Why do people use: if [ "x$FOO" = "x" ] .... ?

[Henry Spencer]

> Suppose you are asking for confirmation and you want any of "y", "ye",
> or "yes", or "yo" or anything else starting with "y" to mean "yes",
> and anything starting with "n" to mean "no". ...
> 
> Using "$answer" doesn't work unless you explicitly list ALL of the choices,
> since "*" isn't expanded inside strings...

Huh?  The following has always worked perfectly for us, on both V7
and SysV shells:

	case "$answer"
	in
		y*)
		echo yes
		;;

		n*)
		echo no
		;;

		*)
		echo huh
		;;
	esac

Just to be doubly sure, I just wrote out the above example and tried
it.  Works fine.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry