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:

•   fork(2) and have the parent process exit(3) or _exit(2).
•   Call daemon(3)

A daemon or agent launched by launchd SHOULD NOT do the following as a part of their startup initialization:

•   Setup the user ID or group ID.
•   Setup the working directory.
•   chroot(2)
•   setsid(2)
•   Close "stray" file descriptors.
•   Change stdio(3) to /dev/null.
•   Setup resource limits with setrusage(2).
•   Setup priority with setpriority(2).
•   Ignore the SIGTERM signal.

A daemon or agent launched by launchd SHOULD:

•   Launch on demand given criteria specified in the XML property list. More information can be found in launch(3).
•   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 files are expected to have their name end in ".plist" but that is not strictly required.

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. The default is the user who submitted the job to launchd.

GroupName <string>
This optional key specifies the user to run the job as. The default is the group of the user who submitted the job to launchd.

inetdCompatibility <dictionary>
The presence of this key specifies that the daemon expects to be run as if it were launched from inetd(8). This flag is incompatible with the ServiceIPC key.

Wait <boolean>
This flag corresponds to the "wait" or "nowait" option of inetd(8).

ProgramArguments <array of strings>
This required key maps to the second argument of execvp(3).

Program <string>
This optional key maps to the first argument of execvp(3). If this key is missing, then the first element of the array of strings provided to the ProgramArguments will be used instead.

OnDemand <boolean>
This optional key is used to control whether your job is launched based on demand or to be kept continuously running. The default is true.

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 specific a directory to chroot(2) to before running the job.

WorkingDirectory <string>
This optional key is used to specific a directory to chdir(2) to before running the job.

ServiceDescription <string>
This optional key is used to specify a human readable description of the purpose of 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.

ServiceIPC <boolean>
This optional key specifies whether the job participates in advanced communication with launchd. The default is false. This flag is incompatible with the inetdCompatibility key.

TimeOut <integer>
The recommended time out 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.

InitGroups <boolean>
This optional key specifies whether the job should have initgroups(3) be called before running the job. The default is false.

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 modifications. The difference being that the job will only be started if the path is a directory and the directory is not empty.

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>
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 computer 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 temporarily to LOG_DEBUG while dealing with this job.

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.

LowPriorityIO <boolean>
This optional key specifies whether the kernel should consider this daemon to be low priority when doing file system I/O.

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 can check-in and 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 dictionary key will be an array of descriptors. Daemon/Agent writers should consider all descriptors of a given key to be to be effectively equivalent, even though each file descriptor likely represents a different networking protocol which conforms to the criteria specified in the job configuration file.

The paramters 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.

Bonjour <boolean or string or array of strings>
This optional key can be used to request that the service be registered with the mDNSResponder(8). If the value is boolean, the service 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, otherwise the results are undefined.

EXAMPLE XML PROPERTY LISTS

The following XML Property List simply keeps "exampled" running continuously:

    <?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>OnDemand</key>
    <false/>
    </dict>
    </plist>

FILES
~/Library/LaunchAgents
    Per-user agents provided by the user.
/Library/LaunchAgents
    Per-user agents provided by the administrator.
/Library/LaunchDaemons
    System wide daemons provided by the administrator.
/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)