A

apropos : Search Help manual pages (man -k)

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

aptitude : Search for and install software packages (Debian)

aspell : Spell Checker

awk : Find and Replace text, database sort/validate/index

 

B

basename : Strip directory and suffix from filenames

bash : GNU Bourne-Again SHell

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

chkconfig : System services (runlevel)

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 pathname 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

fdformat : Low-level format a floppy disk

fdisk : Partition table manipulator for Linux

fg : Send job to foreground

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

file : Determine file type

find : Search for files that meet a desired criteria

fmt : Reformat paragraph text

fold : Wrap text to fit a specified width.

for : Expand words, and execute commands

format : Format disks or tapes

free : Display memory usage

fsck : File system consistency check and repair

ftp : File Transfer Protocol

function : Define Function Macros

fuser : Identify/kill the process that is accessing a file

 

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 pathname 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 user 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

ram : ram disk device

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

su : Substitute user identity

sudo : Execute a command as another user

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

uuencode : Encode a binary file

uudecode : Decode a file created by uuencode

 

V

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

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

vi : 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.

yes : Print a string until interrupted.