The way the newer versions solve this is to have a native systemd service and in there there is:
Conflicts=systemd-timesyncd.service openntpd.service That ensures only one of these can be started. Xenial has no systemd service at all, it has sysV and uses the systemd generator. So there is no "just add the line" fix available. Xenial as-is $ timedatectl status Network time on: yes NTP synchronized: yes RTC in local TZ: no systemctl status systemd-timesyncd.service ● systemd-timesyncd.service - Network Time Synchronization Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled) Drop-In: /lib/systemd/system/systemd-timesyncd.service.d └─disable-with-time-daemon.conf Active: active (running) since Wed 2018-03-21 16:00:19 UTC; 1min 30s ago This isn't even fully protected if you install ntp (not chrony) as it was the ntp server back in Xenial. (Right after install it still runs). What stops it there for NTPd is that this uses a config dir which pulls in: /lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf So any further starts will be blocked: # don't run timesyncd if we have another NTP daemon installed ConditionFileIsExecutable=!/usr/sbin/ntpd ConditionFileIsExecutable=!/usr/sbin/openntpd ConditionFileIsExecutable=!/usr/sbin/chronyd ConditionFileIsExecutable=!/usr/sbin/VBoxService You see that if you check systemd-timesyncd.service: $ systemctl status systemd-timesyncd.service ● systemd-timesyncd.service - Network Time Synchronization Loaded: loaded (/lib/systemd/system/systemd-timesyncd.service; enabled; vendor preset: enabled) Drop-In: /lib/systemd/system/systemd-timesyncd.service.d └─disable-with-time-daemon.conf Active: inactive (dead) Condition: start condition failed at Wed 2018-03-21 16:06:42 UTC; 44s ago ConditionFileIsExecutable=!/usr/sbin/ntpd was not met After installing Chrony this is the same: Condition: start condition failed at Wed 2018-03-21 16:11:37 UTC; 1s ago ConditionFileIsExecutable=!/usr/sbin/chronyd was not met That is good (no special issue to chrony) and bad (actually all timeservers "collide" right after install). A reboot or restart will pick that up. OTOH it is discouraged to start/stop/restart other packages services form a postinst - as the first thought would be to do refresh for that condition after installing any of these. Given that there was not a single complaint about it in 2 years of Xenial other than us now looking for it in detail I'd rate it low, but it is a valid issue. ** Also affects: ntp (Ubuntu) Importance: Undecided Status: New ** Also affects: openntpd (Ubuntu) Importance: Undecided Status: New ** Changed in: ntp (Ubuntu Xenial) Status: New => Confirmed ** Changed in: ntp (Ubuntu Xenial) Importance: Undecided => Low ** Changed in: chrony (Ubuntu Bionic) Importance: Undecided => Low -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1756987 Title: chrony install does not stop systemd-timesyncd Status in chrony package in Ubuntu: Fix Released Status in ntp package in Ubuntu: New Status in openntpd package in Ubuntu: New Status in chrony source package in Xenial: New Status in ntp source package in Xenial: Confirmed Status in openntpd source package in Xenial: New Status in chrony source package in Artful: New Status in ntp source package in Artful: New Status in openntpd source package in Artful: New Status in chrony source package in Bionic: Fix Released Status in ntp source package in Bionic: New Status in openntpd source package in Bionic: New Bug description: 1. root@ubuntu:~# lsb_release -rd Description: Ubuntu 16.04.4 LTS Release: 16.04 root@ubuntu:~# uname -a Linux ubuntu 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux 2. root@ubuntu:~# apt-cache policy systemd systemd: Installed: 229-4ubuntu21.1 Candidate: 229-4ubuntu21.1 Version table: *** 229-4ubuntu21.1 500 500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages 500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages 100 /var/lib/dpkg/status 229-4ubuntu4 500 500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages root@ubuntu:~# apt-cache policy chrony chrony: Installed: 2.1.1-1 Candidate: 2.1.1-1 Version table: *** 2.1.1-1 500 500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages 100 /var/lib/dpkg/status 3. installing chrony should stop systemd-timesyncd so they both don't try to adjust time 4. after chrony is installed both systemd-timesyncd and chronyd are running. root@ubuntu:~# ps aux | egrep "(chrony|timesync)" systemd+ 1086 0.0 0.2 100324 2368 ? Ssl 19:34 0:00 /lib/systemd/systemd-timesyncd _chrony 2770 0.0 0.2 105780 2920 ? S 19:38 0:00 /usr/sbin/chronyd root 3077 0.0 0.0 12944 924 pts/0 S+ 19:52 0:00 grep -E --color=auto (chrony|timesync) Note, on bionic the chrony package successfully stops systemd-timesyncd and only chronyd remains running after install. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: chrony 2.1.1-1 ProcVersionSignature: Ubuntu 4.4.0-116.140-generic 4.4.98 Uname: Linux 4.4.0-116-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.15 Architecture: amd64 Date: Mon Mar 19 19:51:06 2018 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: chrony UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/chrony/+bug/1756987/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : group.of.nepali.translators@lists.launchpad.net Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp