systemd - Why doesn't pstree command show init in Ubuntu 16.04 LTS? - Ask Ubuntu

i trying examine output pstree command. reason starts called systemd opposed being init. have checked see process id's of both init , systemd using ps aux command , init has pid of 1, while systemd has other pid. why isn't init being shown in pstree's output? there option need give?

also did read systemd vs init controversy, ubuntu 16.04 lts still uses init start right?

update why different pids?

it turns out different pids thought part of ignorance. init had pid 1, whereas systemd wasn't thing talking about. instead when ran ps aux|grep systemd, found pids /lib/systemd/systemd-*, * means characters. talking not systemd, other processes extensions(is correct word?) of systemd guess.

some of examples * follows

/lib/systemd/systemd-journald /lib/systemd/systemd-udevd /lib/systemd/systemd-timesyncd 

since 15.04, init on ubuntu systemd. it possible use upstart, default systemd. example, /sbin/init link /lib/systemd/systemd. /sbin/{shutdown,reboot,telinit,halt,runlevel,poweroff} links /sbin/systemctl. in 16.04, upstart used session init, might see upstart parent process or ancestor process in graphical login (though it seems have changed in 16.10).

the other processes see systemd components; they're developed , distributed along systemd many not essential running systemd init. many components can replaced or disabled. quote the systemd homepage:

systemd suite of basic building blocks linux system. provides system , service manager runs pid 1 , starts rest of system. ... other parts include logging daemon, utilities control basic system configuration hostname, date, locale, maintain list of logged-in users , running containers , virtual machines, system accounts, runtime directories , settings, , daemons manage simple network configuration, network time synchronization, log forwarding, , name resolution.

and this blog post 1 of creators of systemd (lennart poettering):

29. myth: systemd doesn't allow replace components.

    not true, can turn off , replace pretty part of systemd, few exceptions. , exceptions (such journald) allow run alternative side side it, while cooperating nicely it.