How do I find out runlevel of unix or Linux system?
A runlevel is a software configuration of the system which allows only a selected group of processes to exist. The processes spawned by init command/process for each of these runlevels are defined in the /etc/inittab file. Runlevels 0, 1, and 6 are reserved. Runlevel 0 is used to halt the sys tem, runlevel 6 is used to reboot the system, and runlevel 1 is used to get the system down into single user mode. In order to print current runlevel you need to use command who or runlevel as follows:1) Print print current runlevel using who command:
$ who -r
run-level 2 Dec 16 11:45 last=S2) Find the current and previous system runlevel using runlevel command:
Runlevel reads the system utmp file (typically /var/run/utmp) to locate the runlevel record, and then prints the previous and current system runlevel on its screen. Runlevel can be used in rc scripts as a substitute for the System-V who -r command. However, in newer versions of init this information is also available in the environment variables RUNLEVEL and PREVLEVEL:
$ echo $RUNLEVEL
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