This came up on another list. The problem involves testing existence of
a Unix shell variable from another program with limited system
interaction features.
I usually write this in bash as:
if [ x${MYVAR} = x ]; then
echo 'MYVAR doesn't exist (or isn't set)'
else echo "MYVAR exists, value: $MYVAR"
fi
...which essentially checks whether or not the variable has a non-null
value. But would report that $MYVAR doesn't exist if in fact it was set
equal to "".
In contrast, csh and derivatives have:
$?MYVAR
...which allows testing of presence of a variable.
...but I'm not aware of a similar bash/korn/bourne feature. Anyone?
--
Karsten M. Self <kmself@ix.netcom.com> http://kmself.home.netcom.com/
What part of "Gestalt" don't you understand? There is no K5 cabal
http://gestalt-system.sourceforge.net/ http://www.kuro5hin.org
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