IO::Socket::UNIX(3perl) Perl Programmers Reference Guide IO::Socket::UNIX(3perl)

IO::Socket::UNIX - Object interface for AF_UNIX domain sockets

use IO::Socket::UNIX;
my $SOCK_PATH = "$ENV{HOME}/unix-domain-socket-test.sock";
# Server:
my $server = IO::Socket::UNIX->new(
    Type => SOCK_STREAM(),
    Local => $SOCK_PATH,
    Listen => 1,
my $count = 1;
while (my $conn = $server->accept()) {
    $conn->print("Hello " . ($count++) . "\n");
# Client:
my $client = IO::Socket::UNIX->new(
    Type => SOCK_STREAM(),
    Peer => $SOCK_PATH,
# Now read and write from $client

"IO::Socket::UNIX" provides an object interface to creating and using sockets in the AF_UNIX domain. It is built upon the IO::Socket interface and inherits all the methods defined by IO::Socket.

Creates an "IO::Socket::UNIX" object, which is a reference to a newly created symbol (see the "Symbol" package). "new" optionally takes arguments, these arguments are in key-value pairs.

In addition to the key-value pairs accepted by IO::Socket, "IO::Socket::UNIX" provides.

Type        Type of socket (eg SOCK_STREAM or SOCK_DGRAM)
Local       Path to local fifo
Peer        Path to peer fifo
Listen      Queue size for listen

If the constructor is only passed a single argument, it is assumed to be a "Peer" specification.

If the "Listen" argument is given, but false, the queue size will be set to 5.

If the constructor fails it will return "undef" and set the $IO::Socket::errstr package variable to contain an error message.

$sock = IO::Socket::UNIX->new(...)
    or die "Cannot create socket - $IO::Socket::errstr\n";

For legacy reasons the error message is also set into the global $@ variable, and you may still find older code which looks here instead.

$sock = IO::Socket::UNIX->new(...)
    or die "Cannot create socket - $@\n";

Returns the pathname to the fifo at the local end
Returns the pathanme to the fifo at the peer end

Socket, IO::Socket

Graham Barr. Currently maintained by the Perl Porters. Please report all bugs at

Copyright (c) 1996-8 Graham Barr <>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

2022-12-12 perl v5.36.0