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From: scs@adam.pika.mit.edu (Steve Summit)
Newsgroups: comp.unix.wizards
Subject: Re: filename substitution question
Message-ID: <10100@bloom-beacon.MIT.EDU>
Date: 25 Mar 89 05:37:23 GMT
References: <1627@ncar.ucar.edu>
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Reply-To: scs@adam.pika.mit.edu (Steve Summit)
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In article <1627@ncar.ucar.edu> rob@scdpyr.ucar.edu (Robert Montgomery) writes:
>Often it would be simpler to specify what I *don't* want in filename
>substitution than what I do.  For example, I would like to do something
>similar the following:
>	ls {NOTfrog}.c
>and have it produce:
>	bird.c		fish.c

A nice solution which I have not seen mentioned yet is the "pick"
program, described in Kernighan and Pike's book, The Unix
Programming Environment.  You always invoke pick inside of
backquotes, viz.:

	command `pick *.c`

and you get to answer yes or no for each filename.  It'd be silly
for the ls example (but then again, so would anything; the
problem comes up more typically when the command in question is
going to modify the files somehow).

pick essentially allows you to add an "inquire" facility to any
program; for instance,

	rm -i *

is equivalent to

	rm `pick *`

The only problem with pick is that people who use the MH mail
system already have another meaning for the command.

For simply listing files, I find that postprocessing (rather than
preselecting) is usually more convenient.  For example, a
frequent idiom of mine is

	ls -lt | grep -v '\.o$'

to see what source files I've changed lately.

If you can neither find a copy of Kernighan and Pike (as I
recall, it included source code) nor write pick yourself (the
only tricky part is using /dev/tty) I can send you my
implementation. (I ought to just include it here; it's under 50
lines long.)

                                            Steve Summit
                                            scs@adam.pika.mit.edu