In Debian, as in nearly all Unix/Unux operating systems, run levels from 0 through 6 are available, defined as follows:
- 0: System Halt
- 1: Single User (maintenance)
- 2 to 5: Multi-User Modes
- 6: System Reboot
Note that run levels 2 through 5 are identical in Debian. This is unlike some other distributions, such as RedHat, Fedora, SuSE, or OpenSuSE, which give specific purposes to some of these run levels. For example, run level 2 in these distributions is often defined as one without network support, 3 with networking, 4 with file sharing, and 5 includes a display manager which isn't active in the other run levels.
In most Debian systems, there is no difference between the multiuser run levels, and all of the init scripts default to active in levels 2 through 5. This doesn't mean you can't define your own purposes for different run levels. However, ifyou do choose to do this, do not manually edit the various links to init scripts in the run level directories. The update-re. d command should be used instead. The reason for this is that Debian now defaults to dependency based boot sequencing.
