Progressively higher-level system processes are given PIDs up to approximately 200, with processes starting from user accounts being given higher process numbers. For instance, the kernel is given number 0, followed by 1 for the parent "launchd" process. Processes can technically be given any number that is not in use however, the system will use number ranges to separate different processes by levels of importance. Whenever processes are started in OS X, they are given a unique identifier number, which can be used to identify it for recognition by other commands (for example, the "kill" utility that terminates processes). We will go through them one-by-one to go over what they do: In order to view them, you can check them by going to the "View" menu and checking the options in the "Columns" menus. The process list shows various attributes about the running processes, many of which are not viewable by default. For instance, you can see in this view that all processes in the system are children of the root launchd "parent", which is the first "userland" process started in the system kernel upon booting (see our previous article on OS X system process organization). Since processes in OS X can launch other ones, this will show which ones are the respective parents and children of each other. One final option for viewing the processes is to see them "heirarchically", which is available in the drop-down menu next to the filter box. In addition, you can use the "Filter" search bar to find a given task by name (only names are searchable). You can limit this to showing only user processes, or only system processes, active processes, or inactive ones, etc., which can be convenient for isolating specific tasks. This is where you view and manage all processes in the system.
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