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From: cliff@demon.co.uk (Cliff Stanford)
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.unix.internals
Subject: Re: Would somebody please explain?
Summary: Undocumented Use of /bin/expr
Message-ID: <1991Apr22.230906.9239@demon.co.uk>
Date: 22 Apr 91 23:09:06 GMT
References: <1991Apr21.001702.5661@umbc3.umbc.edu> <1991Apr21.023416.5795@mp.cs.niu.edu>
Organization: Demon Systems Limited
Lines: 33

In article <1991Apr21.023416.5795@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes:
>In article <1991Apr21.001702.5661@umbc3.umbc.edu> rouben@math16.math.umbc.edu (Rouben Rostamian) writes:
>>The command:
>>    expr "Match" : "Ma"
>>returns 2, as it should, since the first two characters of "Match" and "Ma"
>>coincide.  Now, would somebody please explain why the command:
>>    expr "match" : "ma"
>>complains of a "syntax error"?
>
>  I just ran:  strings /bin/expr
>
>  From the output I would guess that 'match', 'index', 'substr' and 'length'
>are builin functions or operators for 'expr', although they are not documented
>in any man pages that I have seen.
>

	Well I'm blowed!  All those work although I've not seen any
documentation for any one of them. (SCO 3.2.2)

Input						Output
-----						------
expr match abcde abc				3
expr index abcde cd				3
expr length abcde				5
expr substr abcde 2 3				bcd

	Why doesn't anyone DOCUMENT unix?
		Cliff.
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