On Sat, May 05, 2001 at 04:35:02PM -0700, Karsten M. Self wrote: > > > > Some bourne shells don't like testing variables that don't exist yet. > > That's precisely what we're trying to test.
where you run in to trouble really is when you don't quote the
variable, for example:
if [ $FOO = bar ] ; then
echo true
fi
if $FOO is unset you get a shell error about unary operator. because
the above translates to:
if [ = bar ] ; then
echo true
fi
which is not valid.
if you quite the variable you get:
if [ "" = bar ] ; then
echo true
fi
the quotes of course are removed, but they show here that an actual
null is being tested for equality with `bar'.
--
Ethan Benson
http://www.alaska.net/~erbenson/
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