*BASH User Commands Ubuntu 10.04.4 LTS Server coreutils
runlevel(8)                                                        runlevel(8)

       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

       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 val-
       ues  from  these instead.  Thus runlevel can be used in rc scripts as a
       replacement for the System-V who(1) -r command.

              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 will read the current runlevel  from  this  environment
              variable if set in preference to reading from /var/run/utmp

              runlevel  will  read the previous runlevel from this environment
              variable if RUNLEVEL
               was given, in preference to reading from /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 pre-
       vious  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 <scott@netsplit.com>

       Report bugs at <https://launchpad.net/upstart/+bugs>

       Copyright (C) 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

       runlevel(7) init(8) telinit(8) shutdown(8) who(1)

Upstart                           2009-07-09                       runlevel(8)