HELP! (What's wrong with this sh scr - (nf)
ShanklandJA
jas at drutx.UUCP
Wed Apr 25 05:54:31 AEST 1984
> To guard against this, always (1) use double-quotes around
> your read-in strings and (2) pad such strings with a leading
> character to keep them from ever being null:
> if [ "X$ANSWER" = Xyes -o "X$ANSWER" = Xye -o "X$ANSWER" = Xy ]
I've always wondered about this curious custom of prefixing strings with X
(or whatever) to keep them from being null. Why? The System V Bourne
shell finds null strings perfectly acceptable; of course, they have to be
quoted, because the empty string is not the same as no string at all. In
any case, I find that:
if [ "$ANSWER" = yes -o "$ANSWER" = ye -o "$ANSWER" = y ]
works just fine, even when $ANSWER is null. Those X's look ugly to me.
Am I missing something?
Jim Shankland
..!ihnp4!druxy!jas
More information about the Comp.unix
mailing list