#!/usr/bin/perl
use strict;
use warnings;
use Socket;
require 'sys/ioctl.ph';

print get_interface_address('eth0');

sub get_interface_address
{
	my ($iface) = @_;
	my $socket;
	socket($socket, PF_INET, SOCK_STREAM, (getprotobyname('tcp'))[2]) || die "unable to create a socket: $!\n";
	my $buf = pack('a256', $iface);
	if (ioctl($socket, SIOCGIFADDR(), $buf) && (my @address = unpack('x20 C4', $buf)))
	{
		return join('.', @address);
	}
	return undef;
}

This method doesn't rely on parsing 'ifconfig' tool output, and should work in any Linux distribution, but also could work in other POSIX environments.
The function returns a string with IPv4 address or 'undef' if it's not possible.

the most reliable and correct method to get network interface address in Linux using Perl

Perl