Question

I need to write a daemon that supposed to have one TCP socket and one named pipe. Usually if I need to implement a multi IO server with “pure” sockets, the select based multi-IO model is always the one I will choose. so does anyone of you have ever used named pipe in select or you
can just tell me it is impossible. thanks in advance.

Answer 1

In a word, yes:

#!/usr/bin/perl

use strict;
use warnings;

use POSIX qw/mkfifo/;
use IO::Select;
use IO::Handle;

my $filename = "/tmp/pipe.$$";

mkfifo $filename, 0700
    or die "could not create pipe $filename: $!";

die "could not fork\n" unless defined(my $pid = fork);
unless ($pid) {
    open my $fh, ">", $filename
        or die "could not open $filename\n";

    my $i = 1;
    for (1 .. 10) {
        sleep 1;
        print $fh $i++, "\n";
        $fh->flush;
    }
    exit;
}

my $s = IO::Select->new;

open my $fh, "<", "$filename"
    or die "could not open $filename\n";

$s->add($fh);

OUTER: while (1) {
    print localtime() . "\n";
    my @files = $s->can_read(.25);
    if (@files) {
        for my $fh (@files) {
                    my $line = <$fh>;
            print "from pipe: $line";
            last OUTER if $line == 10;
        }
    }
}