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From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: Breaking a pipe
Message-ID: <1990Apr11.084610.16131@iwarp.intel.com>
Date: 11 Apr 90 08:46:10 GMT
References: <BLARSEN.90Apr11084353@spider.uio.no>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
Distribution: comp
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 37
In-Reply-To: blarsen@spider.uio.no (Bjorn Larsen)

In article <BLARSEN.90Apr11084353@spider.uio.no>, blarsen@spider (Bjorn Larsen) writes:
| I have a Perl script that reads from a filehandle opened
| with
|              open(F, "tail -f somefile |");
| 
| and at some point I want to close the filehandle and reopen it.
| 
| However, according to the manpage,
| 
|                              Also, closing a pipe will wait for
|              the process executing on the pipe to complete, in
|              case you want to look at the output of the pipe
|              afterwards.                                         
| 
| So, naturally my script goes blissfully to sleep waiting
| for the pipe to complete.
| 
| How do I break a pipe if I *don't* want to look at the output of
| the pipe afterwards?

Opening a pipe returns the process ID (PID) of the spawned shell, so
hang on to the result of the open, as in:

	$Fpid = open(F,"tail -f somefile |");

and later when you want to make it go away, say:

	kill 9, $Fpid; close(F);

The kill makes the process die, so the close returns immediately.

eval q(eval q-eval q:print"Just another Perl hacker,"  :-)
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
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