UNIX Computing Security/System processes

System processes of UNIX consist of those processes that are not user services or user processes. One of the most known is init.

Init

The parent of all processes. init will take ownership of orphaned processes. Process ID is almost always 1.

Viewing processes

For example, a user may list the status of his or her processes using the ps command, thus:

 $ ps -f
 UID         PID  PPID  C     STIME TTY      TIME CMD
 john_doe  15265 15254  0  11:18:13 pts/5   00:00 -sh
 john_doe  11407 15265  1  13:52:09 pts/5   00:00 ps -f

The user with the account name john_doe is the owner of the two processes with process identifiers 15265 and 11407. That user can send signals to those two processes using the kill command. However the system can prevent that user from using the kill command on processes he does not own.