Process ID

PID and PPID

PID (Process ID): A unique identifier assigned by the operating system to each running process.
PPID (Parent Process ID): The process ID of the parent process, i.e., the process that spawned the current process.

Methods

getpid(): Returns the process ID of the calling process.
getppid(): Returns the parent process ID of the calling process.

Example in C

#include <stdio.h>
#include <unistd.h>

int main() {
    pid_t pid = getpid();   // Get current process ID
    pid_t ppid = getppid(); // Get parent process ID

    printf("PID: %d\n", pid);
    printf("PPID: %d\n", ppid);

    return 0;
}

Key Points

Use getpid() to retrieve the current process ID.
Use getppid() to retrieve the parent process ID.