### 26.3 Process Identification

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 C Library, this is an `int`.

— Function: pid_t getpid (void)

> Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

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

— Function: pid_t getppid (void)

> Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

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