A StartupItem is a MacPorts facility to run “daemons,” a Unix term for programs that run continuously in the background, rather than under the direct control of a user; for example, mail servers, network listeners, etc.
Ports that use StartupItem keywords create scripts for launchd, which is the Apple facility introduced with Mac OS X 10.4 to replace xinetd for starting and managing daemons.
To support +launchd+, a program named +daemondo+ is provided by MacPorts base that serves as an adapter between +launchd+ and daemons (“executable” StartupItems) or traditional Unix startup scripts that start daemons (“script” StartupItems).
There are three categories of StartupItem keywords. Those that trigger StartupItem creation and logging, those that specify attributes of “executable” StartupItems, and those that specify attributes of “script” StartupItems.
The variable startupitem_type in ${prefix}/etc/macports/macports.conf may be set to none to override the default value of the startupitem.type option in Portfiles; this prevents StartupItems from being created.
Additionally, the startupitem_install variable can be set to no in macports.conf to override the default value of the startupitem.install option, which will prevent links from being created under /Library.
This is useful for MacPorts installations that are not used with root privileges.
The keywords in this section may be used with either “executable” or “script” StartupItems (see below).
Whether to automatically load the StartupItem after activating the port.
noExample:
startupitem.autostart yes
Trigger the creation of a StartupItem.
noExample:
startupitem.create yes
Enable additional debug logging.
noExample:
startupitem.debug yes
Whether to install a link to the StartupItem in the appropriate subdirectory of /Library (see +startupitem.location+) so that it can be launched automatically after rebooting.
yesExample:
startupitem.install no
Chooses the subdirectory in which to install the StartupItem. Also affects how it will be loaded: LaunchDaemons must be loaded as root, and only one instance will run for the whole system. LaunchAgents are loaded as a normal user, and one instance per user can run.
LaunchDaemonsExample:
startupitem.location LaunchAgents
Path to a logfile for logging events about the lifetime of the StartupItem. Depending on the type of StartupItem, and the manner in which it is started, standard output from the daemon may also be directed to the logfile.
/dev/nullExample:
startupitem.logfile ${prefix}/var/log/mydaemon.logControl whether or not to log events to the log file. If logevents is set, events with timestamps are logged to the logfile.
noExample:
startupitem.logevents yes
Sets the name for the StartupItem. Defaults to the name of the port, so this keyword is usually unnecessary.
${name}Example:
startupitem.name dhcpd
Cause the daemon to be restarted when a change in network state is detected.
noExample:
startupitem.netchange yes
The type of the StartupItem.
Supported values are launchd for a macOS +launchd+ .plist, or none for no StartupItem.
launchd if on macOS and ${startupitem.create} is true, none otherwiseExample:
startupitem.type launchd
Used when a port needs to install more than one StartupItem, this option consists of a list where alternating elements represent keys and values.
Each key corresponds to one of the startupitem.* options, and the following value is associated with it.
Each StartupItem defined in the list must specify at least a name.
Each other key/value pair is associated with the StartupItem named most recently in the list.
Any keys that are not defined for a given StartupItem will use the value of the corresponding startupitem.* option.
Example:
startupitems name myport-system \
location LaunchDaemons \
executable ${prefix}/sbin/myportd \
name myport-session \
location LaunchAgents \
executable ${prefix}/bin/myport-agentDaemons run continuously, so monitoring the health of daemon processes and restarting them if they die is an important StartupItems' feature. “Executable” StartupItems are preferred over “script” StartupItems because +daemondo+ launches the daemon directly, rather than indirectly via a script, and therefore it automatically knows how to monitor a daemon process and restart it if it dies.
Daemons used with “executable” StartupItems may be programs or scripts (shell, perl, python, etc.) as long as the script itself is the daemon, rather than merely what launches the daemon.
In the latter case “script” StartupItems are to be used.
Since “script” and “executable” are mutually exclusive StartupItem types, the startupitem.executable keyword may not be used in a Portfile that uses any keywords listed in the Script StartupItems section.
Some daemons “daemonize” by detaching themselves from the controlling tty before sending themselves to the background, thus making themselves a child of the original process.
A daemon to be started with startupitem.executable must not be allowed to do this or daemondo will think the process has died and start multiple instances.
Often daemons have a command switch to run in the foreground, and this method should be used for daemons that detach.
Example:
startupitem.executable ${prefix}/sbin/vm-pop3d -d 10 -t 600Do not wrap values in quotes if passing arguments to the daemon; “executable” StartupItem elements must be tagged individually so the spaces between arguments serve as delimiters for “string” tags. For example, this startupitem key/value pair:
startupitem.executable ${prefix}/sbin/vm-pop3d -d 10 -t 600generates a .plist file with these tags:
<key>ProgramArguments</key>
<array>
<string>/opt/local/bin/daemondo</string>
<string>--label=vm-pop3d</string>
<string>--start-cmd</string>
<string>/opt/local/sbin/vm-pop3d</string>
<string>-d</string>
<string>10</string>
<string>-t</string>
<string>600</string>
<string>;</string>
</array>StartupItems of type “script” create a wrapper during port installation for +daemondo+ that will be used to launch a daemon startup script present in an application’s source distribution (MacPorts does not create daemon startup scripts) for daemons that require a script.
“Executable” StartupItems are the preferred type since “script” StartupItems launch daemons indirectly, and this requires that port authors use the startupitem.pidfile keyword so that +daemondo+ can check this pid file to see is a daemon process has died and restart it.
Any time a script (or an executable) itself serves as a daemon, use the “executable” StartupItem type so daemondo will launch it directly and track its health automatically.
Additionally, since “script” and “executable” are mutually exclusive StartupItem types, the startupitem.executable keyword may not be used in a Portfile that uses “script” StartupItem keywords.
A typical snippet of a startup script that may be used with a “script” StartupItem is shown below. Notice that the script is not a daemon; rather the script indirectly launches the vm-pop3d daemon.
#!/bin/sh
case "$1" in
start)
echo -n "Starting vm-pop3d: "
/opt/local/sbin/vm-pop3d -d 10 -t 600
[... trimmed ...]Specify a shell script to start, stop, and restart the daemon.
In the absence of +startupitem.restart+, the daemon will be restarted by taking the stop action, followed by the start action.
Examples:
startupitem.start "${prefix}/share/mysql/mysql.server start"
startupitem.stop "${prefix}/share/mysql/mysql.server stop"
startupitem.restart "${prefix}/share/mysql/mysql.server restart"Wrap the stop, start, and restart values in quotes so they will be placed in the wrapper tagged as a single element.
Shell code that will be executed prior to any of the options +startupitem.start+, startupitem.stop and +startupitem.restart+.
Example:
startupitem.init BIN=${prefix}/sbin/bacula-fdThis keyword must be defined properly for +daemondo+ to be able to monitor daemons launched via “script” StartupItems and restart them if they die.
It specifies two things: a process id (PID) file handling method, and a pidfile name and path.
+
Default: none
${prefix}/var/run/${name}.pid
+
Default: [none] | ${prefix}/var/run/${name}.pid]
Values [none auto manual clean] [+/path/to/pidfile+]
startupitem.pidfile auto ${prefix}/var/run/${name}.pidfile+
+ PID file handling options:
none - daemondo will not create or track a PID file, so it won’t know when a daemon dies.auto - The started process is expected to create a PID file that contains the PID of the running daemon; daemondo then reads the PID from the file and tracks the process. The started process must delete the PID file if this is necessary.clean - The started process is expected to create a PID file that contains the PID of the running daemon; daemondo then reads the PID from the file and tracks the process, and deletes the PID file if it detects the daemon has died.manual - This option should only be used if an “executable” StartupItem could be used (daemondo launches a daemon directly) and a port author wants a PID file written for some special use. A PID file is not needed to detect process death for daemons launched directly by daemondo. As with executable StartupItems, daemondo remembers the PID of the launched process and tracks it automatically.A port with a StartupItem places a link to a .plist file for the port’s daemon within /Library/LaunchDaemons/.
A .plist file is an XML file; MacPorts installs .plist files tagged as “disabled” for the sake of security.
You may enable a startup script (tag the.plist file as “enabled”) and load it into +launchd+ with a single command as shown.
%% sudo launchctl load -w /Library/LaunchDaemons/org.macports.mysql5.plist
You may stop a running startup script, disable it (tag the.plist file as “disabled”), and unload it from +launchd+ with a single command as shown.
%% sudo launchctl unload -w /Library/LaunchDaemons/org.macports.mysql5.plist
During port installation a MacPorts StartupItem creates a .plist file in ${prefix}/etc/LaunchDaemons/, and places a symbolic link to the .plist file within /Library/LaunchDaemons/ if ${startupitem.install} is true.
For example, the StartupItem for the mysql5 port is org.macports.mysql5.plist, and it is linked as shown.
%% ls -l /Library/LaunchDaemons
org.macports.mysql5.plist -> /opt/local/etc/LaunchDaemons/org.macports.mysql5/org.macports.mysql5.plist
For “script” StartupItems, in addition to a .plist file, a wrapper is also created.
%% ls -l /opt/local/etc/LaunchDaemons/org.macports.mysql5/
-rwxr-xr-x 2 root wheel 475 Aug 2 14:16 mysql5.wrapper -rw-r--r-- 2 root wheel 975 Aug 2 14:16 org.macports.mysql5.plist
The wrapper manipulates the script as specified in the startupitem.start and startupitem.stop keywords. An example wrapper script snippet is shown below.
#!/bin/sh
# MacPorts generated daemondo support script
# Start
Start()
{
/opt/local/share/mysql5/mysql/mysql.server start
}
# Stop
Stop()
{
/opt/local/share/mysql5/mysql/mysql.server stop
}
[... trimmed ...]