1/1/2023 0 Comments Capture one for mac 10.5.5![]() ![]() Using IPC is much more subtle than the SystemStarter's keys and requires more work from the developer, but it may lead to cleaner and quicker startups. There are two main strategies when creating launchd dependencies on Tiger: IPC allows daemons to talk amongst themselves to work out dependencies, or daemons can watch files or paths for changes. SystemStarter had a very simple system of dependencies that used the "Uses", "Requires", and "Provides" keys in the plist of a startup item. The hardest part to manage during a launchd boot is dependencies. In fact, the progress bar that appears during boot time is just a placebo application (named WaitingForLoginWindow ) that does not really show anything other than the passage of time. The system only has to register the daemons that are to run and does not actually launch them until they are needed. CAPTURE ONE FOR MAC 10.5.5 MAC OS XMac OS X Tiger, consequently, boots much faster than previous releases. If a process goes into the background, launchd will lose track of it and attempt to relaunch it. In this way it is like watchdogd, and shares watchdogd's requirement that processes do not attempt to fork or daemonize on their own. After a daemon is loaded, launchd will keep track of it and make sure it is running if needed. Rather, launchd will listen on the port, start the daemon when needed, and shut it down when it is no longer needed. If so indicated in the plist by the "OnDemand" key, the daemon is not actually loaded at the time. When launchctl scans through the job plists at boot time, it asks launchd to reserve and listen on all of the ports requested by those jobs. Key to launchd, and similar to xinetd, is the idea of launch-on-demand daemons. Launchd is very different from SystemStarter in that it may not actually launch all the daemons at boot time. These directories are all kept in the typical Library directories of Mac OS X. ![]() These may be scripts or other foreground items, and they can even include a user interface. The LaunchAgents directories contain jobs, called agent applications, that will run as a user or in the context of userland.The LaunchDaemons directories contain items that will run as root, generally background processes.There are two different directories that are scanned: In step 4, the startup scripts scan through a few different directories for jobs to run. launchd runs /etc/rc, various scripts which scan through /System/Library/LaunchDaemons and /Library/LaunchDaemons, calling launchctl on the plists as needed, then launchd starts the login window.BootX loads the kernel, spins the pinwheel cursor, and loads any needed kernel extensions (kexts). ![]()
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