MAC OS Start Service Optimization Advanced Chapter

First, the start-up service under the Mac main three configurable places

1. Login item, account, System Preferences

2,/system/library/startupitems and/library/startupitems/
3, LAUNCHD system initialization process configuration.

The first two optimizations are relatively simple, this paper mainly introduces the third more complex launchd configuration optimization.
Launchd is a critical process for initializing the system environment under Mac OS. Similar to Linux under the INIT, RC.

Second, Mac OS x start-up principle

1,mac firmware Activates, initializes the hardware, and loads the BootX bootloader.
2,bootx load kernel and kernel extensions (kext).
3, the kernel starts the launchd process.
4,launchd according to/system/library/launchagents,/system/library/launchdaemons,/library/launchdaemons, Library/ Launchagents, ~/library/launchagents in the plist configuration, start the service daemon.

After watching Mac OS x start-up principle, we are not difficult to find/system/library/launchagents,/system/library/launchdaemons,/library/launchdaemons, Library /launchagents the Plist property file in five directories is the key to optimizing the system.

Third, the service catalogue introduction and related concepts:
What are the differences between/system/library and/library and ~/library directories?
The/system/library directory is an apple-developed software store.
The/library directory is a third-party software stored by the system administrator.
~/library/is a third-party software that is stored by users themselves.

The difference between launchdaemons and launchagents?
Launchdaemons is the service (daemon) that the user started before logging in.
Launchagents is the service (daemon) that is started after the user logs on.

iv. plist file format and meaning of each field

The plist file format and the meaning of each field in the five directories mentioned above:

Key	Description	Required
Label	The name of the job	Yes
Programarguments	Strings to pass to the program when it is executed	Yes
UserName	The job would be is run as the given user, who necessarily is the one who submitted it to launchd.	No
Inetdcompatibility	Indicates that the daemon expects to be run as if it were launched by?inetd	No
Program	The path to your executable. This key can save the Programarguments key for flags and arguments.	No
OnDemand	A Boolean flag that defines if a job runs continuously or not	No
RootDirectory	The job would be chrooted?into another directory	No
Serviceipc	Whether The daemon can speak IPC to Launchd	No
Watchpaths	Allows Launchd to start a job based on modifications at a file-system path	No
Queuedirectories	Similar to Watchpath, a queue would only watch a empty directory for new files	No
Startinterval	Used to schedule a job this runs on a repeating schedule. Specified as the number of seconds to wait between runs.	No
Startcalendarinterval	Job scheduling. The?syntax?is similar to?cron.	No
Hardresourcelimits	Controls restriction of the resources consumed by any job	No
Lowpriorityio	Tells the kernel that this task is of a low priority when doing file system I/O	No
Sockets	An array can is used to specify what socket the daemon would listen on for launch on demand	No

Do not understand the above ground plist configuration? It doesn't matter, our optimization strategy is to completely uninstall the service, so we don't have to care about the configuration meaning in plist.

Five, service optimization

To disable the service, we need to use a tool directive provided by Mac OS-launchctl
The LAUNCHCTL directive sets a disable flag for the service, and when Launchd starts, it checks whether the service is disabled to determine whether the service needs to be enabled.

Method of disabling a service 1
Find the Disable flag file/var/db/launchd.db/com.apple.launchd/overrides.plist first, and see if the service you want to disable has been disabled.
Some services have been disabled, but not listed in Overrides.plist. At this point, you also need to check if the plist file for this service has a label field marked as Disable.

After confirming that the service is not disabled, we can disable the service by invoking the following command:
sudo launchctl unload plist file path
sudo launchctl unload-w plist file path
For example, if I want to disable Spotlight, enter
sudo launchctl unload/system/library/launchagents/com.apple.spotlight.plist
sudo launchctl unload-w/system/library/launchagents/com.apple.spotlight.plist

When the service is disabled, restarting the Mac OS can take effect.

Method 2 for disabling services, a more effective and violent approach (recommended)
Uninstall the service first
sudo launchctl unload/system/library/launchagents/com.apple.spotlight.plist
Then the plist file mv to a different directory backup. Reboot. Get. Isn't it simple!

I personally prefer this way of disabling the service, so recommend it.

If the discovery service is disabled and the system or software has an exception, you can restore the service by using the following command:
Method 1:
sudo launchctl load-wf plist file path
Method 2:
The backup plist file mv back to the original folder.
sudo launchctl load plist file path

Note: Disable system-level services with caution, before disabling Google, make sure you are familiar with the role of this service. Doing so may cause the system to fail to start.
The safest thing to do is not to disable it.

Of course, the user Service we can still be assured that disabled, there is a problem at most again to enable Bai.

Here is the list of services I disabled:
/system/library/launchdaemons/com.apple.metadata.mds.plist (prerequisite for disabling Spotlight)
/system/library/launchagents/com.apple.spotlight.plist (Spotlight)
/library/launchdaemons/com.google.keystone.daemon.plist (Google software Update)
/library/launchagents/com.google.keystone.root.agent (Google software Update)
~/library/launchagents/com.google.keystone.agent.plist (Google software Update, the process under the user does not need to add sudo)
~/library/launchagents/com.apple.csconfigdotmaccert-ken.wug\ @me. Com-sharedservices.agent.plist (me.com Shared Services, I don't have to )
/system/library/launchdaemons/org.cups.cupsd.plist (printer)
/system/library/launchdaemons/org.cups.cups-lpd.plist (printer)
/system/library/launchdaemons/com.apple.blued.plist (Bluetooth)
/system/library/launchagents/com.apple.airportbasestationagent.plist (Apple Wireless Base station, I don't have this device)

Know the Daemon (service) name, how to find the corresponding plist file?
Copy the process (service) name and then to/system/library/launchagents,/system/library/launchdaemons,/library/launchdaemons, Library/ Launchagents, ~/library/launchagents five directories, search by the following command:

Ll|grep process (Service) name
Like what
Ll|grep blued
It was found in the/system/library/launchdaemons. Next, please follow the instructions above to disable the service.

MAC OS Start Service Optimization Advanced Chapter