From: Akim Demaille <[EMAIL PROTECTED]>
Date: 24 May 2000 10:41:53 +0200
Akim> expr has a bad reputation
Paul> Its syntax is awkward -- was that what you were thinking about?
Nope, I was referring to the portability. And precisely about the
syntax, is `match string expr' portable?
No. A portable shell script cannot pass the four words "match",
"length", "substr", or "index" to expr. For example, "expr match :
match" is not allowed. This is another good reason to prefix the
operands of : with X.
Paul> if expr "x$ac_package" : '.*[^-a-zA-Z0-9_]' >/dev/null; then
My understanding of the `x' here is to avoid problems with $ac_package
being a built-in of expr, right?
Yes. It's not just the four words mentioned above; it's also
operators like '-' or ':'.
