Bash: how to handle --options?

humbletech99 · 08-31-2006, 11:15 AM

I've tried to handle --options in the long gnu style format using the builtin getopts but it doesn't like it.

I know the external getopt does have an -l switch for this but the external is deprecated and I'd rather avoid using it.

I'm creating a wrapper script. What I need it to be able to take any number of arguments and then if a certain switch or two is passed, to tell the user off and exit 1. But I want everything to pass through to the program if one of the dangerous switches wasn't passed. So it needs to be able to not croak when a user passes --help to the underlying program.

Any ideas?

acid_kewpie · 08-31-2006, 01:19 PM

the standard getopt in bash does handle long options just fine, one of the standard examples that comes with it in the util-linux package on my fc5 system is...

Code:

TEMP=`getopt -o ab:c:: --long a-long,b-long:,c-long:: \
     -n 'example.bash' -- "$@"`

if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi

# Note the quotes around `$TEMP': they are essential!
eval set -- "$TEMP"

while true ; do
        case "$1" in
                -a|--a-long) echo "Option a" ; shift ;;
                -b|--b-long) echo "Option b, argument \`$2'" ; shift 2 ;;
                -c|--c-long)
                        # c has an optional argument. As we are in quoted mode,
                        # an empty parameter will be generated if its optional
                        # argument is not found.
                        case "$2" in
                                "") echo "Option c, no argument"; shift 2 ;;
                                *)  echo "Option c, argument \`$2'" ; shift 2 ;;
                        esac ;;
                --) shift ; break ;;
                *) echo "Internal error!" ; exit 1 ;;
        esac
done
echo "Remaining arguments:"
for arg do echo '--> '"\`$arg'" ; done

humbletech99 · 08-31-2006, 06:42 PM

err, getopt is not technically bash, it's an external. And yes it can handle long options but it's older and deprecated in favour of the getopts internal builtin.

it looks to me like you're still parsing it manually.

thanks for the tip, I will try this out.

since I'm just writing a wrapper to stop a couple flags going through to a command, I've done a quick and nice looking thing.

Code:

params="$@"

until [ -z $1 ]
    do
    if [ "$1" == "-d" ]
       then
       echo "you are not allowed to use the -d switch... blah blah" >&2
       exit 1
    fi
    etc
    shift
done

command "$params"

Arvid Requate · 10-07-2011, 07:20 AM

Actually the Bash builtin getopts function can be used to parse long options by putting a dash character followed by a colon into the optspec. For an example script see:

http://stackoverflow.com/questions/4...680682#7680682

acid_kewpie · 10-07-2011, 07:21 AM

over 5 years old. no more replies please.