ubuntu packaging missing dependency on 'file'

[jcfp]

Installing the openvpn package for ubuntu bionic distributed via build.openvpn.net fails because its postinst script tries to use the file command, which may not be installed:

sudo apt-get install openvpn
[...]
Get:2 http://build.openvpn.net/debian/openvpn/stable bionic/main amd64 openvpn amd64 2.4.7-bionic0 [478 kB]
[...]
Selecting previously unselected package openvpn.
Preparing to unpack .../openvpn_2.4.7-bionic0_amd64.deb ...
Unpacking openvpn (2.4.7-bionic0) ...
Setting up openvpn (2.4.7-bionic0) ...
[...]
/var/lib/dpkg/info/openvpn.postinst: 63: /var/lib/dpkg/info/openvpn.postinst: file: not found
dpkg: error processing package openvpn (--configure):
 installed openvpn package post-installation script subprocess returned error exit status 1
Processing triggers for systemd (237-3ubuntu10.31) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Errors were encountered while processing:
 openvpn
E: Sub-process /usr/bin/dpkg returned an error code (1)

The 'file' utility is provided by the package of the same name. Since the priority of that package isn't set to either required or essential, a dependency is necessary to ensure its presence.

I didn't check other ubuntu versions or debian, but the problem is likely to affect those as well.

[tct]

Simple enough user work-around:

sudo apt update
sudo apt install file

This issue is two years old and is the only report of such that I can recall in ten years.

Please reopen if this occurs again.