Provided by: upstart_1.12.1-0ubuntu4_amd64
runlevel - output previous and current runlevel
runlevel [OPTION]... [UTMP]
runlevel reads the system UTMP file, which defaults to /var/run/utmp when no alternate filename is given, to locate the most recent runlevel record. The previous and current runlevel from that record are output separated by a single space. If there is no previous runlevel in the record, the letter N will be substituted. If no runlevel record can be found, runlevel outputs the word unknown and exits with an error. During system boot, the environment variables RUNLEVEL and PREVLEVEL will be set by the init(8) daemon, these come from the runlevel(7) event generated by telinit(8) or shutdown(8). When these environment variables are set, runlevel will output the values from these instead. Thus runlevel can be used in rc scripts as a replacement for the System-V who(1) -r command.
--quiet Does not output the current and previous runlevel, nor does it output unknown in the case of error (but it will exit with an error code). This may be used to test for the presence of a runlevel entry, or to check for errors reading from the file.
runlevel will exit with status 0 if a UTMP record was found, otherwise it will exit with status 1.
RUNLEVEL runlevel will read the current runlevel from this environment variable if set in preference to reading from /var/run/utmp PREVLEVEL runlevel will read the previous runlevel from this environment variable if RUNLEVEL was given, in preference to reading from /var/run/utmp
/var/run/utmp Where the current and previous runlevels will be read from.
The Upstart init(8) daemon does not keep track of runlevels itself, instead they are implemented entirely by its userspace tools. A change of runlevel is signalled by the runlevel(7) event, generated by either the telinit(8) or shutdown(8) tools. This event includes the new runlevel in the RUNLEVEL environment variable, as well as the previous runlevel (obtained from their own environment or from /var/run/utmp) in the PREVLEVEL variable. As well as generating the event, both tools write the new runlevel back to /var/run/utmp and append a new entry to /var/log/wtmp.
Written by Scott James Remnant <firstname.lastname@example.org>
Report bugs at <https://launchpad.net/upstart/+bugs>
Copyright © 2009 Canonical Ltd. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.