on_demand_service_tool—Load and unload on-demand Mach services registered with launchd(8)


on_demand_service_tool -L -l LABEL [OPTION…] COMMAND [ARG…]
on_demand_service_tool -U -l LABEL


On-demand services may be registered with launchd(8) by using the --load form. One or more service names may be registered with the bootstrap server by specifying --mach-service. When a Mach message is sent to any of these services, launchd(8) will invoke COMMAND along with any arguments specified (ARG…). COMMAND must be an absolute pathname.

The --unload form unregisters jobs registered with launchd(8).


  • -L, --load

    Registers a job with launchd(8). --label=LABEL and COMMAND are required. This operation may also be referred to as “load” or “submit”.

  • -U, --unload

    Unregisters a job with launchd(8). --label=LABEL is required. This operation may also be referred to as “unload” or “remove”.

  • -l, --label=LABEL

    LABEL is used as the job label to identify the job to launchd(8). LABEL must be unique within a launchd(8) context.

  • -m, --mach-service=SERVICE

    In conjunction with --load, registers SERVICE with the bootstrap server. Clients will be able to obtain a send right by looking up the SERVICE name with the bootstrap server. When a message is sent to such a Mach port, launchd(8) will invoke COMMAND along with any arguments specified (ARG…) if it is not running. This forms the “on-demand” nature referenced by this tool’s name. This option may appear zero, one, or more times. SERVICE must be unique within a bootstrap context.

  • --help

    Display help and exit.

  • --version

    Output version information and exit.


Registers an on-demand server that will execute catch_exception_tool(1) when a Mach message is sent to a Mach port obtained from the bootstrap server by looking up the name svc:

$ on_demand_service_tool --load --label=catch_exception \
      --mach-service=svc \
      $(which catch_exception_tool) --mach-service=svc \
      --file=/tmp/out --persistent --timeout=0

Unregisters the on-demand server installed above:

$ on_demand_service_tool --unload --label=catch_exception

Exit Status

  • 0


  • 1

    Failure, with a message printed to the standard error stream.

See Also

catch_exception_tool(1), exception_port_tool(1), launchctl(1)


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Copyright 2014 The Crashpad Authors.


Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at


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