Linux changes the run-level:
- (Old Linux distro) SysV init uses run-level number from 0 to 6.
- cmdline: init, telinit, who
- (New Linux distro) systemd init uses systemd targets.
- cmdline: systemctl
Linux runlevel defines the state of the OS.
| SysV | Systemd targets | Description |
|---|---|---|
| 0 |
runlevel0.target poweroff.target | Halt or shutdown the Linux system |
| 1 |
runlevel1.target rescue.target |
Single-user text mode (useful for maintenance mode) |
| 2 | runlevel2.target multi-user.target |
Not used |
| 3 | runlevel3.target multi-user.target |
Full multi-user text mode (used on Linux servers) |
| 4 | runlevel4.target multi-user.target |
Not used |
| 5 | runlevel5.target graphical.target |
Full multi-user GUI mode. You can use X-based login screen. Useful for Linux desktop |
| 6 | runlevel6.target reboot.target |
Reboot Linux system |
Comparing the cmdline used.
| SysV | Systemd | Description |
|---|---|---|
| runelvel who -r |
systemctl get-default |
Show the current runlevel |
| init 1 |
systemctl rescue systemctl emergency |
Change the runlevel to single user mode for maintenance |
| init 3 |
systemctl multi-user-target | Change to multi-user text mode |
| init 0 |
systemctl poweroff | Poweroff |
| init 6 |
systemctl reboot |
Reboot |
| systemctl default | Back to default target |
|
| init 5 |
systemctl graphical.target |
Change to GUI mode |
Links:
- https://www.cyberciti.biz/tips/linux-changing-run-levels.html