GNU C Library (libc) Programming Guide

The pid_t data type represents process IDs. You can get the process ID of a process by calling getpid. The function getppid returns the process ID of the parent of the current process (this is also known as the parent process ID). Your program should include the header files unistd.h and sys/types.h to use these functions.

— Data Type: pid_t

The pid_t data type is a signed integer type which is capable of representing a process ID. In the GNU library, this is an int.

— Function: pid_t getpid (void)

The getpid function returns the process ID of the current process.

— Function: pid_t getppid (void)

The getppid function returns the process ID of the parent of the current process.