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UNIX in a Nutshell: System V Edition

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The UNIX Shell: An Overview
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3.5 Differing Features

The table below is a sampling of features that are different among the three shells.

sh ksh csh Meaning/Action
$ $ % Prompt.
>! Force redirection.
>>! Force append.
> file 2>&1 > file 2>&1 >& file Combine stdout and stderr.
{ } Expand elements in list.
` ` $( ) ` ` Substitute output of enclosed command.
$HOME $HOME $home Home directory.
~ ~ Home directory symbol.
var = value var = value set var = value Variable assignment.
export var export var = val setenv var val Set environment variable.
${ nn } More than 9 args can be referenced.
"$@" "$@" All args as separate words.
$# $# $#argv Number of arguments.
$? $? $status Exit status.
$! $! Background exit status.
$- $- Current options.
.   file .   file source file Read commands in file .
alias x = y alias x y Name x stands for y .
case case switch/case Choose alternatives.
cd ~- 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 variables.
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 unhash Forget command locations.
history history List previous commands.
r !! Redo previous command.
r str ! str Redo command that starts with str .
r x = y cmd ! cmd :s/ x / y / Edit command, then execute.
if [ $i -eq 5 ] if ((i==5)) if ($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 terminal.
trap 2 trap 2 onintr Ignore interrupts.
unalias unalias Remove aliases.
until until Begin until loop.
while/do while/do while Begin while loop.

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3.4 Common Features Book Index 4. The Bourne Shell and Korn Shell

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