A

apt: Search for and install software packages (Debian)

apt-get: Search for and install software packages (Debian)

aptitude: Search for and install software packages (Debian)

aspell: Spell Checker

B

basename: Strip directory and suffix from filenames

bash: GNU Bourne-Again Shell. A Shell command lanuage

bc: Arbitrary precision calculator language

bg: Send to background

break: Exit from a loop

builtin: Run a shell builtin

bzip2: Compress or decompress named file(s)

C

cal: Display a calendar

case: Conditionally perform a command

cat: Concatenate and print (display) the content of files

cd: Change Directory

cfdisk: Partition table manipulator for Linux

chgrp: Change group ownership

chmod: Change access permissions

chown: Change file owner and group

chroot: Run a command with a different root directory

cksum: Print CRC checksum and byte counts

clear: Clear terminal screen

cmp: Compare two files

comm: Compare two sorted files line by line

command: Run a command – ignoring shell functions

continue: Resume the next iteration of a loop

cp: Copy one or more files to another location

cron: Daemon to execute scheduled commands

crontab: Schedule a command to run at a later time

csplit: Split a file into context-determined pieces

cut: Divide a file into several parts

D

date: Display or change the date & time

dc: Desk Calculator

dd: Convert and copy a file, write disk headers, boot records

ddrescue: Data recovery tool

declare: Declare variables and give them attributes

df: Display free disk space

diff: Display the differences between two files

diff3: Show differences among three files

dig: DNS lookup

dir: Briefly list directory contents

dircolors: Colour setup for `ls’

dirname: Convert a full path name to just a path

dirs: Display list of remembered directories

dmesg: Print kernel & driver messages

du: Estimate file space usage

E

echo: Display message on screen

egrep: Search file(s) for lines that match an extended expression

eject: Eject removable media

enable: Enable and disable builtin shell commands

env: Environment variables

ethtool: Ethernet card settings

eval: Evaluate several commands/arguments

exec: Execute a command

exit: Exit the shell

expect: Automate arbitrary applications accessed over a terminal

expand: Convert tabs to spaces

export: Set an environment variable

expr: Evaluate expressions

F

false: Do nothing, unsuccessfully

dirname: Convert a full path name to just a path

dirs: Display list of remembered directories

dmesg: Print kernel & driver messages

du: Estimate file space usage

G

gawk: Find and Replace text within file(s)

getopts: Parse positional parameters

grep: Search file(s) for lines that match a given pattern

groupadd: Add a user security group

groupdel: Delete a group

groupmod: Modify a group

groups: Print group names a user is in

gzip: Compress or decompress named file(s)

H

hash: Remember the full path name of a name argument

head: Output the first part of file(s)

help: Display help for a built-in command

history: Command History

hostname: Print or set system name

I

iconv: Convert the character set of a file

id: Print user and group id’s

if: Conditionally perform a command

ifconfig: Configure a network interface

ifdown: Stop a network interface

ifup: Start a network interface up

import: Capture an X server screen and save the image to file

install: Copy files and set attributes

J

jobs: List active jobs

join: Join lines on a common field

K

kill: Stop a process from running

killall: Kill processes by name

L

less: Display output one screen at a time

let: Perform arithmetic on shell variables

ln: Create a symbolic link to a file

local: Create variables

locate: Find files

logname: Print current login name

logout: Exit a login shell

look: Display lines beginning with a given string

lpc: Line printer control program

lpr: Off line print

lprint: Print a file

lprintd: Abort a print job

lprintq: List the print queue

lprm: Remove jobs from the print queue

ls: List information about file(s)

lsof: List open files

M

make: Recompile a group of programs

man: Help manual

mkdir: Create new folder(s)

mkfifo: Make FIFOs (named pipes)

mkisofs: Create an hybrid ISO9660/JOLIET/HFS filesystem

mknod: Make block or character special files

more: Display output one screen at a time

mount: Mount a file system

mtools: Manipulate MS-DOS files

mtr: Network diagnostics (traceroute/ping)

mv: Move or rename files or directories

mmv: Mass Move and rename (files)

N

netstat: Networking information

nice: Set the priority of a command or job

nl: Number lines and write files

nohup: Run a command immune to hangups

notify-send: Send desktop notifications

nslookup: Query Internet name servers interactively

O

open: Open a file in its default application

op: Operator access

P

passwd: Modify a password

paste: Merge lines of files

pathchk: Check file name portability

ping: Test a network connection

pkill: Stop processes from running

popd: Restore the previous value of the current directory

pr: Prepare files for printing

printcap: Printer capability database

printenv: Print environment variables

printf: Format and print data

ps: Process status

pushd: Save and then change the current directory

pwd: Print Working Directory

Q

quota: Display disk usage and limits

quotacheck: Scan a file system for disk usage

quotactl: Set disk quotas

R

rcp: Copy files between two machines

read: Read a line from standard input

readarray: Read from stdin into an array variable

readonly: Mark variables/functions as readonly

reboot: Reboot the system

rename: Rename files

renice: Alter priority of running processes

remsync: Synchronize remote files via email

return: Exit a shell function

rev: Reverse lines of a file

rm: Remove files

rmdir: Remove folder(s)

rsync: Remote file copy (Synchronize file trees)

S

screen: Multiplex terminal, run remote shells via ssh

scp: Secure copy (remote file copy)

sdiff: Merge two files interactively

sed: Stream Editor

select: Accept keyboard input

seq: Print numeric sequences

set: Manipulate shell variables and functions

sftp: Secure File Transfer Program

shift: Shift positional parameters

shopt: Shell Options

shutdown: Shutdown or restart Linux

sleep: Delay for a specified time

slocate: Find files

sort: Sort text files

source: Run commands from a file `.’

split: Split a file into fixed-size pieces

ssh: Secure Shell client (remote login program)

strace: Trace system calls and signals

sum: Print a checksum for a file

suspend: Suspend execution of this shell

symlink: Make a new name for a file

sync: Synchronize data on disk with memory

T

tail: Output the last part of file

tar: Tape ARchiver

tee: Redirect output to multiple files

test: Evaluate a conditional expression

time: Measure Program running time

times: User and system times

touch: Change file timestamps

top: List processes running on the system

traceroute: Trace Route to Host

trap: Run a command when a signal is set(bourne)

tr: Translate, squeeze, and/or delete characters

true: Do nothing, successfully

tsort: Topological sort

tty: Print filename of terminal on stdin

type: Describe a command

U

ulimit: Limit user resources

umask: Users file creation mask

umount: Unmount a device

unalias: Remove an alias

uname: Print system information

unexpand: Convert spaces to tabs

uniq: Uniquify files

units: Convert units from one scale to another

unset: Remove variable or function names

unshar: Unpack shell archive scripts

until: Execute commands (until error)

uptime: Show uptime

useradd: Create new user account

userdel: Delete a user account

usermod: Modify user account

users: List users currently logged in

V

v: Verbosely list directory contents (`ls -l -b’)

vdir: Verbosely list directory contents (`ls -l -b’)

vi: Text Editor

vim: Text Editor

vmstat: Report virtual memory statistics

W

wait: Wait for a process to complete

watch: Execute/display a program periodically

wc: Print byte, word, and line counts

whereis: Search the user’s $path, man pages and source files for a program

which: Search the user’s $path for a program file

while: Execute commands

who: Print all usernames currently logged in

whoami: Print the current user id and name (`id -un’)

wget: Retrieve web pages or files via HTTP, HTTPS or FTP

write: Send a message to another user

X

xargs: Execute utility, passing constructed argument list(s)

xdg-open: Open a file or URL in the user’s preferred application.

Y

yes: Print a string until interrupted

youtube-dl: Downloads a Youtube video

Z

zcmp: Minimal utilitie used to compare compressed files

zdiff: Minimal utilitie used to compare compressed files

zip: Is a simple easy-to-use utility used to package and compress (archive) files.