init(5) File Formats Manual init(5)
init - Upstart init daemon job configuration
On startup, the Upstart init(8) daemon reads its job configuration from the /etc/init directory, and watches for future changes using ino-
Files in this directory must end in .conf and may also be present in sub-directories.
Each file defines a single service or task, with the name taken from its relative path within the directory without the extension. For
example a job defined in /etc/init/rc-sysinit.conf is named rc-sysinit, while a job defined in /etc/init/net/apache.conf is named
These files are plain text and should not be executable.
Each line begins with a configuration stanza and continues until either the end of the line or a line containing a closing stanza. Line
breaks within a stanza are permitted within single or double quotes, or if preceeded by a blackslash.
Stanzas and their arguments are delimited by whitespace, which consists of one or more space or tab characters which are otherwise ignored
unless placed within single or double quotes.
Comments begin with a `#' and continue until the end of the line. Blank lines and lines consisting only of whitespace or comments are
The primary use of jobs is to define services or tasks to be run by the init(8) daemon. Each job may have one or more different processes
run as part of its lifecycle, with the most common known as the main process.
The main process is defined using either the exec or script stanzas, only one of which is permitted. These specify the executable or shell
script that will be run when the job is considered to be running. Once this process terminates, the job stop.
All processes are run with the full job environment available as environment variables in their process.
exec COMMAND [ ARG ]...
This stanza defines the process to be run as the name of an executable on the filesystem, and zero or more arguments to be passed to
it. Any special characters, e.g. quotes or `$' specified will result in the entire command being passed to a shell for expansion.
exec /usr/sbin/acpid -c $EVENTSDIR -s $SOCKET
script ... end script
This stanza defines the process to be run as a shell script that will be executed using sh(1). The -e shell option is always used,
so any command that fails will terminate the script.
The script stanza appears on its own on a line, the script is everything up until the first end script stanza appearing on its own
on a line.
dd bs=1 if=/proc/kmsg of=$KMSGSINK
exec /sbin/klogd -P $KMSGSINK
There an additional four processes that may be run as part of the job's lifecycle. These are specified as the process name, followed by an
exec or script stanza.
This process will be run after the job's starting(7) event has finished, but before the main process is run. It is typically used
to prepare the environment, such as making necessary directories.
This process will be run before the job's started(7) event is emitted, but after the main process has been spawned. It is typically
used to send necessary commands to the main process, or to delay the started(7) event until the main process is ready to receive
This process is run if the job is stopped by an event listed in its stop on stanza or by the stop(8) command. It will be run before
the job's stopping(7) event is emitted and before the main process is killed. It is typically used to send any necessary shutdown
commands to the main process, and it may also call the start(8) command without arguments to cancel the stop.
This process is run after the main process has been killed and before the job's stopped(7) event is emitted. It is typically used
to clean up the environment, such as removing temporary directories.
All of these process, including the main process, are optional. Services without a main process will appear to be running until they are
stopped, this is commonly used to define states such as runlevels. It's quite permissable to have no main process, but to have pre-start
and post-stop processes for the state.
pre-start exec ifup -a
post-stop exec ifdown -a
Jobs can be manually started and stopped at any time by a system adminstrator using the. start(8) and stop(8) tools, however it is far
more useful for jobs to be started and stopped automatically by the init(8) daemon when necessary.
This is done by specifying which events should cause your job to be started, and which cause your process to be stopped again.
The set of possible events is limitless, however there are a number of standard events defined by the init(8) daemon and telinit(8) tools
that you will want to use.
When first started, the init(8) daemon will emit the startup(7) event. This will activate jobs that implement System V compatibility and
the runlevel(7) event. As jobs are started and stopped, the init(8) daemon will emit the starting(7), started(7), stopping(7) and
stopped(7) events on their behalf.
start on EVENT [[KEY=]VALUE]... [and|or...]
The start on stanza defines the set of events that will cause the job to be automatically started. Each EVENT is given by its name.
Multiple events are permitted using the and & or operators, and complex expressions may be performed with parentheses (within which
line breaks are permitted).
You may also match on the environment variables contained within the event by specifying the KEY and expected VALUE. If you know
the order in which the variables are given to the event you may omit the KEY.
VALUE may contain wildcard matches and globs as permitted by fnmatch(3) and may expand the value of any variable defined with the
Negation is permitted by using != between the KEY and VALUE.
start on started gdm or started kdm
start on device-added SUBSYSTEM=tty DEVPATH=ttyS*
start on net-device-added INTERFACE!=lo
stop on EVENT [[KEY=]VALUE]... [and|or...]
The stop on stanza defines the set of events that will cause the job to be automatically stopped. It has the same syntax as start
VALUE may additionally expand the value of any variable that came from the job's start environment (either the event or the command
that started it).
stop on stopping gdm or stopping kdm
stop on device-removed DEVPATH=$DEVPATH
Each job is run with the environment from the events or commands that started it. In addition, you may define defaults in the job which
may be overridden later and specify which environment variables are exported into the events generated for the job.
The special UPSTART_EVENTS environment variable contains the list of events that started the job, it will not be present if the job was
In addition, the pre-stop and post-stop scripts are run with the environment of the events or commands that stopped the job. THe
UPSTART_STOP_EVENTS environment variable contains the list of events that stopped the job, it will not be present if the job was stopped
All jobs also contain the UPSTART_JOB and UPSTART_INSTANCE environment variables, containing the name of the job and instance. These are
mostly used by the initctl(8) utility to default to acting on the job the commands are called from.
Defines a default environment variable, the value of which may be overriden by the event or command that starts the job.
Exports the value of an environment variable into the starting(7), started(7), stopping(7) and stopped(7) events for this job.
Services, tasks and respawning
Jobs are services by default. This means that the act of starting the job is considered to be finished when the job is running, and that
even exiting with a zero exit status means the service will be respawned.
task This stanza may be used to specify that the job is a task instead. This means that the act of starting the job is not considered to
be finished until the job itself has been run and stopped again, but that existing with a zero exit status means the task has com-
pleted successfully and will not be respawned.
The start(8) command, and any starting(7) or stopping(7) events will block only until a service is running or until a task has finished.
A service or task with this stanza will be automatically started if it should stop abnormally. All reasons for a service stopping,
except the stop(8) command itself, are considered abnormal. Tasks may exit with a zero exit status to prevent being respawned.
respawn limit COUNT INTERVAL
Respawning is subject to a limit, if the job is respawned more than COUNT times in INTERVAL seconds, it will be considered to be
having deeper problems and will be stopped.
This only applies to automatic respawns and not the restart(8) command.
normal exit STATUS|SIGNAL...
Additional exit statuses or even signals may be added, if the job process terminates with any of these it will not be considered to
have failed and will not be respawned.
normal exit 0 1 TERM HUP
By default, only one instance of any job is permitted to exist at one time. Attempting to start a job when it's already starting or run-
ning results in an error.
Multiple instances may be permitted by defining the names of those instances. If an instance with the same name is not already starting or
running, a new instance will be started instead of returning an error.
This stanza defines the names of instances, on its own its not particularly useful since it would just define the name of the single
permitted instance, however NAME expands any variable defined in the job's environment.
These will often be variables that you need to pass to the process anyway, so are an excellent way to limit the instances.
exec /sbin/httpd -c $CONFFILE
exec /sbin/getty -8 38300 $TTY
These jobs appear in the initctl(8) output with the instance name in parentheses, and have the INSTANCE environment variable set in
Upstart provides several stanzas useful for documentation and external tools.
This stanza may contain a description of the job.
description "This does neat stuff"
This stanza may contain the author of the job, often used as a contact for bug reports.
author "Scott James Remnant <email@example.com>"
This stanza may contain version information about the job, such as revision control or package version number. It is not used or
interpreted by init(8) in any way.
All processes on the system are free to emit their own events by using the initctl(8) tool, or by communicating directly with the
This stanza allows a job to document in its job configuration what events it emits itself, and may be useful for graphing possible
Many common adjustments to the process environment, such as resource limits, may be configured directly in the job rather than having to
handle them yourself.
By default the standard input, output and error file descriptors of jobs are connected to /dev/null
If this stanza is specified, they are connected to /dev/console instead.
console owner is special, it not only connects the job to the system console but sets the job to be the owner of the system console,
which means it will receive certain signals from the kernel when special key combinations such as Control-C are pressed.
A common configuration is to set the file mode creation mask for the process. UMASK should be an octal value for the mask, see
umask(2) for more details.
Another common configuration is to adjust the process's nice value, see nice(1) for more details.
Normally the OOM killer regards all processes equally, this stanza advises the kernel to treat this job differently.
ADJUSTMENT may be an integer value from -16 (very unlikely to be killed by the OOM killer) up to 14 (very likely to be killed by the
OOM killer). It may also be the special value never to have the job ignored by the OOM killer entirely.
Runs the job's processes in a chroot(8) environment underneath DIR
Note that DIR must have all the necessary system libraries for the process to be run, often including /bin/sh
Runs the job's processes with a working directory of DIR instead of the root of the filesystem.
limit LIMIT SOFT|unlimited HARD|unlimited
Sets initial system resource limits for the job's processes. LIMIT may be one of core, cpu, data, fsize, memlock, msgqueue, nice,
nofile, nproc, rss, rtprio, sigpending or stack.
Limits are specified as both a SOFT value and a HARD value, both of which are integers. The special value unlimited may be speci-
fied for either.
kill timeout INTERVAL
Specifies the interval between sending the job's main process the SIGTERM and SIGKILL signals when stopping the running job.
Specifies that the job's main process will raise the SIGSTOP signal to indicate that it is ready. init(8) will wait for this signal
before running the job's post-start script, or considering the job to be running.
init(8) will send the process the SIGCONT signal to allow it to continue.
Specifies that the job's main process is a daemon, and will fork twice after being run. init(8) will follow this daemonisation, and
will wait for this to occur before running the job's post-start script or considering the job to be running.
Without this stanza init(8) is unable to supervise daemon processes and will believe them to have stopped as soon as they daemonise
Specifies that the job's main process will fork once after being run. init(8) will follow this fork, and will wait for this to
occur before running the job's post-start script or considering the job to be running.
Without this stanza init(8) is unable to supervise forking processes and will believe them to have stopped as soon as they fork on
Upstart 2010-02-04 init(5)