In recent Korn Shell ksh93, getopts can be more powerful than you think, it can :
- naturally parse short and long options with error management
- manage option value as optional, as mandatory or as numeric
- auto generate man page alike
This article will show how to use getopts in recent ksh93. If you have older ksh, read this other article instead.
(foobar_getopts.ksh zip file attachement in this article)
This script has been tested on ...
... Oracle Linux 7
... /bin/ksh --version #sh (AT&T Research) 93u+ 2012-08-01
foobar_getopts.ksh source code
foobar_getopts.ksh is a script example to show how to use getopts with short/long options in recent ksh93.
This script is also available for download at the end of the article.
#!/bin/ksh
#============================
# SET VARIABLES
#============================
unset SCRIPT_OPTS SCRIPT_ARGS USAGE
#== script info ==#
SCRIPT_VERS="0.0.1"
SCRIPT_AUTH="Michel VONGVILAY (www.uxora.com)"
SCRIPT_NAME="$(basename ${0})"
SCRIPT_TITL="foobar getopts example"
SCRIPT_DESC="this script is a example to show how to "
SCRIPT_DESC+="use getopts with short and long options."
#== script options ==#
SCRIPT_OPTS+="[f:foo?Set foo setting (default).]"
SCRIPT_OPTS+="[b:bar?Set bar setting.]"
SCRIPT_OPTS+="[B:barfoo]#[n:=2?Set barfoo to number n.]{
[0-5?low number]
[6-10?high number]
}"
SCRIPT_OPTS+="[F:foobar?Set foobar and foobar_name.]:?[name]"
SCRIPT_ARGS+=$'\n\nfiles ...\n\n'
#== program variables ==#
foo=1 bar=0
barfoo=2 foobar=0
foobar_name=
#============================
# OPTIONS WITH GETOPTS
#============================
#== set usage ==#
USAGE=$'[-?\n@(#)$Id: '${SCRIPT_NAME}' '${SCRIPT_VERS}$' $\n]'
USAGE+="[-author?${SCRIPT_AUTH}]"
USAGE+="[-copyright?www.uxora.com]"
USAGE+="[-license?GNU General Public License]"
USAGE+="[+NAME?${SCRIPT_NAME} - ${SCRIPT_TITL}]"
USAGE+="[+DESCRIPTION?${SCRIPT_DESC}]"
USAGE+="${SCRIPT_OPTS}"
USAGE+="${SCRIPT_ARGS}"
USAGE+=$'[+SEE ALSO?\awww.uxora.com\a]'
#== parse options ==#
while getopts "$USAGE" optchar ; do
case $optchar in
f) foo=1 bar=0 ;;
b) foo=0 bar=1 ;;
B) barfoo=${OPTARG}
[[ barfoo -lt 0 ]] && barfoo=0
[[ barfoo -gt 10 ]] && barfoo=10
;;
F) foobar=1
[[ "${OPTARG}" == "0" ]] && OPTARG=
foobar_name=${OPTARG:-"NOT_SET"}
;;
esac
done
shift $((${OPTIND} - 1))
#============================
# MAIN SCRIPT
#============================
#== print variables ==#
print foo=$foo bar=$bar
print barfoo=$barfoo
print foobar=$foobar foobar_name=$foobar_name
print files=$@
How to define an option
In this script, options are defined in #== script options ==# part with SCRIPT_OPTS variable as follow:
<short_opt> | One letter for short option |
<long_opt> | String for long option |
<description> | Option text description |
<value_type> | Use : for options that require a value.
Use # for options that require a numeric value.
Use :? and #? for options that allow value but not require. |
<value_name> | name of the value |
<default_value> | value by default |
Extra description can be added within { and } as it is done for barfoo option :
SCRIPT_OPTS+="[B:barfoo]#[n:=2?Set barfoo to number n.]{
[0-5?low number]
[6-10?high number]
}"
How to display help and man
getopts has already some predefined options :
-? display short usage--help display usage--man display full man page
And for some more specific information, these predefined options:
--about display version, author,copyright and licence information--version display version only--author display author only--copyright display copyright only--license display license only
# Display short help
$ ./foobar_getopts.ksh -?
<<--OUTPUT--
Usage: ./foobar_getopts.ksh [-fb] [-B n] [-F[name]] files ...
--OUTPUT--
# Display long help
$ ./foobar_getopts.ksh --help
<<--OUTPUT--
Usage: ./foobar_getopts.ksh [ options ] files ...
OPTIONS
-f, --foo Set foo setting (default).
-b, --bar Set bar setting.
-B, --barfoo=n Set barfoo to number n.
0-5 low number
6-10 high number
The default value is 2.
-F, --foobar[=name]
Set foobar and foobar_name. The option value may be omitted.
--OUTPUT--
# Display info and version
$ ./foobar_getopts.ksh --about
<<--OUTPUT--
version foobar_getopts.ksh 0.0.1
author Michel VONGVILAY (www.uxora.com)
copyright www.uxora.com
license GNU General Public License
--OUTPUT--
$ ./foobar_getopts.ksh --version
<<--OUTPUT--
version foobar_getopts.ksh 0.0.1
--OUTPUT--
# Display full man help
$ ./foobar_getopts.ksh --man
<<--OUTPUT--
NAME
foobar_getopts.ksh - foobar getopts example
SYNOPSIS
foobar_getopts.ksh [ options ] files ...
DESCRIPTION
this script is a example to show how to use getopts with short and long options.
OPTIONS
-f, --foo Set foo setting (default).
-b, --bar Set bar setting.
-B, --barfoo=n Set barfoo to number n.
0-5 low number
6-10 high number
The default value is 2.
-F, --foobar[=name]
Set foobar and foobar_name. The option value may be omitted.
SEE ALSO
www.uxora.com
IMPLEMENTATION
version foobar_getopts.ksh 0.0.1
author Michel VONGVILAY (www.uxora.com)
copyright www.uxora.com
license GNU General Public License
--OUTPUT--
Some examples
See how getopts manage itself options errors :
# Unknown option error
$ ./foobar_getopts.ksh -x
<<--OUTPUT--
./foobar_getopts.ksh: -x: unknown option
Usage: ./foobar_getopts.ksh [-fb] [-B n] [-F[name]] files ...
--OUTPUT--
# barfoo option without argument
# Expected argument error
$ ./foobar_getopts.ksh -B
<<--OUTPUT--
./foobar_getopts.ksh: -B: numeric n argument expected
Usage: ./foobar_getopts.ksh [-fb] [-B n] [-F[name]] files ...
--OUTPUT--
Now see getopts works without errors :
# foobar short option and barfoo short option
$ ./foobar_getopts.ksh -bF "Hello world" -B 6 file1 file2
<<--OUTPUT--
foo=0 bar=1
barfoo=6
foobar=1 foobar_name=Hello world
files=file1 file2
--OUTPUT--
# foobar short option without arg and barfoo long option
$ ./foobar_getopts.ksh -bF --barfoo 6 file1 file2
<<--OUTPUT--
foo=0 bar=1
barfoo=6
foobar=1 foobar_name=NOT_SET
files=file1 file2
--OUTPUT--
Better you test by yourself to see if it works and how it works.
Please leave comments and suggestions,
Michel.
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foobar_getopts.zip
Comments
I've been searching and I cannot find any documentation, I mean nothing about the "--man", "help" portion of this command in ksh93, ksh and BASH.
It's as if it was an undocumented feature.
I would like to know more about this.
Do you have anything to pass on?
Thanks
SCRIPT_DESC+=$'\nhave fun.'
When I echo "$USAGE", this generates new lines as intended.
But when I use the ./myscript --usage, all the text is collated.
Other formatting characters like \a on the other hand, do show in the --usage output
Any idea how I can format my description over several lines?
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