Linux in a Nutshell, Third Edition

Common Features

The following table is a sampling of features that are common to bash, csh, and tcsh. Note that tcsh is an enhanced version of csh; therefore, tcsh includes all features of csh, plus some others.

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.
` `	Substitute output of enclosed command.
" "	Partial quote (allows variable and command expansion).
\	Quote following character.
$ var	Use value for variable.
$$	Process ID.
$0	Command name.
$ n	nth argument (0<n≤9).
$*	All arguments.
#	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 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 job to finish.