Subject: Re: Repalcement for grep(1)
To: Archie Cobbs <>
From: Jamie Howard <>
List: tech-userlevel
Date: 07/04/1999 21:32:22
On Sun, 4 Jul 1999, Archie Cobbs wrote:

>        There are two special cases- of bracket  expressions:  the
>        bracket expressions `[[:<:]]' and `[[:>:]]' match the null
>        string at the beginning and end of a word respectively.  A
>        word  is defined as a sequence of word characters which is
>        neither preceded nor followed by word characters.  A  word
>        character  is  an alnum character (as defined by ctype(3))
>        or an underscore.  This is an extension,  compatible  with
>        but not specified by POSIX 1003.2, and should be used with
>        caution in software intended to be portable to other  sys-
>        tems.
> Perhaps this will help with -w?

Yes, I received a patch from Simon Burge which implements this.  It also
beats using [^A-Za-z] and [A-Za-z$] as I was and GNU grep does.   I am
still having trouble with -x though.  It turns out that even if I specify
a commandline with a pattern of the form "^pattern$", it fails.  If I
specify "^pattern" it works.  If I specify "pattern$" it does not.  I have
yet to find a case where my version will sucessfully match when a $ is at
the end.  Has anyone encountered anything like this before?