3.6. Differing Features

The following table displays features that are different among the three shells.

bash	ksh	tcsh	Meaning/action
$	$	%	Prompt.
>|	>|	>!	Force redirection.
		>>!	Force append.
> file 2>&1	> file 2>&1	>& file	Combine stdout and stderr.
>& file		>& file	Combine stdout and stderr.
' '	' '	' '	Substitute output of enclosed command.
$( )	$( )		Substitute output of enclosed command. (Preferred form.)
$HOME	$HOME	$home	Home directory.
var=value	var=value	set var=value	Variable assignment.
export var=val	export var=val	setenv var val	Set environment variable.
${nn}	${nn}		More than nine args can be referenced.
"$@"	"$@"		All args as separate words.
$#	$#	$#argv	Number of arguments.
$?	$?	$status	Exit status.
$!	$!		Last background Process ID.
$-	$-		Current options.
.file	.file	source file	Read commands in file.
alias x=y	alias x=y	alias x y	Name x stands for y.
case	case	switch/case	Choose alternatives.
cd ~-	cd ~-	popd/pushd	Switch directories.
popd/pushd		popd/pushd	Switch directories.
done	done	end	End a loop statement.
esac	esac	endsw	End case or switch.
exit [n]	exit [n]	exit [(expr)]	Exit with a status.
for/do	for/do	foreach	Loop through values.
echo -E	print -r	glob	Ignore echo escapes.
hash	alias -t	hashstat	Display hashed commands (tracked aliases).
hash cmds	alias -t cmds	rehash	Remember command locations.
hash -r	PATH=$PATH	unhash	Forget command locations.
history	history	history	List previous commands.
fc -s	r	!!	Redo previous command.
fc -s str	r str	!str	Redo command that starts with str.
fc -s x=y [cmd]	r x=y [cmd]	!cmd:s/x/y/	Edit command, then execute.
if ((i==5))	if ((i==5))	if ($i==5)	Sample if statement.
fi	fi	endif	End if statement.
ulimit	ulimit	limit	Set resource limits.
pwd	pwd	dirs	Print working directory.
read	read	$<	Read from standard input.
trap INTR	TRap INTR	onintr	Ignore interrupts.
unalias	unalias	unalias	Remove aliases.
until/do	until/do		Begin until loop.
while/do	while/do	while	Begin while loop.