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From: lars@yosemite.berkeley.edu (Lars E. Thon)
Newsgroups: comp.lang.perl
Subject: Double-ended pipes
Summary: Do they exist?
Keywords: pipe
Message-ID: <14054@pasteur.Berkeley.EDU>
Date: 11 Jun 91 20:03:21 GMT
References: <1991Jun10.180301.7925@NCoast.ORG>
Sender: news@pasteur.Berkeley.EDU
Reply-To: lars@yosemite.berkeley.edu.UUCP (Lars E. Thon)
Organization: UC Berkeley EECS Dept
Lines: 29

One feature that I have been missing from perl is having a double-ended
pipe. This could be useful f.ex. if you want to feed a lot of commands
to a csh and then analyze output and/or status from the commands. For a
simple (and contrived) example, consider the following:

#! /usr/local/gnu/bin/perl

doublepipe_open(CSH_IN, "| /bin/csh -f |", CSH_OUT); 

#Silly way of checking whether user ~blah exists
print CSH_IN "echo ~blah";
$pathname= <CSH_OUT>;
print CSH_IN "echo \$status";
$errcode= <CSH_OUT>;

if ($errcode) {
     print "User blah does not exist ...\n";
}
# END

I haven't seen a way to do this in perl, except for the obvious (but
unsatisfactory) method of using a temp file to store the csh output.

Any ideas about this?
--

----------------------------------------------------------------------------
Lars E. Thon,  lars@yukon.berkeley.edu, T. 415-642-9350
211-134 Cory Hall, UC Berkeley, CA 94720