What are the various IDs in UNIX processes?

A process ID is a unique integer that UNIX uses to identify a certain process.

The process executes to initiate other processes is called parent process and its ID is defined as PPID (Parent Process ID).

* getppid() retrieves the Parent Process ID?

Every process is associated with a specific user and is called the owner of the process. The owner has all the privileges over the process. The owner is also the user who executes the process.

Identification for a user is User ID. The process also associated with Effective User ID which determines the access privileges to accessing resources like files.

* getpid() retrieves the Process ID

* getuid() retrieves the User ID

* geteuid() retrieves the Effective User ID