launchd.plist(5) BSD File Formats Manual launchd.plist(5)
NAME
launchd.plist -- System wide and per-user daemon/agent configuration
files
DESCRIPTION
This document details the parameters that can be given to an XML property
list that can be loaded into launchd with launchctl.
EXPECTATIONS
Daemons or agents managed by launchd are expected to behave certain ways.
A daemon or agent launched by launchd MUST NOT do the following in the
process directly launched by launchd:
o Call daemon(3).
o Do the moral equivalent of daemon(3) by calling fork(2) and
have the parent process exit(3) or _exit(2).
A daemon or agent launched by launchd SHOULD NOT do the following as a
part of their startup initialization:
o Setup the user ID or group ID.
o Setup the working directory.
o chroot(2)
o setsid(2)
o Close "stray" file descriptors.
o Change stdio(3) to /dev/null.
o Setup resource limits with setrusage(2).
o Setup priority with setpriority(2).
o Ignore the SIGTERM signal.
A daemon or agent launched by launchd SHOULD:
o Launch on demand given criteria specified in the XML property
list. More information can be found later in this man page.
o Catch the SIGTERM signal.
XML PROPERTY LIST KEYS
The follow keys can be used to describe the configuration details of your
daemon or agent. Property lists are Apple's standard configuration file
format. Please see plist(5) for more information. Please note. Property
list files are expected to have their name end in ".plist".
Label <string>
This required key uniquely identifies the job to launchd.
Disabled <boolean>
This optional key is used to disable your job. The default is false.
UserName <string>
This optional key specifies the user to run the job as. This key is only
applicable when launchd is running as root.
GroupName <string>
This optional key specifies the group to run the job as. This key is only
applicable when launchd is running as root. If UserName is set and Group-
Name is not, the the group will be set to the default group of the user.
inetdCompatibility <dictionary>
The presence of this key specifies that the daemon expects to be run as
if it were launched from inetd.
Wait <boolean>
This flag corresponds to the "wait" or "nowait" option of inetd. If
true, then the listening socket is passed via the standard
in/out/error file descriptors. If false, then accept(2) is called
on behalf of the job, and the result is passed via the standard
in/out/error descriptors.
LimitLoadToHosts <array of strings>
This configuration file only applies to the hosts listed with this key.
LimitLoadFromHosts <array of strings>
This configuration file only applies to hosts NOT listed with this key.
LimitLoadToSessionType <string>
This configuration file only applies to sessions of the type specified.
This key is used in concert with the -S flag to launchctl.
Program <string>
This key maps to the first argument of execvp(3). If this key is miss-
ing, then the first element of the array of strings provided to the Pro-
gramArguments will be used instead. This key is required in the absence
of the ProgramArguments key.
ProgramArguments <array of strings>
This key maps to the second argument of execvp(3). This key is required
in the absence of the Program key. Please note! Many people are confused
by this key. Please read execvp(3) very carefully!
EnableGlobbing <boolean>
This flag causes launchd to use the glob(3) mechanism to update the pro-
gram arguments before invocation.
OnDemand <boolean>
This key was used in Mac OS X 10.4 to control whether a job was kept
alive or not. The default was true. This key has been deprecated and
replaced in Mac OS X 10.5 with the more powerful KeepAlive option.
KeepAlive <boolean or dictionary of stuff>
This optional key is used to control whether your job is to be kept con-
tinuously running or to let demand and conditions control the invocation.
The default is false and therefore only demand will start the job. The
value may be set to true to unconditionally keep the job alive. Alterna-
tively, a dictionary of conditions may be specified to selectively con-
trol whether launchd keeps a job alive or not. If multiple keys are pro-
vided, launchd ORs them, thus providing maximum flexibility to the job to
refine the logic and stall if necessary. If launchd finds no reason to
restart the job, it falls back on demand based invocation. Jobs that
exit quickly and frequently when configured to be kept alive will be
throttled to converve system resources.
SuccessfulExit <boolean>
If true, the job will be restarted as long as the program exits and
with an exit status of zero. If false, the job will be restarted
in the inverse condition. This key implies that "RunAtLoad" is set
to true, since the job needs to run at least once before we can get
an exit status.
NetworkState <boolean>
If true, the job will be kept alive as long as the network is up,
where up is defined as at least one non-loopback interface being up
and having IPv4 or IPv6 addresses assigned to them. If false, the
job will be kept alive in the inverse condition.
PathState <dictionary of booleans>
Each key in this dictionary is a file-system path. If the value of
the key is true, then the job will be kept alive as long as the
path exists. If false, the job will be kept alive in the inverse
condition. The intent of this feature is that two or more jobs may
create semaphores in the file-system namespace.
OtherJobEnabled <dictionary of booleans>
Each key in this dictionary is the label of another job. If the
value of the key is true, then this job is kept alive as long as
that other job is enabled. Otherwise, if the value is false, then
this job is kept alive as long as the other job is disabled. This
feature should not be considered a substitute for the use of IPC.
RunAtLoad <boolean>
This optional key is used to control whether your job is launched once at
the time the job is loaded. The default is false.
RootDirectory <string>
This optional key is used to specify a directory to chroot(2) to before
running the job.
WorkingDirectory <string>
This optional key is used to specify a directory to chdir(2) to before
running the job.
EnvironmentVariables <dictionary of strings>
This optional key is used to specify additional environmental variables
to be setup before running the job.
Umask <integer>
This optional key specifies what value should be passed to umask(2)
before running the job. Known bug: Property lists don't support octal, so
please convert the value to decimal.
TimeOut <integer>
The recommended idle time out (in seconds) to pass to the job. If no
value is specified, a default time out will be supplied by launchd for
use by the job at check in time.
ExitTimeOut <integer>
The amount of time launchd waits before sending a SIGKILL signal. The
default value is 20 seconds. The value zero is interpreted as infinity.
ThrottleInterval <integer>
This key lets one override the default throttling policy imposed on jobs
by launchd. The value is in seconds, and by default, jobs will not be
spawned more than once every 10 seconds. The principle behind this is
that jobs should linger around just in case they are needed again in the
near future. This not only reduces the latency of responses, but it
encourages developers to amortize the cost of program invocation.
InitGroups <boolean>
This optional key specifies whether the job should have initgroups(3) be
called before running the job. The default is true in 10.5 and false in
10.4. This key will be ignored if the UserName key is not set.
WatchPaths <array of strings>
This optional key causes the job to be started if any one of the listed
paths are modified.
QueueDirectories <array of strings>
Much like the WatchPaths option, this key will watch the paths for modi-
fications. The difference being that the job will only be started if the
path is a directory and the directory is not empty.
StartOnMount <boolean>
This optional key causes the job to be started every time a filesystem is
mounted.
StartInterval <integer>
This optional key causes the job to be started every N seconds. If the
system is asleep, the job will be started the next time the computer
wakes up. If multiple intervals transpire before the computer is woken,
those events will be coalesced into one event upon wake from sleep.
StartCalendarInterval <dictionary of integers or array of dictionary of
integers>
This optional key causes the job to be started every calendar interval as
specified. Missing arguments are considered to be wildcard. The semantics
are much like crontab(5). Unlike cron which skips job invocations when
the computer is asleep, launchd will start the job the next time the com-
puter wakes up. If multiple intervals transpire before the computer is
woken, those events will be coalesced into one event upon wake from
sleep.
Minute <integer>
The minute on which this job will be run.
Hour <integer>
The hour on which this job will be run.
Day <integer>
The day on which this job will be run.
Weekday <integer>
The weekday on which this job will be run (0 and 7 are Sunday).
Month <integer>
The month on which this job will be run.
StandardOutPath <string>
This optional key specifies what file should be used for data being sent
to stdout when using stdio(3).
StandardErrorPath <string>
This optional key specifies what file should be used for data being sent
to stderr when using stdio(3).
Debug <boolean>
This optional key specifies that launchd should adjust its log mask tem-
porarily to LOG_DEBUG while dealing with this job.
WaitForDebugger <boolean>
This optional key specifies that launchd should instruct the kernel to
have the job wait for a debugger to attach before any code in the job is
executed.
SoftResourceLimits <dictionary of integers>
HardResourceLimits <dictionary of integers>
Resource limits to be imposed on the job. These adjust variables set with
setrlimit(2). The following keys apply:
Core <integer>
The largest size (in bytes) core file that may be created.
CPU <integer>
The maximum amount of cpu time (in seconds) to be used by each
process.
Data <integer>
The maximum size (in bytes) of the data segment for a process; this
defines how far a program may extend its break with the sbrk(2)
system call.
FileSize <integer>
The largest size (in bytes) file that may be created.
MemoryLock <integer>
The maximum size (in bytes) which a process may lock into memory
using the mlock(2) function.
NumberOfFiles <integer>
The maximum number of open files for this process.
NumberOfProcesses <integer>
The maximum number of simultaneous processes for this user id.
ResidentSetSize <integer>
The maximum size (in bytes) to which a process's resident set size
may grow. This imposes a limit on the amount of physical memory to
be given to a process; if memory is tight, the system will prefer
to take memory from processes that are exceeding their declared
resident set size.
Stack <integer>
The maximum size (in bytes) of the stack segment for a process;
this defines how far a program's stack segment may be extended.
Stack extension is performed automatically by the system.
Nice <integer>
This optional key specifies what nice(3) value should be applied to the
daemon.
AbandonProcessGroup <boolean>
When a job dies, launchd kills any remaining processes with the same
process group ID as the job. Setting this key to true disables that
behavior.
HopefullyExitsFirst <boolean>
This optional key causes programs to exit earlier during system shutdown.
This key exists because some jobs do more than flush buffers and exit
like they're supposed to. The use of this key should be considered a tem-
porary solution until the software can be changed to only flush dirty
buffers and then exit.
HopefullyExitsLast <boolean>
This optional key causes programs to exit later during system shutdown.
This key exists because some jobs don't reference count their clients,
and therefore do not know when it is safe to exit. The use of this key
should be considered a temporary solution until the software can be
changed to properly reference count clients.
LowPriorityIO <boolean>
This optional key specifies whether the kernel should consider this dae-
mon to be low priority when doing file system I/O.
LaunchOnlyOnce <boolean>
This optional key specifies whether the job can only be run once and only
once. In other words, if the job cannot be safely respawned without a
full machine reboot, then set this key to be true.
MachServices <dictionary of booleans or a dictionary of dictionaries>
This optional key is used to specify Mach services to be registered with
the Mach bootstrap sub-system. Each key in this dictionary should be the
name of service to be advertised. The value of the key must be a boolean
and set to true. Alternatively, a dictionary can be used instead of a
simple true value.
ResetAtClose <boolean>
If this boolean is false, the port is recycled, thus leaving
clients to remain oblivious to the demand nature of job. If the
value is set to true, clients receive port death notifications when
the job lets go of the receive right. The port will be recreated
atomically with respect to bootstrap_look_up() calls, so that
clients can trust that after receiving a port death notification,
the new port will have already been recreated. Setting the value to
true should be done with care. Not all clients may be able to han-
dle this behavior. The default value is false.
HideUntilCheckIn <boolean>
Reserve the name in the namespace, but cause bootstrap_look_up() to
fail until the job has checked in with launchd.
Finally, for the job itself, the values will be replaced with Mach ports
at the time of check-in with launchd.
Sockets <dictionary of dictionaries... OR dictionary of array of
dictionaries...>
This optional key is used to specify launch on demand sockets that can be
used to let launchd know when to run the job. The job must check-in to
get a copy of the file descriptors using APIs outlined in launch(3). The
keys of the top level Sockets dictionary can be anything. They are meant
for the application developer to use to differentiate different which
descriptors correspond to which application level protocols (e.g. http
vs. ftp vs. DNS...). At check in time, the value of each Sockets dictio-
nary key will be an array of descriptors. Daemon/Agent writers should
consider all descriptors of a given key to be to be effectively equiva-
lent, even though each file descriptor likely represents a different net-
working protocol which conforms to the criteria specified in the job con-
figuration file.
The parameters below are used as inputs to call getaddrinfo(3).
SockType <string>
This optional key tells launchctl what type of socket to create.
The default is "stream" and other valid values for this key are
"dgram" and "seqpacket" respectively.
SockPassive <boolean>
This optional key specifies whether listen(2) or connect(2) should
be called on the created file descriptor. The default is true ("to
listen").
SockNodeName <string>
This optional key specifies the node to connect(2) or bind(2) to.
SockServiceName <string>
This optional key specifies the service on the node to connect(2)
or bind(2) to.
SockFamily <string>
This optional key can be used to specifically request that "IPv4"
or "IPv6" socket(s) be created.
SockProtocol <string>
This optional key specifies the protocol to be passed to socket(2).
The only value understood by this key at the moment is "TCP".
SockPathName <string>
This optional key implies SockFamily is set to "Unix". It specifies
the path to connect(2) or bind(2) to.
SecureSocketWithKey <string>
This optional key is a variant of SockPathName. Instead of binding
to a known path, a securely generated socket is created and the
path is assigned to the environment variable that is inherited by
all jobs spawned by launchd.
SockPathMode <integer>
This optional key specifies the mode of the socket. Known bug:
Property lists don't support octal, so please convert the value to
decimal.
Bonjour <boolean or string or array of strings>
This optional key can be used to request that the service be regis-
tered with the mDNSResponder(8). If the value is boolean, the ser-
vice name is inferred from the SockServiceName.
MulticastGroup <string>
This optional key can be used to request that the datagram socket
join a multicast group. If the value is a hostname, then
getaddrinfo(3) will be used to join the correct multicast address
for a given socket family. If an explicit IPv4 or IPv6 address is
given, it is required that the SockFamily family also be set, oth-
erwise the results are undefined.
DEPENDENCIES
Unlike many bootstrapping daemons, launchd has no explicit dependency
model. Interdependencies are expected to be solved through the use of
IPC. It is therefore in the best interest of a job developer who expects
dependents to define all of the sockets in the configuration file. This
has the added benefit of making it possible to start the job based on
demand instead of immediately.
EXAMPLE XML PROPERTY LISTS
The following XML Property List simply keeps "exampled" running continu-
ously:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC -//Apple Computer//DTD PLIST 1.0//EN
http://www.apple.com/DTDs/PropertyList-1.0.dtd >
<plist version="1.0">
<dict>
<key>Label</key>
<string>com.example.exampled</string>
<key>ProgramArguments</key>
<array>
<string>exampled</string>
</array>
<key>KeepAlive</key>
<true/>
</dict>
</plist>
FILES
~/Library/LaunchAgents Per-user agents provided by the user.
/Library/LaunchAgents Per-user agents provided by the adminis-
trator.
/Library/LaunchDaemons System wide daemons provided by the admin-
istrator.
/System/Library/LaunchAgents Mac OS X Per-user agents.
/System/Library/LaunchDaemons Mac OS X System wide daemons.
SEE ALSO
launchctl(1), launch(3), launchd(8), plist(5)
Darwin September 30, 2004 Darwin
Mac OS X 10.5 - Generated Sun Oct 28 21:44:03 EDT 2007