We have apticron on our servers that will send emails when there are pending package upgrades. The emails have a subject like this:
30 Ubuntu package update(s) for name-of-server
After the major upgrade from Ubuntu 16 to Ubuntu 18 the server name is not showing anymore in the email subject:
30 Ubuntu package update(s) for
The apticron.conf didn't change during the upgrade. Only EMAIL is set, everything else is commented out. Also the part for SYSTEM:
# Set SYSTEM if you would like apticron to use something other than the output
# of "hostname -f" for the system name in the mails it generates. This option
# overrides the ALL_FQDNS above.
#
# SYSTEM="foobar.example.com"
hostname -f is working fine and outputs the system name as excepted.
Does anybody have an idea how this could be fixed?