You're suffering from multiple diseases.

First of all, try to give us something that should work cut-and-paste if there was no error. This helps us concentrate on the problem you have instead of working out a new example from the scratch, and helps you have more answers.

Then, IO::Select says:

       can_read ( [ TIMEOUT ] )
           Return an array of handles that are ready for reading.
           "TIMEOUT" is the maximum amount of time to wait before
           returning an empty list, in seconds, possibly frac-
           tional. If "TIMEOUT" is not given and any handles are
           registered then the call will block.
[download]

So it doesn't return the lines which wait to be read, but the handles that have data and that you can read from.

Last, but not least, you're maybe suffering from buffering. You don't provide much information about SOCKET/SOC, but note that if it buffers you could wait a long time before something is output. Unless it's really some socket, in which case you'd not.

Here's a working example, you'll be able to adapt it to your case easily. Note that the child sleeps 5 seconds, then checks for data in handles and reads from them.

#!/usr/bin/perl
use warnings;
use strict;
use IO::Select;

my $pid = open(PIP, "|-");
if ($pid < 0) {
    die "open(): $!";
}
elsif ($pid > 0) {
    print scalar localtime time, " - Parent: sending something to chil
+d\n";
    print PIP "Hi, son!\n";
    print scalar localtime time, " - Parent: waiting for child to fini
+sh\n";
    close PIP;
    print scalar localtime time, " - Parent: exiting\n";
}
else {
    my $selector = IO::Select->new(\*STDIN);
    print scalar localtime time, " - Child: just born!\n";
    sleep(60);
    my @handles = $selector->can_read(0);
    if (@handles) {
        print scalar localtime time, " - Child: there are " . scalar(@
+handles) . " handles ready for reading\n";
        # It can only be STDIN...
        my $line = <STDIN>;
        chomp($line);
        print scalar localtime time, " - Child: parent says: [$line]\n
+";
    }
    print scalar localtime time, " - Child: exiting\n";
    exit(0);
}

__END__
Sun May 22 15:43:48 2005 - Parent: sending something to child
Sun May 22 15:43:48 2005 - Child: just born!
Sun May 22 15:43:48 2005 - Parent: waiting for child to finish
Sun May 22 15:44:48 2005 - Child: there are 1 handles ready for readin
+g
Sun May 22 15:44:48 2005 - Child: exiting
Sun May 22 15:44:48 2005 - Parent: exiting
[download]

As a final note, always check the return status of open, it can fail!

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