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Linux in a Nutshell, Fourth Edition by Aaron Weber, Stephen Figgins, Ellen Siever

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Common Features

The following table is a sampling of features that are common to bash and tcsh.

Symbol/Command

Meaning/Action

>

Redirect output.

>>

Append output 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.

" "

Partial quote (allows variable and command expansion).

' '

Preserve literal value of enclosed characters.

\

Quote following character.

$ var

Use value for variable.

$$

Process ID.

$0

Command name.

$ n

nth argument (0<n≤9).

$*

All arguments.

$?

Exit status.

#

Begin comment.

Tab

Complete current word.

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 or other program.

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.

umask

Set or list permissions on files to be created.

unset

Erase variable or function definitions.

wait

Wait for a background ...

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