Startup Items
Published: 2016-09-13 · Archived: 2026-04-05 20:36:39 UTC
A startup item is a specialized bundle whose code is executed during the final phase of the boot process, and at other
predetermined times (see Managing Startup Items). The startup item typically contains a shell script or other executable file
along with configuration information used by the system to determine the execution order for all startup items.
The /System/Library/StartupItems directory is reserved for startup items that ship with OS X. All other startup items
should be placed in the /Library/StartupItems directory. Note that this directory does not exist by default and may need
to be created during installation of the startup item.
Anatomy of a Startup Item
Unlike many other bundled structures, a startup item does not appear as an opaque file in the Finder. A startup item is a
directory whose executable and configuration property list reside in the top-level directory. The name of the startup item
executable must match the name of the startup item itself. The name of the configuration property list is always
StartupParameters.plist . Depending on your needs, you may also include other files in your startup item bundle
directory.
MyStartupItem/
 |
 |- MyStartupItem
 \- StartupParameters.plist
To create your startup item:
1. Create the startup item directory. The directory name should correspond to the behavior you’re providing.
Example: MyDBServer
2. Add your executable to the directory. The name of your executable should be exactly the same as the directory name.
For more information, see Creating the Startup Item Executable.
3. Create a property list with the name StartupParameters.plist and add it to the directory. For information on the
keys to include in this property list, see Specifying the Startup Item Properties .
Example: MyDBServer/StartupParameters.plist
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4. Create an installer to place your startup item in the /Library/StartupItems directory of the target system. (Your
installer may need to create this directory first.)
Your installer script should set the permissions of the startup item directory to prevent non-root users from modifying
the startup item or its contents. For more information, see Startup Item Permissions.
Creating the Startup Item Executable
The startup item executable can be a binary executable file or an executable shell script. Shell scripts are more commonly
used because they are easier to create and modify.
If you are implementing your startup item executable as a shell script, OS X provides some code to simplify the process of
creating your script. The file /etc/rc.common defines routines for processing command-line arguments and for gathering
system settings. In your shell script, source the rc.common file and call the RunService routine, passing it the first
command-line argument, as shown in the following example:
#!/bin/sh
. /etc/rc.common
 
# The start subroutine
StartService() {
 # Insert your start command below. For example:
 mydaemon -e -i -e -i -o
 # End example.
}
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# The stop subroutine
StopService() {
 # Insert your stop command(s) below. For example:
 killall -TERM mydaemon
 sleep 10
 killall -9 mydaemon
 # End example.
}
 
# The restart subroutine
RestartService() {
 # Insert your start command below. For example:
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killall -HUP mydaemon
 # End example.
}
 
RunService "$1"
The RunService routine looks for StartService , StopService , and RestartService functions in your shell script and
calls them to start, stop, or restart your services as needed. You must provide implementations for all three routines, although
the implementations can be empty for routines whose commands your service does not support.
If your startup-item executable contains code that might take a long time to finish, consider spawning off a background
process to run that code. Performing lengthy startup tasks directly from your scripts delays system startup. Your startup item
script should execute as quickly as possible and then exit.
For more information about writing shell scripts, see Shell Scripting Primer.
Specifying the Startup Item Properties
The configuration property list of a startup item provides descriptive information about the startup item, lists the services it
provides, and lists its dependencies on other services. OS X uses the service and dependency information to determine the
launch order for startup items. This property list is stored in ASCII format (as opposed to XML) and can be created using the
Property List Editor application.
Table A-1 lists the key-value pairs you can include in your startup item’s StartupParameters.plist file. Each of the listed
arrays contains string values. You can use the Property List Editor application that comes with the Xcode Tools to create this
property list. When saving your property-list file, be sure to save it as an ASCII property-list file.
Table A-1  StartupParameters.plist key-value pairs
Key Type Value
Description String A short description of the startup item, used by administrative tools.
Provides Array The names of the services provided by this startup item. Although a startup item can potentially
provide multiple services, it is recommended that you limit your startup items to only one
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service each.
Requires Array
The services provided by other startup items that must be running before this startup item can
be started. If the required services are not available, this startup item is not run.
Uses Array
The services provided by other startup items that should be started before this startup item, but
which are not required. The startup item should be able to start without the availability of these
services.
For example, here is an old-style plist:
{
 Description = "Software Update service";
 Provides = ("SoftwareUpdateServer");
 Requires = ("Network");
 Uses = ("Network");
 OrderPreference = "Late";
 Messages =
 {
 start = "Starting Software Update service";
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stop = "Stopping Software Update service";
 };
}
And here is an XML plist example:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist SYSTEM "file://localhost/System/Library/DTDs/PropertyList.dtd">
<plist version="0.9">
 <dict>
 <key>Description</key>
 <string>Apple Serial Terminal Support</string>
 <key>OrderPreference</key>
 <string>Late</string>
 <key>Provides</key>
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<array>
 <string>Serial Terminal Support</string>
 </array>
 <key>Uses</key>
 <array>
 <string>SystemLog</string>
 </array>
 </dict>
</plist>
The service names you specify in the Requires and Uses arrays may not always correspond directly to the name of the
startup item that provides that service. The Provides property specifies the actual name of the service provided by a
startup item, and while this name usually matches the name of the startup item, it is not required to do so. For example, if the
startup item launches multiple services, only one of those services can have the same name as the startup item.
If two startup items provide a service with the same name, the system runs only the first startup item it finds with that name.
This is one of the reasons why your own startup items should launch only one service. If the name of only one of the
services matches the name of another service, the entire startup item might not be executed and neither service would be
launched.
The values of the Requires and Uses keys do not guarantee a particular launch order.
In OS X v10.4 and later, most low-level services are started with launchd . By the time your startup item starts executing,
launchd is running, and any attempt to access any of the services provided by a launchd daemon will result in that
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daemon starting. Thus, you can safely assume (or at least pretend) that any of these services are running by the time your
startup item is called.
For this reason, with few exceptions, the Requires and Uses keys are largely irrelevant after OS X v10.3 except to
support service dependencies between two or more third-party startup items.
Managing Startup Items
During the boot process, the system launches the available startup items, passing a start argument to the startup item
executable. After the boot process, the system may run the startup item executable again, this time passing it a restart or
stop argument. Your startup item executable should check the supplied argument and act accordingly to start, restart, or
stop the corresponding services.
If you want to start, restart, or stop startup items from your own scripts, you can do so using the SystemStarter program.
To use SystemStarter , you must execute it with two parameters: the desired action and the name of the service provided
by the startup item. For example, to restart the Apache Web server (prior to OS X v10.4), you would execute the following
command:
/sbin/SystemStarter restart "Web Server"
Startup items should always respect the arguments passed in by SystemStarter . However, the response to those arguments
is dependent on the startup item. The stop and restart options may not make sense in all cases. Your startup item could also
support the restart option using the existing code for stopping and starting its service.
Displaying and Localizing a Startup Message
When your startup item starts at boot time, you may (if desired) display a message to the user. To do this, use the
ConsoleMessage command. (You can use this command even if the computer is not starting up, but the user will not see it
unless the Console application is running.)
For example:
ConsoleMessage "MyDaemon is running. Better go catch it."
If you want to localize the message displayed when a startup item starts, you must create a series of property list files with
localized versions of the strings. Each of these files must be named Localizable.strings , and must be in a localized
project directory whose name is based on the name of a language or locale code for the desired language. These folders, in
turn, must be in a folder called Resources in the startup item folder.
For example, you might create a tree structure that looks like this:
MyDaemon
 |
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|- MyDaemon
 |- StartupParameters.plist
 \- Resources
 |
 |- English.lproj
 |- French.lproj
 |- German.lproj
 \- zh_CN.lproj
Within each of these localizable strings files, you must include a dictionary whose keys map an English string to a string in
another language. For example, the French version of the PrintingServices localization file looks like this:
<?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>
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<key>Starting printing services</key>
 <string>Démarrage des services d’impression</string>
 </dict>
</plist>
Whenever the ConsoleMessage command is passed the string “Starting printing services”, if the user’s language preference
is French, the user will instead see “Démarrage des services d’impression” at startup. C’est très bien!
The value of the key field must precisely match the English string printed by your startup item using ConsoleMessage .
See the manual page for locale for more information about locale codes.
Startup Item Permissions
Because startup items run with root authority, you must make sure your startup item directory permissions are set correctly.
For security reasons, your startup item directory should be owned by root, the group should be set to wheel, and the
permissions for the directory should be 755 (rwxr-xr-x). This means that only the root user can modify the directory
contents; other users can examine the directory and view its contents, but cannot modify them. The files inside the directory
should have similar permissions and ownership. Thus, the file listing for the Apache startup item directory is as follows:
./Apache:
total 16
drwxr-xr-x 4 root wheel 136 Feb 14 14:33 .
drwxr-xr-x 21 root wheel 714 Feb 14 15:03 ..
-rwxr-xr-x 1 root wheel 1253 Feb 10 19:31 Apache
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-rw-r--r-- 1 root wheel 152 Feb 10 19:31 StartupParameters.plist
Source: https://developer.apple.com/library/content/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/StartupItems.html
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