RX/TX stats on welcome banner (motd script): Refine RegEx to match real network interfaces only but ignore virtual interfaces by Docker & Co

[porg]

Environment:

Armbian on an Odroid-HC2 (Homecloud 2) which uses the odroid-xu4 firmware.

Reproduction:

1. After initial installation on the welcome banner "RX today:" always shows a nice value.
2. Install and run some docker containers. This changes /sys/class/net/ . AFAIK it adds so called "virtual network interfaces".
3. From then on the Armbian welcome screen displays like this:

• Error: Interface "veth•••••••" not found in database.
• Note: • redacted by me.

Analysis:

/etc/default/armbian-motd
…
PRIMARY_INTERFACE="$(ls -1 /sys/class/net/ | grep -v lo | egrep "enp|eth" | head -1)"
…

The current regular expression falsely matches veth••••••• (created by Docker).

$ ls -1 /sys/class/net/
br-••••••••••••
docker0
enx••••••••••••
lo
veth•••••••

I fixed it for myself by changing PRIMARY_INTERFACE to this:

"$(ls -1 /sys/class/net/ | grep -v lo | egrep "^en" | head -1)"

Fix Proposal:
A developer with proper knowhow of the network interface naming conventions changes the default regular expression / pipe for PRIMARY_INTERFACE so that it safely only matches a real hardware interface for all typical systems, also working fine when using docker or other software which may create virtual network interfaces or other stub like entries there.

Notes:

• This bug was already discussed in a forum thread in a "how to help yourself" manner.
• This here now is a formal bug report with the inquiry to please fix it.
  • I ran through the bug submission wizard at https://www.armbian.com/bugs/ which eventually led me here.

Edited January 4, 2023 by porg
Added note that this is a bug report

[atone]

Has been fixed last week: https://github.com/armbian/build/commit/24d2510c281ad20b6a26e7fa030e5f5c40bbd424

[porg]

Thanks for the fix!