net-traffic exits unexpectedly

[winks]

Hello,
on 20.04 with a default route through a VPN the IF detection in https://github.com/regolith-linux/regolith-i3xrocks-config/blob/master/scripts/net-traffic#L19 seems to fail:

$ ip route show default                                      
default dev vpn0 proto static scope link metric 50 
default via 192.168.178.1 dev enxb07b2540cf7b proto dhcp metric 10

$ ip route show default | awk '!/(ppp|tun|tap)/ { print $5 }'
static
enxb07b2540cf7b

I've not deeply looked into this, but I think this should work:

--- /tmp/net-traffic    2022-01-17 09:16:22.685425820 +0100
+++ /usr/share/i3xrocks/net-traffic     2022-01-17 09:16:08.865327514 +0100
@@ -16,7 +16,7 @@
 NUMFMT="numfmt --to iec --format %f --padding 5"
 
 # determine the net interface name
-IF="${BLOCK_INSTANCE:-$(ip route show default | awk '!/(ppp|tun|tap)/ { print $5 }')}"
+IF="${BLOCK_INSTANCE:-$(ip route show default | awk '!/(ppp|tun|tap|vpn)/ { print $5 }')}"

Now the problem is that I think this is not a good solution. (Thus this is an issue and not a PR)

For example with wireguard the interface name could be completely custom, cf. https://www.wireguard.com/netns/ - although I've seen people use the wg0 from the examples, but wg-quick again derives it from the config.

In any case, I think there should be a | head -n 1 at the end, because a 0 as an output value might be better than a spammy log file like I have it:

Jan 17 08:39:05 ws6 regolith.desktop[2724]: <3>[net-traffic] Command '/usr/share/i3xrocks/$BLOCK_NAME' exited unexpecte>
Jan 17 08:39:15 ws6 regolith.desktop[2709]: <3>[net-traffic] Command '/usr/share/i3xrocks/$BLOCK_NAME' exited unexpecte>
Jan 17 08:39:15 ws6 regolith.desktop[2695]: <3>[net-traffic] Command '/usr/share/i3xrocks/$BLOCK_NAME' exited unexpecte>
...

[winks]

Maybe something like this would be a little safer:

awk '$2 == 00000000 && $1 ~ /^(wl|en|eth)/ { print $1 }' < /proc/net/route 

For reference: https://www.freedesktop.org/software/systemd/man/systemd.net-naming-scheme.html - Table 1, add other prefixes if needed.

edit: Also there are still distros without the net naming scheme, so maybe better to add eth and whatever the old wifi default was.. wlan0 or wifi0?

[JoeOsborn]

I bumped into this today and I like @winks 's solution, much better than the hack I used of adding vpn0 to the awk pattern.

[kgilmer]

Would someone be able to provide a PR that verifies the fix? @winks @JoeOsborn