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From: Zahemszky Gabor <zgabor@CoDe.hu>
Message-Id: <199705120833.KAA00648@CoDe.hu>
Subject: Re: getopts
To: freebsd-questions@freebsd.org (FreeBSD questions)
Date: Mon, 12 May 1997 10:33:14 +0200 (MET DST)
Cc: un_x@anchorage.net
In-Reply-To: <Pine.BSF.3.95q.970511082828.18804A-100000@aak.anchorage.net> from Steve Howe at "May 11, 97 08:51:46 am"
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> 
> ok - i finally figured this out, and am posting my answer
> for anyone else that may be interested ...  there are a few
> tricky aspects of it (w/thanks to zgabor).
> -------------------------------------------------------------------------
> while getopts abc i; do
> 	case $i in
> 		a)	a=$i; echo A;;
> 		b)	b=$i; echo B;;
> 		c)	c=$i; echo C;;
> 		?)	e=$i; echo huh?;;
> 	esac
> done
> shift $(($OPTIND - 1))
> echo $a + $b + $c
> echo $0 $1

Hm.  
	?)	e=$OPTARG ; echo $OPTARG 'is an illegal option or an option
	without a parameter' ;;

And it would be better :
while getopts :abc i ; do
--------------^
In that way, you suppress the getopts' own error message, and get back
a '?' if you give an illegal option, and get back a ':' if you give a legal
option which needs a parameter, but it's missing, eg:

Call the script with -x -a -b -c, but the -x is illegal, and it's missing
the -c's parameter.

while getopts :abc: i ; do
	case "$i" in
		a)	echo option A ;;
		b)	echo option B ;;
		c)	echo option C with argumentum "$OPTARG" ;;
		\?)	echo illegal option "$OPTARG" ;;
		:)	echo "$OPTARG" option requires an argument ;;
		?)	echo 'What an earth is it?  Getopts cannot return
		with anything else' ;;
	esac
done

Well, on 2.1.5, sh's getopts cannot handle this, I don't know the newer one.
(But it's the way, getopts works in other shells.  Get pdksh, and man it.
It has a very good description about getopts - and about any other shell
construct.)

> -------------------------------------------------------------------------
> this script may be invoked as
> "script -abc   file" or
> "script -bc -a file" or
> "script -c -cc file" ... (C will echo 3x)
> 
> the "shift" statement MUST occur
> as above, or any "file" will not
> appear in "$1" when option parsing
> is done.  you CANNOT replace the
> "shift" statement above with
> 
> "a) a=$i; echo A; shift;;"
> 
> type case statements, otherwise
> 
> "script -abc file"
> 
> where "-abc" is "$1"
> will get shifted 3x, and
> you will lose "file".
> 
> any number of options in the getopts statement
> may be followed by a colon, in which case,
> $OPTARG will contain the options argument,
> which should be "caught" by its corresponding
> options "case" statement.
> 
> the "e" case statement will trap any errors.
> 
> i don't know if "getopts" can be used
> without a "while" statement ...

Yes it can, but it's not too effective ;-).

Gabor
--
#!/bin/ksh
Z='21N16I25C25E30, 40M30E33E25T15U!' ;IFS=' ABCDEFGHIJKLMNOPQRSTUVWXYZ ';set $Z;for i { [[ $i = ? ]]&&print $i&&break;[[ $i = ??? ]]&&j=$i&&i=${i%?};typeset -i40 i=8#$i;print -n ${i#???};[[ "$j" = ??? ]]&&print -n "${j#??} "&&j=;typeset +i i;};IFS=' 0123456789 ';set $Z;X=;for i { [[ $i = , ]]&&i=2;[[ $i = ?? ]]||typeset -l i;X="$X $i";typeset +l i;};print "$X"