Command

Meaning

>

Redirect output

>>

Append to file

<

Redirect input

<<

"Here" document (redirect input)

|

Pipe output

&

Run process in background.

;

Separate commands on same line

*

Match any character(s) in filename

?

Match single character in filename

[ ]

Match any characters enclosed

( )

Execute in subshell

` `

Substitute output of enclosed command

" "

Partial quote (allows variable and command expansion)

' '

Full quote (no expansion)

Quote following character

$var

Use value for variable

$$

Process id

$0

Command name

$n

nth argument (n from 0 to 9)

$*

All arguments as a simple word

#

Begin comment

bg

Background execution

break

Break from loop statements

cd

Change directories

continue

Resume a program loop

echo

Display output

eval

Evaluate arguments

exec

Execute a new shell

fg

Foreground execution

jobs

Show active jobs

kill

Terminate running jobs

newgrp

Change to a new group

shift

Shift positional parameters

stop

Suspend a background job

suspend

Suspend a foreground job

time

Time a command

umask

Set or list file permissions

unset

Erase variable or function definitions

wait

Wait for a background job to finish

sh

bash

ksh

csh

Meaning/Action

$

$

$

%

Default user prompt

>|

>|

>!

Force redirection

> file

2>&1

&> file or > file 2>&1

> file

2>&1

>& file

Redirect stdout and stderr to file

{ }

{ }

Expand elements in list

`command`

`command` or $(command)

$(command)

`command`

Substitute output of enclosed command

$HOME

$HOME

$HOME

$home

Home directory

~

~

~

Home directory symbol

~+, ~-, dirs

~+, ~-

=-, =N

Access directory stack

var=value

VAR=value

var=value

set

var=value

Variable assignment

export var

export VAR=value

export

var=val

setenv var

val

Set environment variable

${nnnn}

${nn}

More than 9 arguments can be referenced

"$@"

"$@"

"$@"

All arguments as separate words

$#

$#

$#

$#argv

Number of arguments

$?

$?

$?

$status

Exit status of the most recently executed command

$!

$!

$!

PID of most recently backgrounded process

$-

$-

$-

Current options

. file

source file or . file

. file

source file

Read commands in file

alias x='y'

alias x=y

alias x y

Name x stands for command y

case

case

case

switch or

case

Choose alternatives

done

done

done

end

End a loop statement

esac

esac

esac

endsw

End case or

switch

exit n

exit n

exit n

exit (expr)

Exit with a status

for/do

for/do

for/do

foreach

Loop through variables

set -f , set -o nullglob|dotglob|nocaseglob|noglob

noglob

Ignore substitution characters for filename generation

hash

hash

alias -t

hashstat

Display hashed commands (tracked aliases)

hash cmds

hash cmds

alias -t

cmds

rehash

Remember command locations

hash -r

hash -r

unhash

Forget command locations

history

history

history

List previous commands

ArrowUp+Enter or !!

r

!!

Redo previous command

!str

r str

!str

Redo last command that starts with "str"

!cmd:s/x/y/

r x=y cmd

!cmd:s/x/y/

Replace "x" with "y" in most recent command starting with "cmd", then execute.

if [ $i -eq 5

]

if [ $i -eq 5 ]

if ((i==5))

if ($i==5)

Sample condition test

fi

fi

fi

endif

End if statement

ulimit

ulimit

ulimit

limit

Set resource limits

pwd

pwd

pwd

dirs

Print working directory

read

read

read

$<

Read from terminal

trap 2

trap 2

trap 2

onintr

Ignore interrupts

unalias

unalias

unalias

Remove aliases

until

until

until

Begin until loop

while/do

while/do

while/do

while

Begin while loop