Subject: Re: Repalcement for grep(1)
To: Jamie Howard <>
From: Archie Cobbs <>
List: tech-userlevel
Date: 07/04/1999 18:09:02
Jamie Howard writes:
> Now, I am having a problem though.  I cannot figure out how to implement
> -w and -x.  For -x, I tried modifying the regular expression (foo) into
> ^(foo)$ before compiling, but that did not work.  I intended to do
> something similar with -w.  Anyway, I am probably missing the obvious, but
> does anyone have any ideas regarding how I should implement -w and -x?

From the re_format(7) man page:

       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-

Perhaps this will help with -w?


Archie Cobbs   *   Whistle Communications, Inc.  *