The Korn Shell, or ksh, is the Bourne-compatible shell created by David Korn
of AT&T Research. It offers a very powerful programming/scripting language
as well as a command shell.
- There are two major versions in use today. The 1988 release (ksh88)
and the 1993 release (ksh93).
- Most commercial UNIX vendors ship ksh88 as /bin/ksh.
- SunOS 5.x include ksh93 as /usr/dt/bin/dtksh. This particular build
integrates support with CDE.
- Slackware Linux includes ksh93 as /bin/ksh (starting with the 8.0
release).
- Red Hat Linux includes the Public Domain Korn Shell as /bin/ksh. This
is not a 100% ksh88 or ksh93 compatible shell.
| Command Shell | Programming Language |
- vi or Emacs command editing modes
- History file has configurable size and is shared across all shell
instances
- Process substitution
- Self generating documentation for shell builtins (text, HTML, or
troff).
- Command name completion in both editing modes.
- Job control - ksh allows for managing multiple jobs at the same
time.
- cd command - change to similarly named directories or completely
rewrite cd with your own shell function.
| - 100% Bourne shell compatible.
- Open multiple files at the same time.
- Keystroke and debugging traps builtin.
- Menu primitive (resizes according to the terminal size).
- Associative and indexed array support.
- Discipline functions
- Builtin integer arithmetic as well as access to math.h functions.
- Substring operators and recursive function support.
- Co-process facility
|
GNU bash, zsh, tcsh, and other open source shells offer great alternatives to
ksh. But there are some reasons you may want to run ksh over another shell.
- Guaranteed compatibility with future releases.
- ksh is common on commercial UNIX systems.
- Same across all platforms it supports.
- Includes some language features not found in other shells.
The following examples are to be executed from a ksh command prompt.
print ${.sh.version}
This works in ksh93 only.
what /bin/ksh | grep Version
This works only on systems with the what command.
Download ast-base, ast-base-locale, and INIT.
$ cd /tmp
$ mkdir -p ast/lib/package/tgz
$ cp ast-base* ast-base-locale* INIT* ast/lib/package/tgz
$ cd ast
$ gzip -dc lib/package/tgz/INIT* | tar -xvf -
$ bin/package read
$ bin/package make
(This command is also used to
modify options, see the ksh man page for descriptions.)
set -o
history [ -{num} | {num} {num} | {num} ]
That's limit list to num, display from num to num, and show
commands starting from num.
r [ {num} | {string cmd starts with} ]
Recall a previous command by its history number or by
typing in the first few characters of its name.
[esc] [=]
Display list of pathnames that result from expanding the
word under the cursor.
[esc] [esc]
Append characters to the word under the cursor to
complete the pathname of an existing file.
[esc] [*]
Replace words under the cursor with the list of pathnames
that result from expanding the word.
[=]
Display list of pathnames that result from expanding the
word under the cursor.
[\]
Append characters to the word under the cursor to
complete the pathname of an existing file.
[*]
Replace words under the cursor with the list of pathnames
that result from expanding the word.
All ksh builtins have self-generated text, HTML, and troff
documentation. Just type --help, --man, or --html for the appropriate
version.
export PS1='${USER}@$(hostname):${PWD/#$HOME/~}\$ '
typeset -A Keytable
trap 'eval "${Keytable[${.sh.edchar}]}"' KEYBD
2.13. Quickly change to /usr/openwin/bin from
/usr/local/bin.
$ pwd
/usr/local/bin
$ cd local openwin
/usr/openwin/bin
$ pwd
/usr/openwin/bin
2.14. Create, modify, and get information on variables and
functions.
typeset --help | more
PS3='Pick one of the above: '
TMOUT=10
select i in list edit quit
do
case $i in
list) cat "$foo" ;;
edit) ${EDITOR-vi} "$foo" ;;
quit) break ;;
"") print -u2 you must select one of the above ;;
esac
done
FPATH=$HOME/.ksh.functions
autoload foobar
paste> (cut -f1 file1)> (cut -f3 file2) | tee <(pro1) <(pro2)
Using the Korn Shell 
