Get the name of a network interface

This recipe gets the name of the first real network interface. I use it to add if_ and if_errcoll_ graphs to Munin.

#
# if_name.rb
#
# gets the name of the first real ethernet interface
#

Facter.add(:if_name) do
    confine :kernel => :linux
    setcode do
        if_name = nil
        output = %x{/sbin/ifconfig}
        output.each_line do |line|
            if line =~ /(^\S+)\s+Link encap:Ethernet/
                tmp = $1
                unless tmp =~ /^lo\d+/
                    if_name = tmp
                    break
                end
            end
        end
        if_name
    end
end

Facter.add(:if_name) do
    confine :kernel => %w{FreeBSD NetBSD OpenBSD}
    setcode do
        if_name = nil
        output = %x{/sbin/ifconfig}
        output.each_line do |line|
            if line =~ /(\S+):\sflags.*<.*UP.*>/
                tmp = $1
                unless tmp =~ /^lo\d+/
                    if_name = tmp
                    break
                end
            end
        end
        if_name
    end
end