[Chapter 3] 3.4 Common Features

3.4 Common Features

The table below is a sampling of features that are common to the Bourne, Korn, and C shells. Note that the Korn shell is an enhanced version of the Bourne shell; therefore, the Korn shell includes all features of the Bourne shell, plus some others. The commands bg , fg , jobs , stop , and suspend are available only on systems that support job control.

Symbol/	Meaning/Action
Command
>	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`	`n` th argument (0<`n` <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.