The previous testing was misleading. First of all, /run is a temporary folder: > 9.1.4. /run and /run/lock > The directory /run is cleared at boot, normally by being a mount point for a > temporary file system - https://www.debian.org/doc/debian-policy/ch-opersys.html#run-and-run-lock
we would only have /run/systemd/system if we booted with systemd. However, if we were actively using systemd and tried to remove the systemd package we would hit this code in prerm: > $ cat /var/lib/dpkg/info/systemd.prerm > #! /bin/sh > > set -e > > # > # Prevent systemd from being removed if it's the active init. That > # will not work. > # > > if [ "$1" = "remove" ] && [ -d /run/systemd/system ]; then > echo "systemd is the active init system, please switch to another before > removing systemd." > exit 1 > fi >(...) Thus the check of /run/systemd/system used by dh_systemd_start is sufficient to ensure the init system to be systemd, in which case there will be a systemctl. A system with /run/systemd/system but no systemctl should probably be considered broken. Specially given that the check for /run/systemd/system existence appears in multiple places and packages. Moving systemd dependency to Recommends should be perfectly safe.
