topic Re: Case-statement and variables in Operating System - HP-UX

Case-statement and variables

Wessel Baptist — Wed, 14 Mar 2001 11:17:32 GMT

Why does this script respond whith "Wrong..." and "Right..." which I expected?

export POSSIBLE="6.6.01|6.6.02"
export CURRENT="6.6.01"
case $CURRENT in
$POSSIBLE)
echo "Right $CURRENT"
;;
(*)
echo "Wrong $CURRENT"
esac

Re: Case-statement and variables

Bill McNAMARA_1 — Wed, 14 Mar 2001 11:31:51 GMT

why don't you switch around the 6.6.01 in the
first export which may explain it.
Who cares anyway... it works!

Bill

Re: Case-statement and variables

Wessel Baptist — Wed, 14 Mar 2001 12:17:55 GMT

Sorry. I typed too fast, I forgot the word "NOT".
I mean: Why does this script respond whith "Wrong..." and NOT whith "Right..." which I expected?

Re: Case-statement and variables

John Palmer — Wed, 14 Mar 2001 12:52:58 GMT

Hi,

I think that it fails because of the order in which the shell processes the case statement.
The first thing that it does is to split the lines into tokens that are serarated by the standard set of metacharacters:-
space tab newline ; ( ) < > | &

Later it performs parameter substitution on $POSSIBLE but this is too late for it to correctly handle the | characters.

You can force the shell to re-evaluate the command with the 'eval' statement and indeed if you try:-

eval "

"

then you get the result that you expected. Quoting of this form can cause problems though.

Hope this helps,

Regards,
John