Support executable prefixes on service files (@, -, :, +, !, !!)

On service files, the ExecStart= option supports extra prefixes (@, -, :, +, !, !!) on the executable path.^[1]

Currently (v1.4.4147) docker-systemctl-replacement shows an error if prefixes such as !! are used on a ExecStart= option. For example on Debian/Ubuntu when using apt-get to install some package dependencies, it triggers post update hooks, like calling systemd-resolved.service which produces this error:

ERROR:systemctl: systemd-resolved.service: Executable path is not absolute, ignoring: !!/lib/systemd/systemd-resolved

As a temporary workaround until prefixes are supported, an option in most cases is to remove the required symbols:

find /etc /usr/lib /lib -name '*.service' | xargs grep -l 'ExecStart=!!/' | xargs sed -i 's/!!//'

[1] https://www.freedesktop.org/software/systemd/man/systemd.service.html#ExecStart= ^{(version 245)}

[bytestream]

Seems like MySQL 8.0.29 is now using:

ExecStartPre=+/usr/share/mysql-8.0/mysql-systemd-start pre

This fails on master branch, but develop branch appears to work well.

[EzraBrooks]

Just because tools like systemd-resolved and systemd-timesyncd “shouldn’t” run in a container doesn’t mean there aren’t use cases. For instance, I use Docker to unit test Ansible roles that later run on full-fat systems. I can’t systemctl restart systemd-timesyncd with this script, which means it’s unusable in my NTP configuration test.