4chars

acpi
Shows battery status or thermal information

More information: https://sourceforge.net/projects/acpiclient/files/acpiclient/.

- Show battery information: acpi

- Show thermal information: acpi -t

- Show cooling device information: acpi -c

- Show thermal information in Fahrenheit: acpi -tf

- Show all information: acpi -V

- Extract information from /proc instead of /sys: acpi -p

beep
A utility to beep the PC speaker

More information: https://github.com/spkr-beep/beep.

- Play a beep: beep

- Play a beep that repeats: beep -r

- Play a beep at a specified frequency (Hz) and duration (milliseconds): beep -f -l

- Play each new frequency and duration as a distinct beep: beep -f -l  -n -f  -l

- Play the C major scale: beep -f 262 -n -f 294 -n -f 330 -n -f 349 -n -f 392 -n -f 440 -n -f 494 -n -f 523

bmon
Monitor bandwidth and capture network related statistics

More information: https://github.com/tgraf/bmon.

- Display the list of all the interfaces: bmon -a

- Display data transfer rates in bits per second: bmon -b

- Set policy to define which network interface(s) is/are displayed: bmon -p

- Set interval (in seconds) in which rate per counter is calculated: bmon -R

calc
An interactive arbitrary-precision calculator on the terminal

More information: https://github.com/lcn2/calc.

- Start calc in interactive mode: calc

- Perform a calculation in non-interactive mode: calc -p ''

ceph
A unified storage system

More information: https://ceph.io.

- Check cluster health status: ceph status

- Check cluster usage stats: ceph df

- Get the statistics for the placement groups in a cluster: ceph pg dump --format

- Create a storage pool: ceph osd pool create

- Delete a storage pool: ceph osd pool delete

- Rename a storage pool: ceph osd pool rename

- Self-repair pool storage: ceph pg repair

cewl
URL spidering tool for making a cracking wordlist from web content

More information: https://digi.ninja/projects/cewl.php.

- Create a wordlist file from the given URL up to 2 links depth: cewl --depth --write  undefined

- Output an alphanumeric wordlist from the given URL with words of minimum 5 characters: cewl --with-numbers --min_word_length undefined

- Output a wordlist from the given URL in debug mode including email addresses: cewl --debug --email undefined

- Output a wordlist from the given URL using HTTP Basic or Digest authentication: cewl --auth_type --auth_user  --auth_pass  undefined

- Output a wordlist from the given URL through a proxy: cewl --proxy_host --proxy_port  undefined

chfn
Update finger info for a user

More information: https://manned.org/chfn.

- Update a user's "Name" field in the output of finger: chfn -f

- Update a user's "Office Room Number" field for the output of finger: chfn -o

- Update a user's "Office Phone Number" field for the output of finger: chfn -p

- Update a user's "Home Phone Number" field for the output of finger: chfn -h

chrt
Manipulate the real-time attributes of a process

More information: https://man7.org/linux/man-pages/man1/chrt.1.html.

- Display attributes of a process: chrt --pid

- Display attributes of all threads of a process: chrt --all-tasks --pid

- Display the min/max priority values that can be used with chrt: chrt --max

- Set the scheduling policy for a process: chrt --pid --

cmus
Command-line Music Player.Use arrow keys to navigate,  to select, and numbers 1-8 switch between different views

More information: https://cmus.github.io.

- Open cmus into the specified directory (this will become your new working directory): cmus

- Add file/directory to library: :add

- Pause/unpause current song: c

- Toggle shuffle mode on/off: s

- Quit cmus: q

cuyo
Tetris like game

More information: https://www.karimmi.de/cuyo/.

- Start a new game: cuyo

- Navigate the piece horizontally: OR Right arrow key

- Turn the piece:

- Hard drop the piece:

dget
Download Debian packages

More information: https://manpages.debian.org/dget.

- Download a binary package: dget

- Download and extract a package source from its .dsc file: dget

- Download a package source tarball from its .dsc file but don't extract it: dget -d

dkms
A framework that allows for dynamic building of kernel modules

More information: https://github.com/dell/dkms.

- List currently installed modules: dkms status

- Rebuild all modules for the currently running kernel: dkms autoinstall

- Install version 1.2.1 of the acpi_call module for the currently running kernel: dkms install -m -v

- Remove version 1.2.1 of the acpi_call module from all kernels: dkms remove -m -v  --all

dpkg
Debian package manager

More information: https://manpages.debian.org/buster/dpkg/dpkg.1.en.html.

- Install a package: dpkg -i

- Remove a package: dpkg -r

- List installed packages: dpkg -l

- List a package's contents: dpkg -L

- List contents of a local package file: dpkg -c

- Find out which package owns a file: dpkg -S

edit
An alias to a run-mailcap's action edit.Originally run-mailcap is used to process/edit mime-type/file

More information: https://www.computerhope.com/unix/uedit.htm.

- Edit action can be used to view any file on default mailcap explorer: edit

- With run-mailcap: run-mailcap --action=edit

eval
Execute arguments as a single command in the current shell and return its result

More information: https://manned.org/eval.

- Call echo with the "foo" argument: eval ""

- Set a variable in the current shell: eval ""

exif
Show and change EXIF information in JPEG files

More information: https://github.com/libexif/exif/.

- Show all recognized EXIF information in an image: exif

- Show a table listing known EXIF tags and whether each one exists in an image: exif --list-tags --no-fixup

- Extract the image thumbnail into the file thumbnail.jpg: exif --extract-thumbnail --output=

- Show the raw contents of the "Model" tag in the given image: exif --ifd= --tag= --machine-readable

- Change the value of the "Artist" tag to John Smith and save to new.jpg: exif --output= --ifd= --tag="" --set-value="" --no-fixup

ffuf
Subdomain and directory discovery tool

More information: https://github.com/ffuf/ffuf.

- Discover directories using a [w]ordlist on a target [u]rl with [c]olorized and [v]erbose ouput: ffuf -w -u  -c -v

- Fuzz host-[H]eaders with a host file on a traget website and [m]atch HTTP 200 [c]ode responses: ffuf -w -u  -H "" -mc

- Discover directories using a [w]ordlist on a target website with a max individual job time of 60 seconds and recursion discovery depth of 2 levels: ffuf -w -u  -maxtime-job  -recursion -recursion-depth

- Fuzz GET parameter on a target website and [f]ilter out message [s]ize response of 4242 bytes: ffuf -w -u  -fs

- Fuzz POST method with POST [d]ata of password on a target website and [f]ilter out HTTP response [c]ode 401: ffuf -w -X  -d "" -u  -fc

- Discover subdomains using a subdoomain list on a target website: ffuf -w -u  -H ""

file
Determine file type

More information: https://manned.org/file.

- Give a description of the type of the specified file. Works fine for files with no file extension: file

- Look inside a zipped file and determine the file type(s) inside: file -z

- Allow file to work with special or device files: file -s

- Don't stop at first file type match; keep going until the end of the file: file -k

- Determine the mime encoding type of a file: file -i

free
Display amount of free and used memory in the system

More information: https://manned.org/free.

- Display system memory: free

- Display memory in Bytes/KB/MB/GB: free -

- Display memory in human-readable units: free -h

- Refresh the output every 2 seconds: free -s

fsck
Check the integrity of a filesystem or repair it. The filesystem should be unmounted at the time the command is run

More information: https://manned.org/fsck.

- Check filesystem /dev/sdX, reporting any damaged blocks: fsck

- Check filesystem /dev/sdX, reporting any damaged blocks and interactively letting the user choose to repair each one: fsck -r

- Check filesystem /dev/sdX, reporting any damaged blocks and automatically repairing them: fsck -a

gcov
Code coverage analysis and profiling tool that discovers untested parts of a program.Also displays a copy of source code annotated with execution frequencies of code segments

More information: https://gcc.gnu.org/onlinedocs/gcc/Invoking-Gcov.html.

- Generate a coverage report named file.cpp.gcov: gcov

- Write individual execution counts for every basic block: gcov --all-blocks

- Write branch frequencies to the output file and print summary information to stdout as a percentage: gcov --branch-probabilities

- Write branch frequencies as the number of branches taken, rather than the percentage: gcov --branch-counts

- Do not create a gcov output file: gcov --no-output

- Write file level as well as function level summaries: gcov --function-summaries

halt
Halt the system

More information: https://www.man7.org/linux/man-pages/man8/halt.8.html.

- Halt the system: halt

- Power off the system (same as poweroff): halt --poweroff

- Reboot the system (same as reboot): halt --reboot

- Halt immediately without contacting the system manager: halt --force --force

- Write the wtmp shutdown entry without halting the system: halt --wtmp-only

ifup
Tool used to enable network interfaces

More information: https://manpages.debian.org/latest/ifupdown/ifup.8.html.

- Enable interface eth0: ifup

- Enable all the interfaces defined with "auto" in /etc/network/interfaces: ifup -a

imgp
Command-line image resizer and rotator for JPEGs and PNGs.

- Convert single images and/or whole directories containing valid image formats: imgp -x

- Scale an image by 75% and overwrite the source image to a target resolution: imgp -x -w

- Rotate an image clockwise by 90 degrees: imgp -o

inxi
Print a summary of system information and resources for debugging purposes.

- Print a summary of CPU, memory, hard drive and kernel information: inxi

- Print a full description of CPU, memory, disk, network and process information: inxi -Fz

- Print information about the distribution's repository: inxi -r

jobs
Display status of jobs in the current session.

- Show status of all jobs: jobs

- Show status of a particular job: jobs %

- Show status and process IDs of all jobs: jobs -l

- Show process IDs of all jobs: jobs -p

lftp
Sophisticated file transfer program

More information: https://lftp.yar.ru/lftp-man.html.

- Connect to an FTP server: lftp

- Download multiple files (glob expression): mget

- Upload multiple files (glob expression): mput

- Delete multiple files on the remote server: mrm

- Rename a file on the remote server: mv

- Download or update an entire directory: mirror

- Upload or update an entire directory: mirror -R

line
Read a single line of input

More information: https://manned.org/line.

- Read input: line

lshw
List detailed information about hardware configurations as root user

More information: https://manned.org/lshw.

- Launch the GUI: sudo lshw -X

- List all hardware in tabular format: sudo lshw -short

- List all disks and storage controllers in tabular format: sudo lshw -class disk -class storage -short

- Save all network interfaces to an HTML file: sudo lshw -class network -html >

maim
Screenshot utility

More information: https://github.com/naelstrof/maim.

- Capture a screenshot and save it to the given path: maim

- Capture a screenshot of the selected region: maim --select

- Capture a screenshot of the selected region and save it in the clipboard (requires xclip): maim --select | xclip -selection clipboard -target image/png

- Capture a screenshot of the current active window (requires xdotool): maim --window $(xdotool getactivewindow)

mkfs
Build a Linux filesystem on a hard disk partition.This command is deprecated in favor of filesystem specific mkfs. utils

More information: https://manned.org/mkfs.

- Build a Linux ext2 filesystem on a partition: mkfs

- Build a filesystem of a specified type: mkfs -t

- Build a filesystem of a specified type and check for bad blocks: mkfs -c -t

mocp
Music on Console (MOC) audio player

More information: https://manned.org/mocp.

- Launch the MOC terminal UI: mocp

- Launch the MOC terminal UI in a specific directory: mocp

- Start the MOC server in the background, without launching the MOC terminal UI: mocp --server

- Add a specific song to the play queue while MOC is in the background: mocp --enqueue

- Add songs recursively to the play queue while MOC is in the background: mocp --append

- Clear the play queue while MOC is in the background: mocp --clear

- Play or stop the currently queued song while MOC is in the background: mocp --

- Stop the MOC server while it's in the background: mocp --exit

mono
Runtime for the .NET Framework

More information: https://www.mono-project.com/docs/.

- Run a .NET assembly in debug mode: mono --debug

- Run a .NET assembly: mono

mons
A tool to quickly manage two displays

More information: https://github.com/Ventto/mons.

- Enable only the primary monitor: mons -o

- Enable only the secondary monitor: mons -s

- Duplicate the primary monitor onto the secondary monitor, using the resolution of the primary monitor: mons -d

- Mirror the primary monitor onto the secondary monitor, using the resolution of the secondary monitor: mons -m

mssh
GTK+ based SSH client for interacting with multiple SSH servers at once

More information: https://manned.org/mssh.

- Open a new window and connect to multiple SSH servers: mssh

- Open a new window and connect to a group of servers predefined in ~/.mssh_clusters: mssh --alias

ncat
Use the normal cat functionality over networks.

- Listen for input on the specified port and write it to the specified file: ncat -l >

- Accept multiple connections and keep ncat open after they have been closed: ncat -lk

- Write output of specified file to the specified host on the specified port: ncat  <

ncdu
Disk usage analyzer with an ncurses interface.

- Analyze the current working directory: ncdu

- Analyze a given directory: ncdu

- Save results to a file: ncdu -o

- Exclude files that match a pattern, argument can be given multiple times to add

More patterns: ncdu --exclude ''

nemo
File manager and graphical shell for Cinnamon

More information: https://github.com/linuxmint/nemo.

- Open a new window showing the user's home directory: nemo

- Open a new window showing the current directory: nemo.

- Close all open nemo windows: nemo --quit

nmon
A system administrator, tuner, and benchmark tool.

- Start nmon: nmon

- Save records to file ("-s 300 -c 288" by default): nmon -f

- Save records to file with a total of 240 measurements, by taking 30 seconds between each measurement: nmon -f -s -c

ntpq
Query the Network Time Protocol (NTP) daemon

More information: https://www.eecis.udel.edu/~mills/ntp/html/ntpq.html.

- Start ntpq in interactive mode: ntpq --interactive

- Print a list of NTP peers: ntpq --peers

- Print a list of NTP peers without resolving hostnames from IP addresses: ntpq --numeric --peers

- Use ntpq in debugging mode: ntpq --debug-level

- Print NTP system variables values: ntpq --command=RV undefined

opkg
A lightweight package manager used to install OpenWrt packages.

- Install a package: opkg install

- Remove a package: opkg remove

- Update the list of available packages: opkg update

- Upgrade all the installed packages: opkg upgrade

- Upgrade one or

More specific package(s): opkg upgrade

- Display information for a specific package: opkg info

- List all the available packages: opkg list

paru
An AUR helper and pacman wrapper

More information: https://github.com/Morganamilo/paru.

- Interactively search for and install a package: paru

- Synchronize and update all packages: paru

- Upgrade AUR packages: paru -Sua

- Get information about a package: paru -Si

- Download PKGBUILD and other package source files from the AUR or ABS: paru --getpkgbuild

- Display the PKGBUILD file of a package: paru --getpkgbuild --print

perf
Framework for Linux performance counter measurements.

- Display basic performance counter stats for a command: perf stat

- Display system-wide real-time performance counter profile: sudo perf top

- Run a command and record its profile into perf.data: sudo perf record

- Read perf.data (created by perf record) and display the profile: sudo perf report

phar
Create, update or extract PHP archives (PHAR).

- Add space-separated files or directories to a Phar file: phar add -f

- Display the contents of a Phar file: phar list -f

- Delete the specified file or directory from a Phar file: phar delete -f -e

- Display full usage information and available hashing/compression algorithms: phar help

- Compress or uncompress files and directories in a Phar file: phar compress -f -c

- Get information about a Phar file: phar info -f

- Sign a Phar file with a specific hash algorithm: phar sign -f -h

- Sign a Phar file with an OpenSSL private key: phar sign -f -h openssl -y

pwdx
Print working directory of a process.

- Print current working directory of a process: pwdx

qsub
Submits a script to the queue management system TORQUE.

- Submit a script with default settings (depends on TORQUE settings): qsub

- Submit a script with a specified wallclock runtime limit of 1 hour, 2 minutes and 3 seconds: qsub -l walltime=::

- Submit a script that is executed on 2 nodes using 4 cores per node: qsub -l nodes=:ppn=

- Submit a script to a specific queue. Note that different queues can have different maximum and minimum runtime limits: qsub -q

rofi
An application launcher and window switcher

More information: https://github.com/davatorium/rofi.

- Show the list of apps: rofi -show drun

- Show the list of all commands: rofi -show run

- Switch between windows: rofi -show window

- Pipe a list of items to stdin and print the selected item to stdout: printf "" | rofi -dmenu

slop
Get a selection of the screen

More information: https://github.com/naelstrof/slop.

- Wait for the user to make a selection and output its geometry to standard output: slop

- Double click, rather than click and drag, to draw a selection: slop -D

- Highlight the selection rather than outlining it: slop -l

- Specify the output format: slop -f

- Specify the selection rectangle's color: slop -c ,,,

snap
Tool for managing the "snap" self-contained software packages.Similar to what apt is for ".deb".

- Search for a package: snap find

- Install a package: snap install

- Update a package: snap refresh

- Update a package to another channel (track, risk, or branch): snap refresh --channel=

- Update all packages: snap refresh

- Display basic information about installed snap software: snap list

- Uninstall a package: snap remove

- Check for recent snap changes in the system: snap changes

srun
Create an interactive slurm job or connect to an existing job

More information: https://slurm.schedmd.com/srun.html.

- Submit a basic interactive job: srun --pty /bin/bash

- Submit an interactive job with different attributes: srun --ntasks-per-node= --mem-per-cpu= --pty /bin/bash

- Connect to a worker node with a job running: srun --jobid= --pty /bin/bash

sxiv
Simple X Image Viewer

More information: https://github.com/muennich/sxiv.

- Open an image: sxiv

- Open an image in fullscreen mode: sxiv -f

- Open a newline-separated list of images, reading filenames from standard input: echo | sxiv -i

- Open a space-separated list of images as a slideshow: sxiv -S

- Open a space-separated list of images in thumbnail mode: sxiv -t

tomb
Manage encrypted storage directories that can be safely transported and hidden in a filesystem

More information: https://www.dyne.org/software/tomb/.

- Create a new tomb with an initial size of 100 MB: tomb dig -s

- Create a new key file that can be used to lock a tomb; user will be prompted for a password for the key: tomb forge

- Forcefully create a new key, even if the tomb isn't allowing key forging (due to swap): tomb forge -f

- Initialize and lock an empty tomb using a key made with forge: tomb lock -k

- Mount a tomb (by default in /media) using its key, making it usable as a regular filesystem directory: tomb open -k

- Close a tomb (fails if the tomb is being used by a process): tomb close

- Forcefully close all open tombs, killing any applications using them: tomb slam all

- List all open tombs: tomb list

trap
Automatically execute commands after receiving signals by processes or the operating system.Can be used to perform cleanups for interruptions by the user or other actions

More information: https://manned.org/trap.

- List available signals to set traps for: trap -l

- List active traps for the current shell: trap -p

- Set a trap to execute commands when one or

More signals are detected: trap 'echo "Caught signal "'

- Remove active traps: trap -

tree
Show the contents of the current directory as a tree

More information: http://mama.indstate.edu/users/ice/tree/.

- Print files and directories up to 'num' levels of depth (where 1 means the current directory): tree -L

- Print directories only: tree -d

- Print hidden files too with colorization on: tree -a -C

- Print the tree without indentation lines, showing the full path instead (use -N to not escape non-printable characters): tree -i -f

- Print the size of each file and the cumulative size of each directory, in human-readable format: tree -s -h --du

- Print files within the tree hierarchy, using a wildcard (glob) pattern, and pruning out directories that don't contain matching files: tree -P '' --prune

- Print directories within the tree hierarchy, using the wildcard (glob) pattern, and pruning out directories that aren't ancestors of the wanted one: tree -P --matchdirs --prune

- Print the tree ignoring the given directories: tree -I ''

tuxi
A CLI tool that scrapes Google search results and SERPs that provides instant and concise answers

More information: https://github.com/Bugswriter/tuxi.

- Make a search using Google: tuxi

- Display the search results in [r]aw format (no pretty output, no colors): tuxi -r

- Display only search results (silences "Did you mean?", greetings and usage): tuxi -q

- Display help: tuxi -h

uuid
Generate and decode Universally Unique Identifiers (UUID).See also uuidgen

More information: https://manned.org/uuid.

- Generate a UUIDv1 (based on time and system's hardware address, if present): uuid

- Generate a UUIDv4 (based on random data): uuid -v

- Generate multiple UUIDv4 identifiers at once: uuid -v -n

- Generate a UUIDv4 and specify the output format: uuid -v -F

- Generate a UUIDv4 and write the output to a file: uuid -v -o

- Generate a UUIDv5 (based on the supplied object name) with a specified namespace prefix: uuid -v ns:

- Decode a given UUID: uuid -d

vipw
Edit the password file

More information: https://manned.org/vipw.

- Edit the password file: vipw

- Display the current version of vipw: vipw --version

vpnc
A VPN client for the Cisco 3000 VPN Concentrator.

- Connect with a defined configuration file: sudo vpnc

- Terminate the previously created connection: sudo vpnc-disconnect

vrms
Report non-free packages installed on Debian-based OSes

More information: https://debian.pages.debian.net/vrms/.

- List non-free and contrib packages (and their description): vrms

- Only output the package names: vrms --sparse

wall
Write a message on the terminals of users currently logged in.

- Send a message: echo "" | wall

- Send a message from a file: wall

- Send a message with timeout (default 300): wall -t

wine
Run Windows programs on Unix

More information: https://wiki.winehq.org/.

- Run ipconfig.exe program: wine

- Run cmd.exe in background: wine start

- Run Windows-like Package Manager: wine uninstaller

- Install MSI packages: wine msiexec /i

xbps
The X Binary Package System (or xbps) is the binary package system used by Void Linux

More information: https://github.com/void-linux/xbps.

- Install packages and synchronize them with the remote repository: xbps-install --synchronize

- Search for a package in the remote repository: xbps-query --repository -s

- Remove a package, leaving all of its dependencies installed: xbps-remove

- Remove a package and all of its dependencies recursively that are not required by other packages: xbps-remove --recursive

- Synchronize your repository databases and update your system and dependencies: xbps-install --synchronize -u

- Remove packages that were installed as dependencies and aren't currently needed: xbps-remove --remove-orphans

- Remove obsolete packages from the cache: xbps-remove --clean-cache

xman
Manual page viewer for X Window System.

- Start xman in three-button window: xman

- Open the manual page output stored in a given file: xman -helpfile

- Show both manual page and directory: xman -bothshown

xsel
X11 selection and clipboard manipulation tool.

- Use a command's output as input of the clip[b]oard (equivalent to Ctrl + C): echo 123 | xsel -ib

- Use the contents of a file as input of the clipboard: cat | xsel -ib

- Output the clipboard's contents into the terminal (equivalent to Ctrl + V): xsel -ob

- Output the clipboard's contents into a file: xsel -ob >

- Clear the clipboard: xsel -cb

- Output the X11 primary selection's contents into the terminal (equivalent to a mouse middle-click): xsel -op

yank
Read input from stdin and display a selection interface that allows a field to be selected and copied to the clipboard.

- Yank using the default delimiters (\f, \n, \r, \s, \t): | yank

- Yank an entire line: | yank -l

- Yank using a specific delimiter: | yank -d =

- Only yank fields matching a specific pattern: | yank -g ""

zile
Zile is a lightweight clone of the Emacs text editor

More information: https://www.gnu.org/software/zile/.

- Start a buffer for temporary notes, which won't be saved: zile

- Open a file: zile

- Save a file: Ctrl + X, Ctrl + S

- Quit: Ctrl + X, Ctrl + C

- Open a file at a specified line number: zile +

- Undo changes: Ctrl + X, U