file. The glob matches all timestamped files and then the resulting array is sorted by modification time (m) and then the first element in the sorted array is chosen (the latest)

Perform a C-style loop in Bash.

Print 0 through 99, each on a separate line.

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"

Search for a string inside all files in the current directory

shorter typing with no need to use xargs.

Countdown Clock

The biggest advantage over atoponce's nifty original is not killing the scrollback. Written assuming bash, but shouldn't be terribly difficult to port to other shells. S should be multiple spaces, but I can't get commandlinefu to save/show them properly, any help?

make image semi-transparent

Create an SSH SOCKS proxy server on localhost:8000 that will re-start itself if something breaks the connection temporarily

This command will log you into somehost via SSH and then go into the background (-f). From there, you can point e.g. firefox at localhost:8000 as a SOCKS proxy. Autossh will use port 20000 and 20001 to send and receive test data on those ports to ensure the SSH tunnel is still running, and will try to re-start the tunnel if it goes down. Make sure you have ssh-agent running, or passwordless ssh keys distributed between the two hosts.

Remove everything except that file

Remove everything except that file with shell tricks inside a subshell to avoid changes in the environment. $ help shopt

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