Re: grep -E ? (Was: Compilation problem solved)

[Paul Eggert]

   Date: Tue, 29 Aug 2000 14:20:12 -0400 (EDT)
   From: Pavel Roskin <[EMAIL PROTECTED]>

   I haven't checked the older versions, but this behaviour of GNU grep is
   weird (it may or may not be a bug, dependent on the standard):

   $ echo foo |./grep -E ' *+'
   foo

It is not a bug.  GNU grep extends the semantics of regular
expressions so that 'x*+' is equivalent to '(x*)+'.  POSIX does not
require that grep -E reject ' *+'; it merely says that the results are
undefined.  So this behavior of GNU grep is correct even when
POSIXLY_CORRECT is set.