Dear Maintainer,

When there are no interface files in /etc/network/interfaces.d/* ifupdown returns warning to NetworkManager.

NetworkManager[932]: <warn>  [1622551341.0762] ifupdown: interfaces file /etc/network/interfaces.d/* doesn't exist

My connections are managed by NetworkManager and I have none files in in
there.

Workaround is to comment out sources line in interfaces

#source /etc/network/interfaces.d/*

Bug doesn't cause any issues in functionality as of I know of.
--- /etc/network/interfaces.d/*:
cat: '/etc/network/interfaces.d/*': No such file or directory

--- up and down scripts installed:
/etc/network/if-down.d:
total 4
-rwxr-xr-x 1 root root 1015 Feb  6 16:05 avahi-autoipd
lrwxrwxrwx 1 root root   32 Feb 25 22:19 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-post-down.d:
total 4
-rwxr-xr-x 1 root root 1409 Mar  7  2020 wireless-tools
lrwxrwxrwx 1 root root   32 Feb 25 22:19 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-pre-up.d:
total 12
-rwxr-xr-x 1 root root  344 Jun 30  2016 ethtool
-rwxr-xr-x 1 root root 4191 Mar  7  2020 wireless-tools
lrwxrwxrwx 1 root root   32 Feb 25 22:19 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-up.d:
total 8
-rwxr-xr-x 1 root root  923 Feb  6 16:05 avahi-autoipd
-rwxr-xr-x 1 root root 1685 Jun 30  2016 ethtool
lrwxrwxrwx 1 root root   32 Feb 25 22:19 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

Dear Maintainer,


Same warning with last version (0.8.36+nmu1).


"man interfaces" say:
By  default,  on  a  freshly  installed  Debian system, the interfaces file includes a line to source files in the
/etc/network/interfaces.d directory.


I prefer a quick and easy solution like creating any file within /etc/network/interfaces.d/,
 either empty (checked) or with any comments (checked too):

sudo touch /etc/network/interfaces.d/anything
or
echo "# ... like 'This page intentionally left blank' ... " | sudo tee /etc/network/interfaces.d/anything.00000000


This solves this bug without modify the default file /etc/network/interfaces (1).



One question: checking the .deb file, (1) is not included, and if I search for 'apt-file search /etc/network/interfaces',
 this package 'ifupdown' does not appear. Should it be so?


Thank you very much.

Dear Maintainer,

No warnings with the latest version 0.8.37 and no files in /etc/network/interfaces.d/:

 NetworkManager[829]: <info>  [1650793569.4283] monitoring ifupdown state file '/run/network/ifstate'.
 NetworkManager[829]: <info>  [1650793573.6997] settings: Loaded settings plugin: ifupdown ("/usr/lib/x86_64-linux-gnu/NetworkManager/1.36.4/libnm-settings-plugin-ifupdown.so")
 NetworkManager[829]: <info>  [1650793573.6998] ifupdown: management mode: unmanaged
 NetworkManager[829]: <info>  [1650793573.6998] ifupdown:       interface-parser: parsing file /etc/network/interfaces
 NetworkManager[829]: <info>  [1650793573.6998] ifupdown:       interface-parser: source line includes interfaces file(s) /etc/network/interfaces.d/*
 NetworkManager[829]: <info>  [1650793573.6999] ifupdown: interfaces file /etc/network/interfaces.d/* doesn't exist
 NetworkManager[829]: <info>  [1650793573.6999] ifupdown:       interface-parser: finished parsing file /etc/network/interfaces

I think it could be marked as resolved.

Thank you very much.
--- /etc/network/interfaces.d/*:
cat: '/etc/network/interfaces.d/*': No such file or directory

--- up and down scripts installed:
/etc/network/if-down.d:
total 4
-rwxr-xr-x 1 root root 1677 2019-03-30 15:32:49 clamav-freshclam-ifupdown
lrwxrwxrwx 1 root root   32 2022-04-09 09:28:35 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-post-down.d:
total 0
lrwxrwxrwx 1 root root 28 2018-06-17 11:28:32 macchanger -> ../../macchanger/ifupdown.sh
lrwxrwxrwx 1 root root 32 2022-04-09 09:28:35 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-pre-up.d:
total 4
-rwxr-xr-x 1 root root 344 2016-06-30 16:53:02 ethtool
lrwxrwxrwx 1 root root  28 2018-06-17 11:28:32 macchanger -> ../../macchanger/ifupdown.sh
lrwxrwxrwx 1 root root  32 2022-04-09 09:28:35 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-up.d:
total 8
-rwxr-xr-x 1 root root 1677 2019-03-30 15:32:49 clamav-freshclam-ifupdown
-rwxr-xr-x 1 root root 1685 2016-06-30 16:53:02 ethtool
lrwxrwxrwx 1 root root   32 2022-04-09 09:28:35 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh