From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Sun,  4 Oct 2009 06:11:18 +1100
From: Sam Watkins <sam@nipl.net>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Message-ID: <20091003191118.GD15021@nipl.net>
References: <20091003160327.GA15021@nipl.net>
	<20091003184617.14C075B2E@mail.bitblocks.com>
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Subject: Re: [9fans] mishandling empty lists - let's fix it
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On Sun, 04 Oct 2009 03:03:27 +1100 Sam Watkins <sam@nipl.net>  wrote:
> find -name '*.c' | xargs cat | cc -

On Sat, Oct 03, 2009 at 11:46:16AM -0700, Bakul Shah wrote:
> Your example doesn't hang (and if it does, your xargs is broken).

hm sorry, I meant:

  cat `find -name *.c` | cc -

> A common use of many tools is in a pipeline and having to type - every time
> can get annoying.

We could differentiate tools that work on stdin from tools that work on a list
of files.  Or each tool could default to one or the other.

If a tool normally works on a list of files (like cat), it can also use stdin:

  cat -

If a tool normally works on stdin (like sed), it can use a list of files:

  grep pattern : foo bar baz

By the way, grep is even more inconsistent than usual: it only adds the file:
prefix to matching lines when there are 2 or more files!

I don't see how this can be fixed in unix without breaking umpteen million
shell scripts.  But perhaps this could be corrected in plan 9 or inferno which
are still more experimental OSes; or we could keep it in mind for "plan 10".

Sam