How do you use getopts?

Question

what is the easiest, most straight forward, way to use getopts in bash script.

if i have a script called: myscript and it CAN take the the arguments: -p -r -s -x

if argument x then exit
if argument p then echo "port 10"
if argument s then add 2+2
if argument r then echo env

This is a hypothetical script but I would just like to see an example of how this would be done.

possible duplicate of [Using getopts in bash shell script to get long and short command line options](http://stackoverflow.com/questions/402377/using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options) — , Oct 04 '11 at 13:46
I seen it, didnt help me. Thanks for pointing that out though — stackoverflow, Oct 04 '11 at 14:12

score 10 · Accepted Answer · answered Oct 04 '11 at 13:45

10

while getopts :xpsr opt; do
   case $opt in
     x ) exit                                ;;
     p ) echo port 10                        ;;
     s ) (( 2 + 2 ))                         ;;
     r ) echo env                            ;;
    \? ) echo "${0##*/}" [ -xpsr ]; exit 1   ;;
  esac
done

answered Oct 04 '11 at 13:45

Dimitre Radoulov

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sweet.. thanks Dimitre. But what does this last part do? \? ) echo "${0##*/}" [ -xpsr ]; exit 1 – stackoverflow Oct 04 '11 at 13:47
1

Prints the usage and exists if an invalid option is passed. – Dimitre Radoulov Oct 04 '11 at 13:49
No, I don't (perhaps I'm reading the questions too literally :)). Neither do I show how to deal with options' arguments ... – Dimitre Radoulov Oct 04 '11 at 14:20

score 3 · Answer 2 · edited Oct 04 '11 at 15:26

3

usage()
{
    echo "Usage: $0 [-o <offset>] [-h];"
    exit 0;
}

# -o (offset) need a value
# -h prints help
offset=0    # 0 is default offset

while getopts o:s opt
do
    case "$opt" in
    d)  offset="$OPTARG";; # changing offset
    s)  usage              # calls function "usage"
    \?) echo "$OPTARG is an unknown option"
        exit 1;; # all other options
    esac
done

shift $((OPTIND-1))

edited Oct 04 '11 at 15:26

Jonathan Leffler

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answered Oct 04 '11 at 13:46

Arnaud F.

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1

In which shell does that `shift $OPTIND-1` expression work? It normally has to be something like `$(($OPTIND - 1))`, doesn't it. – Jonathan Leffler Oct 04 '11 at 14:17
1

Or even: `$((OPTIND - 1))`, which is now standard. – Dimitre Radoulov Oct 04 '11 at 14:35

How do you use getopts?

2 Answers2

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