I have 2 different embedded devices...an old one running TI arago Linux and a Xilinx device (petalinux).

On both I see the same outcome when adding dns-nameservers to /etc/network/interfaces and reconfiguring the network with /etc/init.d/networking restart or rebooting the device:
The /etc/resolv.conf file always stays empty.

No dhclient, resolvconf package, network-manager daemon or mdns are present in the system.

Here the /etc/network/interfaces:

# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static

and resolv.conf:

[root@linux:~] ls -l /etc/resolv.conf 
lrwxrwxrwx    1 root     root           20 Feb  3 18:17 /etc/resolv.conf -> /var/run/resolv.conf
[root@linux:~] ls -l /var/run/resolv.conf
-rw-r--r--    1 root     root            0 Feb  3 18:17 /var/run/resolv.conf

While executing /etc/init.d/networking restart, both devices call basically ifdown -a and then ifup -a, being both ifup and ifdown busybox utilities in this case.

In case mentioning the immutable file attributes solution: I don't want to generate manually the resolv.conf file and change the file attributes to make it immutable (chattr +i), because it seems completely against how the system was designed. Why is then resolv.conf stored in volatile memory (generated by populate-volatile.sh) in the first place, if it should be permanent?

Thanks for any hints!

Update: found the solution, but will leave the question, for the sake of somebody searching for it.


Create a script in /etc/network/if-up.d/dns with this content (in this example only eth0 is taken into account):

if [ "$IFACE" = "eth0" ];then
R="${R}nameserver $NS
echo "$R" > /etc/resolv.conf

Make it executable with chmod +x /etc/network/if-up.d/dns.

Everytime you reboot the device or restart the networking services, resolv.conf will be recreated. Works like a charm!

PS: If you use another directive/naming than dns-nameservers in /etc/network/interfaces...for example my-dns, then replace $IF_DNS_NAMESERVERS with $IF_MY_DNS. Although it's cool to know, I would rather stick to conventions and use dns-nameservers.

  • I'm not convinced this is a good solution. Do you have mdns running on these systems? – tripleee Feb 4 at 10:51
  • @tripleee No, mdns is not installed in the system. Can you share a more extended answer on why you are not convinced this is a good solution or do you have a better one? Thanks. – marc Feb 4 at 10:52

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