bash getopt - main

21 Nov 2011


      Hi,
Has anyone done anything with GNU enhanced getopt in bash to process
incoming command line parameters?
My understanding is that I have the choice of using the built-in
"getopts" command within bash (on a CentOS 5.3 derivative distro),
which doesn't support long options (e.g. --long-option as opposed to
-l), or I can use the getopt (enhanced) 1.1.4 binary which lives in
/usr/bin/getopt.
I want to use long options, so I'm using the GNU getopt binary.  An
example script is below.  Note that there is one oddity - for
compatibility with some other related scripts, I need the first
parameter to be something else ... so the first few lines are intended
to munch $1 and pass all the remaining parameters to getopt.  I don't
think that should affect anything, but I've left it in as that's how
I'm currently testing it.
My problem is that I don't seem to be able to get the parsing to work
as I expect.  Specifically:
# ./cmd.sh . -i -o 1
input -i is -o
So the problem here is that it's quite happy to set the required
parameter for -i to be -o ... when actually I was expecting it to
catch that -i was missing a parameter.  I think I had this working
using getopts, but I need to be able to support long options now.
I've messed around a bit with several different ways of writing the
case script, but not managed to get it working any better.
So, idle question ... has anyone got a script like this where the
error checking is a bit more robust than the sample below?
Cheers,
Peter.
#!/bin/bash
paramArray=("${@}")
unset paramArray[0]
paramArray=("${paramArray[@]}")
getopt -T
if [ "$?" != "4" ]; then
  echo GNU enhanced getopt not detected.  Quitting ...
  exit 1;
fi
# Override defaults with incoming parameters, if specified
PN=`basename $0`
ARGS=`getopt --name "$PN" --longoptions
input:,output:,noshort:,verbose --options i:o: -- "${paramArray[@]}"`
if [ $? -ne 0 ]; then
  echo "Invalid option specified or expected parameter argument
missing.  Quitting ..."
  exit
fi
eval set -- "$ARGS"
while [ $# -gt 0 ]; do
    case "$1" in
        -i | --input)
                         echo input $1 is "$2";
                         shift;;
        -o | --output)
                         echo output $1 is "$2";
                         shift;;
        --noshort)
                         echo noshort $1 is "$2";
                         shift;;
        -v | --verbose)
                         VERBOSE=yes;
                         shift;;
        --)
                         shift;
                         break;;
    esac
    shift
done
exit;