Use Variable with multiple options in Case statement

Question

Is it possible to do something like the following (and how ?)(,resp. why not ?):

MATCH="--opt1 | --opt2"
while true ; do
    case $1 in
        $MATCH)
             echo "option $2" found;
             shift 2;;
        *)
             unknown option; exit 1;
    esac
done

For reason I dont understand this doesnt work. However, having only one alternative like MATCH="--opt1" is fine.

Edit 1: possible Solution

Instead of going with case statement one could simply check if the given option occurs in a string of multiple allowed options, for instance by using grep and if. To do it full dynamically one could consider the follwoing solution, which might also combined with or embedded within case statement:

while true ; do
if [ -n "$(echo $MATCHES|grep -- $1)" ]; then
    echo "found option $1 with value $2"
    shift 2
fi
done

chepner · Accepted Answer · 2013-10-07 12:31:28Z

10

The pipe character, when embedded in a parameter value, is treated literally, not as syntax. You'll have to use multiple strings:

while true; do
    case $1 in
       $MATCH1 | $MATCH2 )
       # etc

answered Oct 7, 2013 at 12:31

chepner

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3 Comments

fedorqui Over a year ago

Good one. So it only matches when the parameter given is exactly "--opt1 | --opt2"

user1240076 Over a year ago

which means, that the "Match-clause" cannot be created generically ?!

chepner Over a year ago

@user1240076 Correct. Your code is clearer when you keep data and synxtax/operators separate.

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