shell之间的比较

Feature	C/TC	Bourne	Bash	Korn
Variables:
Assigning values to local variables	set x = 5	x=5	x=5	x=5
Assigning variable attributes			declare or typeset	typeset
Assigning values to environment variables	setenv NAME Bob	NAME='Bob'; export NAME	export NAME='Bob'	export NAME='Bob'
Read-Only Variables:
Accessing variables	echo $NAME set var = net echo ${var}worknetwork	echo $NAME var=netecho ${var}worknetwork	echo $NAME var=netecho ${var}worknetwork	echo $NAME or print $NAME var=netprint ${var}worknetwork
Number of characters	echo $%var (tcsh only)	N/A	${#var}	${#var}
Special Variables:
PID of the process	$$	$$	$$	$$
Exit status	$status, $?	$?	$?	$?
Last background job	$! (tcsh only)	$!	$!	$!
Arrays:
Assigning arrays	set x = ( a b c )	N/A	y[0]='a'; y[2]='b'; y[2]='c' fruit=(apples pears peaches plums)	y[0]='a'; y[1]='b'; y[2]='c' set –A fruit apples pears plums
Accessing array elements	echo $x[1] $x[2]	N/A	echo ${y[0]} ${y[1]}	print ${y[0]} ${y[1]}
All elements	echo $x or $x[*]	N/A	echo ${y[*]}, ${fruit[0]}	print ${y[*]}, ${fruit[0]}
No. of elements	echo $#x	N/A	echo $y{#[*]}	print ${#y[*]}
Command Substitution:
Assigning output of command to variable	set d = `date`	d=`date`	d=$(date) or d=`date`	d=$(date) or d=`date`
Accessing values	echo $d echo $d[1], $d[2], ...echo $#d	echo $d	echo $d	print $d
Command Line Arguments (Positional Parameters):
Accessing	$argv[1], $argv[2] or $1, $2 ...	$1, $2 ... $9	$1, $2, ... ${10} ...	$1, $2, ... ${10} ...
Setting positional parameters	N/A	set a b c set `date`echo $1 $2 ...	set a b c set `date` or set $(date)echo $1 $2 ...	set a b c set `date` or set $(date)print $1 $2 ...
No. of command line arguments	$#argv $# (tcsh)	$#	$#	$#
No. of characters in $arg[number]	$%1, $%2, (tcsh)	N/A	N/A	N/A
Metacharacters for Filename Expansion:
Matches for:
Single character	?	?	?	?
Zero or more characters	*	*	*	*
One character from a set	[abc]	[abc]	[abc]	[abc]
One character from a range of characters in a set	[a–c]	[a–c]	[a-c]	[a–c]
One character not in the set	N/A (csh) [^abc] (tcsh)	[!abc]	[!abc]	[!abc]
? matches zero or one occurrences of any pattern in the parentheses. The vertical bar represents an OR condition; e.g., either 2 or 9. Matches abc21, abc91, or abc1.			abc?(2|9)1	abc?(2|9)1
Filenames not matching a pattern	^pattern (tcsh)
I/O Redirection and Pipes:
Command output redirected to a file	cmd > file	cmd > file	cmd > file	cmd > file
Command output redirected and appended to a file	cmd >> file	cmd >> file	cmd >> file	cmd >> file
Command input redirected from a file	cmd < file	cmd < file	cmd < file	cmd < file
Command errors redirected to a file	(cmd > /dev/tty)>&errors	cmd 2>errors	cmd 2> file	cmd 2> errors
Output and errors redirected to a file	cmd >& file	cmd > file 2>&1	cmd >& file or cmd &> file or cmd > file 2>&1	cmd > file 2>&1
Assign output and ignore noclobber	cmd >| file	N/A	cmd >| file	cmd >| file
here document	cmd << EOF inputEOF	cmd << EOF inputEOF	cmd << EOF inputEOF	cmd << EOF inputEOF
Pipe output of one command to input of another command	cmd | cmd	cmd | cmd	cmd | cmd	cmd | cmd
Pipe output and error to a command	cmd |& cmd	N/A	N/A	(See coprocesses)
Coprocess	N/A	N/A	N/A	command |&
Conditional statement	cmd && cmd cmd || cmd	cmd && cmd cmd || cmd	cmd && cmd cmd || cmd	cmd && cmd cmd || cmd
Reading from the Keyboard:
Read a line of input and store into variable(s)	set var = $< set var = 'line'	read var read var1 var2...	read var read var1 var2...readread -p promptread -a arrayname	read var read var1 var2...readread var?"Enter value"
Arithmetic:
Perform calculation	@ var = 5 + 1	var=`expr 5 + 1`	(( var = 5 + 1 )) let var=5+1	(( var = 5 + 1 )) let var=5+1
Tilde Expansion:
Represent home directory of user	~username	N/A	~username	~username
Represent home directory	~	N/A	~	~
Represent present working directory	N/A	N/A	~+	~+
Represent previous working directory	N/A	N/A	~-	~–
Aliases:
Create an alias	alias m more	N/A	alias m=more	alias m=more
List aliases	alias		alias, alias -p	alias, alias –t
Remove an alias	unalias m	N/A	unalias m	unalias m
History:
Set history	set history = 25	N/A	automatic or HISTSIZE=25	automatic or HISTSIZE=25
Display numbered history list	history		history, fc -l	history, fc –l
Display portion of list selected by number	history 5		history 5	history 5 10 history –5
Re-execute a command	!! (last command) !5 (5th command)!v (last command starting with v)		!! (last command) !5 (5th command)!v (last command starting with v)	r (last command) r5 (5th command) r v (last command starting with v)
Set interactive editor	N/A (csh) bindkey -v or bindkey -e (tcsh)	N/A	set -o vi set -o emacs	set -o vi set -o emacs
Signals:
Command	onintr	trap	trap	trap
Initialization Files:
Executed at login	.login	.profile	.bash_profile	.profile
Executed every time the shell is invoked	.cshrc	N/A	BASH_ENV=.bashrc (or other filename) (bash 2.x) ENV=.bashrc	ENV=.kshrc (or other filename)
Functions:
Define a function	N/A	fun() { commands; }	function fun { commands; }	function fun { commands; }
Call a function	N/A	fun fun param1 param2 ...	fun fun param1 param2 ...	fun fun param1 param2 ...
Programming Constructs:
if conditional	if ( expression ) then commands endifif { ( command ) } then commandsendif	if [ expression ] then commands fiif command then commandsfi	if [[ string expression ]] then commandsfiif (( numeric expression ))then commandsfi	if [[ string expression ]] then commandsfiif (( numeric expression ))then commandsfi
if/else conditional	if ( expression ) then commandselse commandsendif	if command then commandselse ...fi	if command then commandselse ...fi	if command then commandselse ...fi
if/else/elseif conditional	if (expression) then commandselse if (expression) then commands else commands endif	if command then commandselif commandthen commands else commands fi	if command then commandselif command then commandselse commandsfi	if command then commandselif command then commandselse commandsfi
goto	goto label ...label:	N/A	N/A	N/A
switch and case	switch ("$value") case pattern1: commands breakswcase pattern2: commands breaksw default: commands breakswendsw	case "$value" in pattern1) commands ;;pattern2) commands ;;*) commands ;;esac	case "$value" in pattern1) commands ;;pattern2) commands ;;*) commands ;;esac	case "$value" in pattern1) commands ;;pattern2) commands ;;*) commands ;;esac
Loops:
while	while (expression) commandsend	while command do commanddone	while command do commanddone	while command do commandsdone
for/foreach	foreach var (wordlist) commandsend	for var in wordlist do commandsdone	for var in wordlist do commandsdone	for var in wordlist do commandsdone
until	N/A	until command do commandsdone	until command do commandsdone	until command do commandsdone
repeat	repeat 3 "echo hello" hellohello hello	N/A	N/A	N/A
select	N/A	N/A	PS3="Please select a menu item" select var in wordlistdo commandsdone