runlevel — Print previous and current SysV runlevel
runlevel prints the previous and current SysV runlevel if they are known.
The two runlevel characters are separated by a single space character. If a runlevel cannot be determined, N is printed instead. If neither can be determined, the word "unknown" is printed.
Unless overridden in the environment, this will check the utmp database for recent runlevel changes.
If one or both runlevels could be determined, 0 is returned, a non-zero failure code otherwise.
This is a legacy command available for compatibility only. It should not be used anymore, as the concept of runlevels is obsolete.