On Tue, Mar 22, 2022 at 11:21:30AM +0300, Reco wrote: > It makes little sense to have two or more NTP clients installed on the > same host. Thus installing one should uninstall others.
In jessie, stretch and buster, systemd-timesyncd was not a separate package. The systemd-timesyncd program was part of the systemd package, which was of course installed by default. The unit file was written so that if any of the *programs* from any of the other Debian NTP packages (ntp, chrony, openntpd) exists, then systemd-timesyncd would not start. If you installed ntp (for example), then ntpd would run, but systemd-timesyncd would not. (I'm looking at a buster box right now, and /lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf contains the relevant directives.) In bullseye, this configuration was changed. systemd-timesyncd is now a separate package, and is still installed by default (assuming one does not change the init system). If ntp or chrony or openntpd is installed, then systemd-timesyncd is removed, as they all have this: unicorn:~$ apt-cache show systemd-timesyncd | grep Prov Provides: time-daemon unicorn:~$ apt-cache show ntp | grep Prov Provides: time-daemon [...] So, while it may "make little sense" to do it the older way, apparently the Debian developers found it sensible for three releases. The current method is definitely a change, and if the OP is running various scripts that relied on the old method, those scripts may need to change.
