29

I'm on Ubuntu 10.10, and I've just joined the Linux world coming from OS X. I'm learning about runlevels and the rc directory in /etc/, and everywhere (manuals, tutorials, etc) I'm reading about inittab. But I can't find it in my Ubuntu installation. Why? Does Ubuntu follow the runlevel model? How are rc and levels loaded without inittab?

24

If you do man inittab in your terminal, all shall be revealed:

   The  /etc/inittab  file was the configuration file used by the original
   System V init(8) daemon.

   The Upstart init(8) daemon does not use this file,  and  instead  reads
   its  configuration  from  files  in  /etc/init.   See  init(5) for more
   details.
  • Worth to note, in /usr/share/doc/upstart/README.Debian.gz there is some other info. – enzotib Apr 10 '11 at 6:17
  • but upstart keep using /etc/rc.* ? – nkint Apr 10 '11 at 10:33
  • @nkint: upstart keep using /etc/rc.* for packages not aware of upstart – enzotib Apr 10 '11 at 12:23
  • 5
    No manual entry for inittab on 16.04... (he says, years later) – galois Jun 23 '17 at 14:41
  • 1
    Aye, apropos inittab will give nothing, in 16.04 the closest bit of info in the OS itself left seems to be in man runlevel. – Jeroen Aug 2 '17 at 20:12
11

Back in the days the "System-V" init service was used in Ubuntu, and it used the /etc/inittab file.

Some time ago (around 2006) the "Upstart" init service replaced SysV. During these days you could follow the top answer and use man inittab to get info on this change.

At the time of writing (e.g. for Ubuntu 16.04) the "systemd" boot process is in use and there is no reference left to "inittab" (e.g. if you do apropos inittab you'll probably not find anything). Instead you could do man runlevel to get similar information.

Bottom line: the /etc/inittab file is nowhere, likely because you use a newer version for Ubuntu that has a different init service, e.g. systemd.

10

While searching this in various forum, I got to know that /etc/inittab is not anymore used in debian distro.

It uses /etc/init/rc-sysinit.conf

  • 1
    not present in Ubuntu 18.04 anymore – Romeno Nov 23 '18 at 10:49
4

No, it does not follow the runlevel model. Ubuntu has moved away from sysV init to upstart instead. The main reason for this was to parallelize the initialization process to vastly reduce boot time.

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