[Help-bash] Solved: Re: Distinguish between unset and empty variables in loop.

[Christof Warlich]

Just for the record, here is a solution of the problem:

        xxx=hi;
        yyy="";
        unset zzz;
        for i in xxx yyy zzz; do
                (set -o posix; set | grep -q "^$i=") || eval "$i=default"; echo 
$i=${!i};
        done

It prints

        xxx=hi
        yyy=
        zzz=default

as desired.

This is clearly a hack, but it just works, so who cares.

Cheers,

Chris