What are various IDs associated with a process?
Unix identifies each process with a unique integer known as ProcessID. The process that implements the request for creation of a process is known as the 'parent process' whose PID is 'Parent Process ID'. Every process is associated with a particular user called the 'owner' who has privileges over the process. The identification for the user is 'UserID'. Owner is the user who implements the process. Process also has 'Effective User ID' which verifies the access privileges for accessing resources like files.
getpid() -process id
getppid() -parent process id
getuid() -user id
geteuid() -effective user id