Add a user to the system

Adduser

Add a group to the system

Addgroup

Create an alias

alias

Search Help manual pages (man -k)

apropos

Search for and install software packages (Debian)

apt-get

Spell Checker

aspell

Find and Replace text, database sort/validate/index

awk

Strip directory and suffix from filenames

basename

GNU Bourne-Again SHell

bash

Arbitrary precision calculator language

bc

Send to background

bg

Exit from a loop •

break

Run a shell builtin

builtin

Compress or decompress named file(s)

bzip2

Display a calendar

cal

Conditionally perform a command

case

Display the contents of a file

cat

Change Directory

cd

Partition table manipulator for Linux

cfdisk

Change group ownership

chgrp

Change access permissions

chmod

Change file owner and group

chown

Run a command with a different root directory

chroot

System services (runlevel)

chkconfig

Print CRC checksum and byte counts

cksum

Clear terminal screen

clear

Compare two files

cmp

Compare two sorted files line by line

comm

Run a command - ignoring shell functions •

command

Resume the next iteration of a loop •

continue

Copy one or more files to another location

cp

Daemon to execute scheduled commands

cron

Schedule a command to run at a later time

crontab

Split a file into context-determined pieces

csplit

Divide a file into several parts

cut

Display or change the date & time

date

Desk Calculator

dc

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

dd

Data recovery tool

ddrescue

Declare variables and give them attributes •

declare

Display free disk space

df

Display the differences between two files

diff

Show differences among three files

diff3

DNS lookup

dig

Briefly list directory contents

dir

Colour setup for `ls'

dircolors

Convert a full pathname to just a path

dirname

Display list of remembered directories

dirs

Print kernel & driver messages

dmesg

Estimate file space usage

du

Display message on screen •

echo

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

egrep

Eject removable media

eject

Enable and disable builtin shell commands •

enable

Environment variables

env

Ethernet card settings

ethtool

Evaluate several commands/arguments

eval

Execute a command

exec

Exit the shell

exit

Automate arbitrary applications accessed over a terminal

expect

Convert tabs to spaces

expand

Set an environment variable

export

Evaluate expressions

expr

Do nothing, unsuccessfully

false

Low-level format a floppy disk

fdformat

Partition table manipulator for Linux

fdisk

Send job to foreground

fg

Search file(s) for lines that match a fixed string

fgrep

Determine file type

file

Search for files that meet a desired criteria

find

Reformat paragraph text

fmt

Wrap text to fit a specified width.

fold

Expand words, and execute commands

for

Format disks or tapes

format

Display memory usage

free

File system consistency check and repair

fsck

File Transfer Protocol

ftp

Define Function Macros

function

Identify/kill the process that is accessing a file

fuser

Find and Replace text within file(s)

gawk

Parse positional parameters

getopts

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

grep

Print group names a user is in

groups

Compress or decompress named file(s)

gzip

Remember the full pathname of a name argument

hash

Output the first part of file(s)

head

Display help for a built-in command •

help

Command History

history

Print or set system name

hostname

Print user and group id's

id

Conditionally perform a command

if

Configure a network interface

ifconfig

Stop a network interface

ifdown

Start a network interface up

ifup

Capture an X server screen and save the image to file

import

Copy files and set attributes

install

Join lines on a common field

join

Stop a process from running

kill

Kill processes by name

killall

Display output one screen at a time

less

Perform arithmetic on shell variables •

let

Make links between files

ln

Create variables •

local

Find files

locate

Print current login name

logname

Exit a login shell •

logout

Display lines beginning with a given string

look

Line printer control program

lpc

Off line print

lpr

Print a file

lprint

Abort a print job

lprintd

List the print queue

lprintq

Remove jobs from the print queue

lprm

List information about file(s)

ls

List open files

lsof

Recompile a group of programs

make

Help manual

man

Create new folder(s)

mkdir

Make FIFOs (named pipes)

mkfifo

Create an hybrid ISO9660/JOLIET/HFS filesystem

mkisofs

Make block or character special files

mknod

Display output one screen at a time

more

Mount a file system

mount

Manipulate MS-DOS files

mtools

Move or rename files or directories

mv

Mass Move and rename (files)

mmv

Networking information

netstat

Set the priority of a command or job

nice

Number lines and write files

nl

Run a command immune to hangups

nohup

Query Internet name servers interactively

nslookup

Open a file in its default application

open

Operator access

op

Modify a user password

passwd

Merge lines of files

paste

Check file name portability

pathchk

Test a network connection

ping

Stop processes from running

pkill

Restore the previous value of the current directory

popd

Prepare files for printing

pr

Printer capability database

printcap

Print environment variables

printenv

Format and print data •

printf

Process status

ps

Save and then change the current directory

pushd

Print Working Directory

pwd

Display disk usage and limits

quota

Scan a file system for disk usage

quotacheck

Set disk quotas

quotactl

ram disk device

ram

Copy files between two machines

rcp

Read a line from standard input •

read

Read from stdin into an array variable •

readarray

Mark variables/functions as readonly

readonly

Reboot the system

reboot

Rename files

rename

Alter priority of running processes

renice

Synchronize remote files via email

remsync

Exit a shell function

return

Reverse lines of a file

rev

Remove files

rm

Remove folder(s)

rmdir

Remote file copy (Synchronize file trees)

rsync

Multiplex terminal, run remote shells via ssh

screen

Secure copy (remote file copy)

scp

Merge two files interactively

sdiff

Stream Editor

sed

Accept keyboard input

select

Print numeric sequences

seq

Manipulate shell variables and functions

set

Secure File Transfer Program

sftp

Shift positional parameters

shift

Shell Options

shopt

Shutdown or restart linux

shutdown

Delay for a specified time

sleep

Find files

slocate

Sort text files

sort

Run commands from a file `.'

source

Split a file into fixed-size pieces

split

Secure Shell client (remote login program)

ssh

Trace system calls and signals

strace

Substitute user identity

su

Execute a command as another user

sudo

Print a checksum for a file

sum

Make a new name for a file

symlink

Synchronize data on disk with memory

sync

Output the last part of files

tail

Tape ARchiver

tar

Redirect output to multiple files

tee

Evaluate a conditional expression

test

Measure Program running time

time

User and system times

times

Change file timestamps

touch

List processes running on the system

top

Trace Route to Host

traceroute

Run a command when a signal is set(bourne)

trap

Translate, squeeze, and/or delete characters

tr

Do nothing, successfully

true

Topological sort

tsort

Print filename of terminal on stdin

tty

Describe a command •

type

Limit user resources •

ulimit

Users file creation mask

umask

Unmount a device

umount

Remove an alias •

unalias

Print system information

uname

Convert spaces to tabs

unexpand

Uniquify files

uniq

Convert units from one scale to another

units

Remove variable or function names

unset

Unpack shell archive scripts

unshar

Execute commands (until error)

until

Create new user account

useradd

Modify user account

usermod

List users currently logged in

users

Encode a binary file

uuencode

Decode a file created by uuencode

uudecode

Verbosely list directory contents (`ls -l -b')

v

Verbosely list directory contents (`ls -l -b')

vdir

Text Editor

vi

Report virtual memory statistics

vmstat

Execute/display a program periodically

watch

Print byte, word, and line counts

wc

Search the user's $path, man pages and source files for a program

whereis

Search the user's $path for a program file

which

Execute commands

while

Print all usernames currently logged in

who

Print the current user id and name (`id -un')

whoami

Retrieve web pages or files via HTTP, HTTPS or FTP

Wget

Send a message to another user

write

Execute utility, passing constructed argument list(s)

xargs

Print a string until interrupted

yes

Run a command script in the current shell

.

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