Generally

• Perl Cookbook
• IO::Socket::UNIX — this does NOT have sendmsg/recvmsg support
• a REAL WORKING EXAMPLE
  • more working examples

sendmesg/recvmsg

• Socket::MsgHdr
• File::FDPasser
• Socket::PassAccessRights — I confirmed this works A-okay for me, on normal Linux!
• pure Perl (!!)