Re: acgeneral.m4 & unsupported case patterns

[Paul Eggert]

   From: Akim Demaille <[EMAIL PROTECTED]>
   Date: 23 May 2000 19:13:39 +0200

   |         if echo "$ac_package" | grep '[[^a-zA-Z0-9_]]' >/dev/null 2>&1; then
   |                 AC_MSG_ERROR([invalid package: $ac_package]);;
   |         fi

   is better, but that's where we come from.  The idea was to have the
   shell handle this, not a separate command.

expr is typically not built-in, but it's more portable than the
echo|grep solution, because it avoids the problem of 'echo'
implementations that do funny things with backslashes.  Scripts should
not use 'echo' to output strings that can contain backslashes.