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Assign top-level JSON entries to shell variables

A recursive version might be useful too. /dev/tty is used to show which shell variables just got defined. Show Sample Output
This is sample output - yours may be different.
```
a="42";
b="s t r i n g";
```
2

json='{"a":42, "b":"s t r i n g", "c": []}' ; eval $(echo $json | jq -r 'to_entries | .[] | select(.value | scalars) | .key + "=\"" + (.value | tostring) + "\";"' | tee /dev/tty)

penthief · 2023-09-26 03:11:38 683
MacOS: Make the terminal app always quit when

When you use the "exit" command in a Linux terminal window, it not only closes the terminal window itself but also the terminal emulator app, such as GNOME Terminal or Konsole, that it belongs to. If you use the "exit" command on macOS, however, Terminal.app still shows a dot below its Dock icon and is still running in the background. This alias, when entered into ~/.zshrc, overrides this behavior.
This is sample output - yours may be different.
-3

alias exit="killall Terminal"

realkstrawn93 · 2023-09-18 04:41:06 114
Get the beats per minute from an audio track

Requires bpm-tools https://www.pogo.org.uk/~mark/bpm-tools/ Show Sample Output
This is sample output - yours may be different.
```
119.900
```
1

ffmpeg -loglevel quiet -i "$AUDIO_FILE" -f f32le -ac 1 -ar 44100 - | bpm

malathion · 2023-09-16 18:55:16 74
Download Video & extract only a specific Time of it

Because this does not download more of the video than necessary, it is faster (especially with long videos).
This is sample output - yours may be different.
4

yt-dlp --external-downloader ffmpeg --external-downloader-args "-ss 00:05:00 -t 00:01:00" "https://www.youtube.com/watch?v=Y6DGABIcB3w"

malathion · 2023-09-16 18:04:12 71
Show temp of all disk

Show temp of all disk with the drivetemp module activate Show Sample Output
This is sample output - yours may be different.
```
WDC WD5000AAKX-0(38°C)
ST500DM002-1BD14(34°C)
WDC WD5000AAKX-0(35°C)
WDC WD80EFZX-68U(37°C)
WDC WD40EFPX-68C(32°C)
WDC WD40EMAZ-51T(31°C)
ST3160811AS     (39°C)
WDC WD40EZRZ-00W(35°C)
SAMSUNG HD501LJ (33°C)
SAMSUNG HD501LJ (35°C)
SAMSUNG HD501LJ (35°C)
SAMSUNG HD501LJ (36°C)
ST3500620AS     (34°C)
ST500DM002-1BD14(35°C)
WDC WD5000AAKS-6(38°C)
```
0

grep -l "drivetemp" /sys/class/hwmon/hwmon*/name | while read f; do printf "%s(%-.2s°C)\n" "`<${f%/*}/device/model`" "`<${f%/*}/temp1_input`"; done

kokoparkletal · 2023-09-10 18:24:29 75

Linux clear restrictions of a user's password

Command that clears the expiration restrictions of a user's password Show Sample Output

chage -E -1 -m 0 -M -1 -W -1 user01

net0bsd · 2023-08-21 06:37:40 178

Monitor changed files into a log file, with day rotation, using fswatch (MacOS)

This command monitors changes in the current folder structure (subfolders included) and files, and log it into a hidden file in the same folder, called `.file_changes_YYMMDD.log`. Modify the `--exclude` parameters to define what should be skipped. Show Sample Output

fswatch --exclude=.git/* --exclude=.settings --event-flags --event-flag-separator=\; -t -f '%Y-%m-%d %H:%M:%S' . >> ./.file_changes_$(date +"%Y-%m-%d" | sed s/-//g).log

paulera · 2023-08-17 23:06:30 194

Compute newest kernel version from Makefile on Torvalds' git repository

The platform-agnostic version of https://www.commandlinefu.com/commands/view/25276/compute-newest-kernel-version-from-makefile-on-torvalds-git-repository because macOS doesn't have wget installed
This is sample output - yours may be different.
1

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

realkstrawn93 · 2023-08-10 22:25:55 223
Sudoers: bypass all password prompts

If you as the sole user of a computer at home only don’t like needing to repeatedly type a password each time you run a command, using ‘NOPASSWD’ in sudoers for your specific username is for you.
This is sample output - yours may be different.
1

echo "$USER ALL=(ALL:ALL) NOPASSWD: ALL" | sudo tee -a /etc/sudoers

realkstrawn93 · 2023-08-10 22:19:18 157
Prepend section dates to individual entries in a summary log file

Searches for dates on lines by themselves. Uses that date to prepend all rows that contain SEARCHSTRING with the date, until it reaches another line with a date by itself. This fixed an issue with a specific log export where there would be a date, followed by all of the entries for that date.
This is sample output - yours may be different.
4

gawk 'match($0, /^\s*([0-9]{2}\/[0-9]{2}\/[0-9]{4})\s*/, m) {prev_date=m[1]} /SEARCHSTRING/ {print prev_date, ",", $1 $2, ",", $3, "," $5}' inputfile.txt

jtopian · 2023-07-11 23:20:38 454
Print macOS current power delivery max wattage

Print the max wattage of the current power draw source for a Mac. Note that the current amount of watts drawn may be lower, particularly if a high-wattage adapter is plugged into a Mac that has a full battery. Show Sample Output
This is sample output - yours may be different.
```
      Wattage (W): 140
```
1

system_profiler SPPowerDataType | grep Wattage

lgarron · 2023-07-06 17:58:00 198
Create a visually twisted effect by alternating the direction of the "staples" effect vertically. The effect is achieved by moving odd-numbered lines from right to left and even-numbered lines from left to right.

The effect is achieved by moving odd-numbered lines from right to left and even-numbered lines from left to right. For odd-numbered lines (with an index j), the ((j + i) % 2 == 0) condition is satisfied. In this case, the line width is set to i, resulting in the line moving from left to right. For even-numbered lines, the ((j + i) % 2 == 0) condition is not satisfied. The line width is set to $(tput cols) - i, causing the line to move from right to left. This alternating direction of movement creates a twisted visual effect as the lines appear to move in opposite directions. The code runs in a continuous loop, repeatedly updating the lines with changing background colors. There is a slight pause of 0.05 seconds between each iteration to control the speed of the animation.
This is sample output - yours may be different.
1

while :; do for ((i=0;i<$(tput cols);i++));do clear;for ((j=0;j<$(tput lines);j++));do printf "\e[48;5;$((RANDOM%256))m%*s\e[0m\n" $(((j+i)%2?$(tput cols)-i:i)) "";done;sleep 0.05;done;done

wuseman1 · 2023-07-04 00:47:37 241
Fill the screen with randomly colored lines

This one-liner fills the screen with randomly colored lines.
This is sample output - yours may be different.
2

while :; do printf "\e[48;2;$((RANDOM % 256));$((RANDOM % 256));$((RANDOM % 256))m%*s\e[0m" $(tput cols) ""; sleep 0.1; done

wuseman1 · 2023-07-04 00:38:46 343
Scan LAN and get Windows host names
This is sample output - yours may be different.
1

nmap -sn --system-dns 192.168.0.1-253

swarzynski · 2023-06-23 10:50:25 172
Check if a domain is available for purchase

A quick alias to check if a domain is already registered or if it's available for purchase. Show Sample Output
This is sample output - yours may be different.
```
$ canibuy commandlinefu.com
taken
$ canibuy commandlinekungfu.com
available
```
6

function canibuy { whois "$1" 2>/dev/null | grep -q 'Registrant' && echo "taken" || echo "available" }

tyzbit · 2023-06-21 15:01:25 170
This command provides more color variety for the rainbow-like appearance by generating random color codes from 16 to 231 for adb logcat.
This is sample output - yours may be different.
2

adb logcat|awk '{ i srand();for (i = 1; i <= NF; i++) { color = int(rand() * 216) + 16; printf "\033[38;5;%dm%s\033[0m ", color, $i;} printf "\n"; }'

wuseman1 · 2023-05-30 16:48:17 319
Disassemble all ACPI tables on your system

The fact that Linux exposes the ACPI tables to the user via sysfs makes them a gold mine of valuable hardware information for low-level developers. Looping through each of them and disassembling them all makes them even more valuable.
This is sample output - yours may be different.
1

for i in /sys/firmware/acpi/tables/*; do sudo iasl -p $PWD/$(echo $i | cut -d\/ -f6) $i && sudo chown $USER $(echo $i | cut -d\/ -f6); done

realkstrawn93 · 2023-04-16 05:33:51 541
Polkit: Force KDE apps to always recognize your display

KDE apps expect certain variables to be set, and unfortunately pkexec doesn’t set them by default. So, by setting this alias, it becomes possible to run, e.g. “pkexec kate” or “pkexec dolphin” and it’ll actually run.
This is sample output - yours may be different.
2

alias pkexec=“pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY KDE_SESSION_VERSION=5 KDE_FULL_SESSION=true”

realkstrawn93 · 2023-04-13 05:37:36 303
Loops over files, runs a command, dumps output to a file

In this case I'm selecting all php files in a dir, then echoing the filename and piping it to ~/temp/errors.txt. Then I'm running my alias for PHPCS (WordPress flags in my alias), then piping the PHPCS output to grep and looking for GET. Then I'm piping that output to the same file as above. This gets a list of files and under each file the GET security errors for that file. Extrapolate this to run any command on any list of files and pipe the output to a file. Remove the >> ~/temp/errors.txt to get output to the screen rather than to a file. Show Sample Output
This is sample output - yours may be different.
```
header.php
index.php
page.php
search.php
  19 | ERROR   | [ ] Detected usage of a possibly undefined superglobal array index: $_GET['s']. Use isset() or empty() to check the index exists before using it
  99 | ERROR   | [x] Short PHP opening tag used with echo; expected "<?php echo $_GET ..." but found "<?= $_GET ..."
  99 | ERROR   | [ ] All output should be run through an escaping function (see the Security sections in the WordPress Developer Handbooks), found '$_GET['s']'.
```
0

for f in *php; do echo $f >> ~/temp/errors.txt; phpcsw $f | grep GET >> ~/temp/errors.txt; done

topher1kenobe · 2023-04-12 14:17:14 357
Download Video & extract only a specific Time of it
This is sample output - yours may be different.
1

fmpeg $(yt-dlp -g 'https://de.pornhub.com/view_video.php?viewkey=ph637366806d6eb' | sed 's/^/-ss 00:05 -i /') -t 01:00 -c copy out.mp4

dbiesecke · 2023-04-01 17:39:01 326
urldecode with AWK

Fast and simple awk urldecoder! Note: Parameter -n is specific to GNU awk Show Sample Output
This is sample output - yours may be different.
```
echo -e  "asdf%2Fxx%2Cx\n%2F%2Cxx"  | awk -niord '{printf RT?$0chr("0x"substr(RT,2)):$0}' RS=%..
asdf/xx,x
/,xx
```
1

awk -niord '{printf RT?$0chr("0x"substr(RT,2)):$0}' RS=%..

emphazer · 2023-03-30 15:05:58 312
Create a square thumbnail or favicon using ImageMagick

Resize `file.png` to a 32x32 px image. Use a value other than 32 to create other icon sizes (e.g. 16x16 or 32x32). Combine two favicon sizes using: `convert icon-16px.png icon-32px.png favicon.ico` For a social media preview image, use `2:1#` for the extent and `1200` for the scale.
This is sample output - yours may be different.
8

convert file.png -background transparent -gravity Center -extent 1:1# -scale 32 file-32px.png

lgarron · 2023-03-08 04:11:12 601
List all files in a folder in a git repository by last commit date

This lists all the files in a folder, then finds the commit date for them one by one, then sorts them from newest to oldest
This is sample output - yours may be different.
4

git ls-tree --name-only HEAD foldername/ | while read filename; do echo "$(git log -1 --format="%ci " -- $filename) $filename"; done | sort -r

fivestones · 2023-03-01 17:02:51 264
A Console-based Audio Visualizer for ALSA

# Installing apt search cava sudo apt install cava # modify the default config to change the colors by their hex color code cava -p mkdir ~/.cava nano ~/.cava/config cava # run with changes!
This is sample output - yours may be different.
-2

cava

ioshield · 2023-02-28 19:53:42 355
Speak & Spell-esque glitch sounds

The Speak & Spell's sound chip uses a compressed audio format called "linear predictive coding". This command will read random bytes and attempt to decompress them as if it were audio data compressed in this format, then play it. This results in a unique sound which is similar to a glitching Speak & Spell.
This is sample output - yours may be different.
4

play -tlpc /dev/urandom

Sparkette · 2023-02-16 22:28:16 541
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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"

check open ports without netstat or lsof

Check a nfs mountpoint and force a remount if it does not reply after a given timeout.

Based on the execute with timeout command in this site. A more complex script: #!/bin/sh # This script will check the avaliability of a list of NFS mount point, # forcing a remount of those that do not respond in 5 seconds. # # It basically does this: # NFSPATH=/mountpoint TIMEOUT=5; perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $NFSPATH" || (umount -fl $NFSPATH; mount $NFSPATH) # TIMEOUT=5 SCRIPT_NAME=$(basename $0) for i in $@; do echo "Checking $i..." if ! perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $i" > /dev/null 2>&1; then echo "$SCRIPT_NAME: $i is failing with retcode $?."1>&2 echo "$SCRIPT_NAME: Submmiting umount -fl $i" 1>&2 umount -fl $i; echo "$SCRIPT_NAME: Submmiting mount $i" 1>&2 mount $i; fi done

Print just line 4 from a textfile

this method should be the fastest

list block devices

Shows all block devices in a tree with descruptions of what they are.

extract element of xml

Prints the value of a XML node rather than the entire node.

Rename files in batch

Remove Backup Files

Remove all text backup files.

Check which files are opened by Firefox then sort by largest size.

Just refining last proposal for this check, showing awk power to make more complex math (instead /1024/1024, 2^20). We don't need declare variable before run lsof, because $(command) returns his output. Also, awk can perform filtering by regexp instead to call grep. I changed the 0.0000xxxx messy output, with a more readable form purging all fractional numbers and files less than 1 MB.

external projector for presentations

i spent way too many hours trying to fiddle with /etc/X11/xorg.conf trying to hook up various external projectors. too bad i didn't know this would solve all my problems.

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