The rc.boot and rc Bourne shell scripts in /etc perform basic initialization tasks. First the rc.boot script performs a file system consistency check (fscc) and synchronizes memory with the file system (sync). Then the rc script:
Mounts the essential local file systems as defined in the various /etc/fstab configuration files.
Starts the device-driver loader (kextd).
Starts the window server.
Runs the update background process, which periodically flushes the file system cache.
Creates the swap file for the virtual memory system and starts the dynamic pager.
As the final step, the rc script starts the SystemStarter program to process the local and system start-up items. For more information, see “Start-up items,” below.