Common Features

Table 19-1 is a sampling of features that are common to bash and tcsh.

Table 19-1. Common shell features

Symbol/command

Meaning/action

>

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

! n

Repeat command number n

[ ]

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 (0<n_9)

$*

All arguments as simple words

#

Begin comment

Tab

Complete current word

bg

Background execution

break

Break from loop statements

cd

Change directory

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 (such as a shell created by su)

time

Time a command

umask

Set default file permissions for new files

unset

Erase variable or function definitions

wait

Wait for a background job ...

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