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From: torek@elf.ee.lbl.gov (Chris Torek)
Newsgroups: comp.arch
Subject: Re: Globbing
Message-ID: <10803@dog.ee.lbl.gov>
Date: 11 Mar 91 09:35:54 GMT
References: <1991Feb18.152347.28521@dgbt.doc.ca> <474@bria> <19217@cbmvax.commodore.com> <5573:Feb2307:19:4491@kramden.acf.nyu.edu> <00085@meph.UUCP>
Reply-To: torek@elf.ee.lbl.gov (Chris Torek)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 80
X-Local-Date: Mon, 11 Mar 91 01:35:54 PST

(Sigh, I had hoped my observation that `what works in one system is not
necessarily appropriate/best for all' would end this, but...:)

In article <00085@meph.UUCP> gsarff@meph.UUCP writes:
>Sorry for the diatribe ...

I am not going to disagree with your general idea, but you really should
get the details right when you post something like this:

>Example 1:
>WMCS:
>    wscan *.c include*.h
>UNIX:
>    grep include\*.h *.c
>
>    Which is easier, or more intuitive?

Which is more powerful? :-)

Your grep command searches for `includ', followed by zero or more `e's
followed by any character except newline, followed by `h'.  You probably
meant

	grep 'include.*\.h' *.c

Grep-style regular expressions are more powerful than shell metacharacters,
at the expense of more complexity.  Note that, with back-references, grep
can be tricked into context-sensitive matches such as the one that pulled
the following words from the dictionary:

	% grep '^\(.*\)\1$' /usr/share/dict/web2
[actually, I cheated, the command I used was
 grep '^\(.*\)\1$' /usr/share/dict/web2 | rsh horse.ee.lbl.gov 'cat >tmp'
 since these boxes are running SunOS and do not have a web2.  I then deleted
 all but 27 words and ran these through `pr -3 -t -l9' to get a column sort.]

	atlatl			coco			furfur
	beriberi		couscous		gabgab
	bonbon			cuscus			gogo
	bulbul			dada			grigri
	cancan			dodo			grisgris
	caracara		dumdum			grugru
	chichi			enaena			guitguit
	chocho			eyey			gulgul
	chowchow		froufrou		juju

I will not argue grep's ease of use, but I would not give up much (if any)
of its power.

>Example 2:
>[directory with >24000 files] ... The best unix could do was print
>"Command line too long", because I had used * for file wildcarding.

This has been fixed in some Unixes, and will be fixed in others.

>Example 3:
>    ... I want to do the same scan on the entire disk,
>    so for the two OS's we get the following:
>
>wscan /*/*.c include*.h

(Does /*/ really mean `all directories' and not `the top level'?  If so,
how do you restrict the number of levels searched?)

>Unix:
>probably something like a shell loop or using find
>find / -name \* -exec grep include\*.h \{\} \;

Actually:

	find / -name '*.c' -exec grep 'include.*\.h' {} \;

or (given arbitrarily long argument lists):

	grep 'include.*\.h' `find / -name '*.c' -print`

Eschew backslash: quotes are your friends....
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab EE div (+1 415 486 5427)
Berkeley, CA		Domain:	torek@ee.lbl.gov