setsockopt

setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL

Sets the socket option requested. Returns undef on error- Use integer constants provided by the Socket module for LEVEL and OPNAME. Values for LEVEL can also be obtained from getprotobyname. OPTVAL might either be a packed string or an integer. An integer OPTVAL is shorthand for pack("i", OPTVAL).

An example disabling Nagle's algorithm on a socket:

use Socket qw(IPPROTO_TCP TCP_NODELAY);
setsockopt($socket, IPPROTO_TCP, TCP_NODELAY, 1);

Portability issues: setsockopt in perlport.