Read your update. If all what you want is to create socket once, and use it repeatedly, there is certainly no need for you to convert to IO::Socket. Just like you can use variables when you open files, you can do the same thing towards socket, and thus it follows the usual scope rules. For example: (code is tested)

use Socket;

use strict;
use warnings;

my $yahoo;
socket($yahoo, PF_INET, SOCK_STREAM, getprotobyname('tcp')) || die "so
+cket: $!";
connect($yahoo, sockaddr_in(80, inet_aton("www.yahoo.com"))) || die "c
+onnect: $!";
syswrite($yahoo, "GET / HTTP/1.1\r\nHost: www.yahoo.com\r\n\r\n");
read_one_line($yahoo);
read_one_line($yahoo);

sub read_one_line {
    my $sock = shift;
    my $line = <$sock>;
    print $line;
}
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This also works, but I like the first solution better:

use Socket;

use strict;
use warnings;

socket(YAHOO, PF_INET, SOCK_STREAM, getprotobyname('tcp')) || die "soc
+ket: $!";
connect(YAHOO, sockaddr_in(80, inet_aton("www.yahoo.com"))) || die "co
+nnect: $!";
syswrite(YAHOO, "GET / HTTP/1.1\r\nHost: www.yahoo.com\r\n\r\n");
read_one_line(*YAHOO);
read_one_line(*YAHOO);

sub read_one_line {
    my $sock = shift;
    my $line = <$sock>;
    print $line;
}
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