Current doc says: # Also, be aware that you can get the attributes of your network interface that # would be used to name the interface in the new scheme by doing the following # with this version of udev running: # # udevadm test-builtin net_id /sys/class/net/ifname 2> /dev/null # # for example, on my system, I can find that eth0's new name would be enp1s5. It's absolutely unclear what "ifname" at end of path isn't mean "ifname" but instead it's a placeholder for interface name like "eth0". It should be either replaced by "eth0" to show working example suitable for most users, or by something which looks like placeholder ("YOUR_INTERFACE_NAME" or "$ifname"), or comments around this example should explicitly state "ifname" should be replaced by interface name.
Thanks for reporting This is actually already fixed in 198-r1 by dropping of this file, and moving the example to the postinst message of the emerge As in, this will autoresolve with next stabilization round *** This bug has been marked as a duplicate of bug 453494 ***
