[San-Diego-pm] Module idea for input/output multiplexing

[Menolly]

So...a cross-platform tee, basically?

On Mon, 11 Dec 2006, Emile Aben wrote:

> Hi,
>
> Module idea from discussion at the meeting tonight:
> A module that hooks up stdout from one process with the stdin of
> several other processes,
> or maybe more generic: Something that reads from a filehandle and
> writes that output to
> several other filehandles.
>
> Simple example of use:
> reading a gzipped file from disk, and calculating the md5 (using md5,
> md5sum or 'openssl md5' command, depending on your OS) and linecount
> (wc -l) **
>
> I've looked into IPC::Run a bit, and IPC::Run might be able to do
> something like this, but
> the best I've been able to come up with this far doesn't work:
> ----
> #!/usr/bin/env perl
> use Carp;
> use strict;
> use warnings;
> use IPC::Run qw(run);
>
> my $cat_cmd = ['cat'];
> my $md5_cmd = ['/usr/bin/openssl','md5'];
> my $wc_cmd = ['wc','-l'];
>
> my $md5_out = undef;
> my $wc_out = undef;
>
> run($cat_cmd,'<',"$0", '>&3', '>&4',
>  '3>pipe', $md5_cmd, '>', \$md5_out,
>  '4>pipe', $wc_cmd,   '>', \$wc_out);
>
> print "linecount: $wc_out\n";
> ---
> which produces errors:
> Not a GLOB reference at /usr/lib/perl5/site_perl/5.8.3/IPC/Run/IO.pm line 329.
> Not a GLOB reference at /usr/lib/perl5/site_perl/5.8.3/IPC/Run/IO.pm line 329.
>
> or under perl -d:
>        IPC::Run::start('ARRAY(0x98ee6a8)','<','./ipcrun.pl','>&3','>&4','3>pipe','ARRAY(0x98ee714)','>','SCALAR(0x97efce0)',...)
> called at /usr/lib/perl5/site_perl/5.8.3/IPC/Run.pm line 1434
>     IPC::Run::run('ARRAY(0x98ee6a8)','<','./ipcrun.pl','>&3','>&4','3>pipe','ARRAY(0x98ee714)','>','SCALAR(0x97efce0)',...)
> called at ./ipcrun.pl line 14
>
> that's enough for me tonight.
>
> Emile
>
>
> ** both calculating md5 and linecount can be done in perl as well of
> course, but that's not the point here
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-- 
menolly at mib.org                    http://www.livejournal.com/~nolly/

On that day, many will say to me, "Lord, Lord, did we not prophesy in
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in your name?" And then will I declare to them, "I never knew you;
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