create /etc/udev/rules.d/70-persistent-net.rules

Hello,

I hope that this is a right place fur udev questions.

My problem is that I need to create a file
/etc/udev/rules.d/70-persistent-net.rules on a PXE-Booted computer with an
NFS-Rootfilesystem. Unfortunately, that file ist not created automatically
at boot time, also "echo add > /sys/class/net/*/uevent" did not work,
though it did an another, disk-booted computer where I had deleted the
file before.

So, how can I create /etc/udev/rules.d/70-persistent-net.rules on a
netbooted computer, if possible without using tools like ifconfig, sed and
awk?

Regards
  Christoph