NAME¶
runlevel - output previous and current runlevel
SYNOPSIS¶
runlevel [
OPTION]... [
UTMP]
DESCRIPTION¶
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.
OPTIONS¶
- --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.
EXIT STATUS¶
runlevel will exit with status
0 if a
UTMP record was
found, otherwise it will exit with status
1.
ENVIRONMENT¶
- 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
FILES¶
- /var/run/utmp
- Where the current and previous runlevels will be read from.
NOTES¶
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.
AUTHOR¶
Written by Scott James Remnant <
scott@netsplit.com>
REPORTING BUGS¶
Report bugs at <
https://launchpad.net/upstart/+bugs>
COPYRIGHT¶
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.
SEE ALSO¶
runlevel(7) init(8) telinit(8) shutdown(8)
who(1)