Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84 exptools; site whuxl.UUCP
Path: utzoo!watmath!clyde!cbosgd!ihnp4!mhuxn!mhuxr!mhuxt!houxm!whuxl!mike
From: mike@whuxl.UUCP (BALDWIN)
Newsgroups: net.unix
Subject: Re: KSH substring function (is it on your system?)
Message-ID: <813@whuxl.UUCP>
Date: Wed, 13-Nov-85 23:49:07 EST
Article-I.D.: whuxl.813
Posted: Wed Nov 13 23:49:07 1985
Date-Received: Fri, 15-Nov-85 04:47:29 EST
References: <121@rruxc.UUCP> <9@pixutl.UUCP>
Organization: AT&T Bell Laboratories, Whippany
Lines: 28

> As long as we're talking about 'substring', 'expr' has a 'substr' option
> that used to be documented in V6.
> 
> It goes:
> 	expr substr string n m
> 
> 	where n is the first character of the sub-string and m the length.
> 
> 	so:		expr substr abcdefgh 2 4
> 	gives:		bcde
> 
> 'expr' also has 'match', 'lentgh', and 'index' options that are not
> documented any longer. Anyone knows why?

The ":" operator of expr now handles all of these cases (I've never
heard of "index"; what does it do?):

-- old --				-- new --
expr match string regexp		expr string : regexp
expr length string			expr string : '.*'
expr substr string off len		expr string : '.\{off-1\}\(.\{len\}\)'

Of course, you have to make sure that "string" isn't a valid expr
operator.  Putting an ordinary char like _ at the beginning of both
the string and the regexp will fix that.
-- 
						Michael Baldwin
						{at&t}!whuxl!mike