3

I have searched a couple of days and still didn't found the answer. I hope that you can point me in right direction.

I would like to know how to write a bash script with a options, that can be called in one row, such as: script.sh -a -b -c. Parameters which aren't chosen are ignored.

Menu/options should be like:

-a description: something
-b description: something else
-c description: something different
-d description: something..

is there any way to do this?

7

The usual way of handling switches and arguments is with the getopts function. In bash this is a builtin and you can find information about it in the bash man page (man bash).

Essentially, you declare a string that tells getopts what parameters to expect, and whether they should have an argument. It's getopts that handles bunched parameters (eg -abc being equivalent to -a -b -c) and the parsing of the command line. At the end of the getopts processing you have the remainder of the command line to handle as you see fit.

A typical script segment could look something like this

ARG_A= FLAG_B= FLAG_C=
while getopts 'a:bc' OPT    # -a {argument}, -b, -c
do
    case "$OPT" in
        a)    ARG_A="$OPTARG" ;;
        b)    FLAG_B=yes ;;
        c)    FLAG_C=yes ;;
        *)    echo "ERROR: the options are -a {arg}, -b, -c" >&2; exit 1 ;;
    esac
done
shift $(($OPTIND - 1))

echo "Remaining command line: $*"

You can add ? as a command option if you want a nice usage message. Remember that in the case block you would need to quote it or prefix it with a backslash so it's treated as a literal.

If you're wanting to run this under a different shell that doesn't have the builtin, or if you want to use long arguments such as --verbose instead of just -v take a look at the getopt utility. This is not a builtin but has been written to deliver in the more sophisticated situation.

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1

You don't have to use any Bash-specific features to do this:

#!/bin/sh
while true
do
    case "$1" in
        -a)  echo Saw -a!  ;;
        -b)  echo Saw -b!  ;;
        -c)  echo Saw -c!  ;;
        -?)  cat <<USAGE
usage: $0 [-a] [-b] [-c] args

    You cannot currently combine options, as with -ac.
USAGE
            exit 1
            ;;
        *)
            echo End of options!
            break;
            ;;
    esac

    shift       # toss current $1; we're done with it now
done

for p in "$@"
do
    echo "Non-option argument: '$p'"
done

Unlike the code in roaima's answer, mine is portable shell script code. It will run on any Bourne type Unix shell going back to about 1980 or so.

I think the -? handler answers your "menu" requirement. The <<USAGE construct is called a heredoc.

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