I never thought about this before, but I was wondering why they chose runlevel 2. Every other distro and OS I've used default to runlevel 3 (with the exception of AIX which also defaults to runlevel 2).

  • I'm confused, I think you want to edit your question. "Every other distro and OS I've used default to runlevel 2" – George M May 26 '12 at 20:11
  • You're right. That was a typo. – Robert Silvie II May 26 '12 at 20:11
  • 1
    Not an answer to the why but Debian does not differentiate between runlevels 2-5. And if i would have to guess 2 is just the lowest available number so they choose to go with it. – Ulrich Dangel May 26 '12 at 20:16
  • Funnily I stumbled upon this just today. In fact I use mainly ubuntu lts versions (12.04, 14.04 and 16.04). Starting from 16.04 the default runlevel for ubuntu seems to be 5, 12.04 and 14.04 defaulted to 2. – Gizmomogwai Oct 10 '17 at 17:06

The Debian distribution (and hence Ubuntu, which is derived from it) does not define any differences between runlevels 2-5 as a matter of policy. It is up to the local system administrator to make use of runlevels as they see fit.

Since there is no difference between runlevels 2-5, a default runlevel 2 was chosen.


Most distributions imho default to runlevel 5 (RedHat, Fedora, SLES, OpenSuSE) - meaning login with runnung X11 and GUI. You have to specify otherwise, if you do not want a GUI.

But the definition of runlevels does not seem to be fixed.

I rember Solaris used runlevel 5 for poweroff, 0 for halt (without power off).

  • Where is the answer to he question? And Ubuntu doesn't default to RL 5. – Oskar Skog May 17 '17 at 13:50
  • @Oskar Skog: Removed Ubuntu. This is the answer to the second part of the Q. – Nils May 17 '17 at 16:59

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