getopts with optional parameters

[Jaris Detroye]

I would like to use the 'getopts' command to parse my command line, but *ALL* options are optional.
So far I have been unable to figure out how to tell the 'getopts' command the two options which are valid e.g. 'r' & 'n', but that they are optional and it is valid to call the script with no options at all.

Any suggestions?

[Hemanth Gurunath Basrur]

Hello,

Refer to http://nscp.upenn.edu/aix4.3html/cmds/aixcmds2/getopts.htm

for examples to specify valid options.

Also, refer to getopts(1) @

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-60103/B2355-60103_top.html&con=/hpux/onlinedocs/B2355-60103/00/01/152-con.html&toc=/hpux/onlinedocs/B2355-60103/00/01/152-toc.html&searchterms=command%7cgetopts&queryid=20031010-212500

HTH.

Regards,
Hemanth

[Jdamian]

'but *ALL* options are optional' --> what does it mean ?.... Of course, all options are optional.

[Graham Cameron_1]

I think you need something like
--
--
while getopts r:n name
do
case ${name} in
r)
...CODE TO SET "r" FLAGS HERE;;
n)
...CODE TO SET "n" FLAGS HERE;;
?)
...CODE TO HANDLE INVALID OPTIONS HERE ;;
esac
done
--
in your "...CODE" sections you can refer to ${OPTARG}, so that
if your program is invoked with "-r fred", then OPTARG would
contain "fred".
Hope you get the idea
-- Graham

[Bhuvaneswari Selvaraj]

int
main (int argc, char *argv[])
{
int c=0,rflag=0, nflag=0;
while (( c = getopt(argc,argv,":r:n:")) != -1 ) {
switch (c) {
case 'r':
printf("Option r chosen");
rflag++;
break;
case 'n':
printf("Option n chosen");
nflag++;
break;
case '?':
printf ("Error");
break;
}
}
}

if (rflag>1)
printf ("Error");
if (nflag >1)
printf("Error");
Hope this helps...

[Jaris Detroye]

The problem that I see is this, if I get a '?' in the $OPTARG when either an invalid option is used, or when no options at all are used, then it is up to me to detirmine which case it is. I was hoping that I could aviod having to do that.

[Graham Cameron_1 · Accepted solution]

YOu can examine $OPTIND, which is initialised to 1, and incremented as arguments are processed. It it is still 1, at the end of the while loop, then no arguments were processed.
Also, processing will drop through to the "?)" clause whenever an unexpected argument is found, ie anything except 'r', 'n'.
-- Graham

[john korterman]

Hi,
I tried to experiment a little; perhaps you can use it...

regards,
John K.

[Jaris Detroye]

Graham you hit it right on the head. That did not occur to me. Good job, thanks.

John, that is one approach I never thought of. Encasing the getopts command within a case statement hmmm..... might have to try that one out sometime.

Cudos to all!!!