If your system actually has the constant, it will nowadays be in Socket.pm.

Query, set, unset: 

use Socket qw(IPPROTO_TCP TCP_NODELAY);

sub nagle(*;$) {
    my $fh = shift;
    if (!@_) {
        return unpack("I", getsockopt($fh, IPPROTO_TCP, TCP_NODELAY) |
+|
               croak "Could not get Nagle state: $!") ? 0 : 1;
    }
    if (shift) {
        setsockopt($fh, IPPROTO_TCP, TCP_NODELAY, 0) ||
            croak "Couldn't enable Nagle's algorithm: $!";
    } else {
        setsockopt($fh, IPPROTO_TCP, TCP_NODELAY,1) ||
            croak "Couldn't disable Nagle's algorithm: $!";
    }
}

[download]
(A lot of perl code floating on the internet incorrectly uses SOL_SOCKET as level, possibly because the cookbook gets it wrong).

This functionality should only be used if it makes sense though.

In reply to Re: Portably disabling Nagle's algorithm for TCP by thospel
in thread Portably disabling Nagle's algorithm for TCP by mowgli

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