getpid () pit_t

[oj2wbRfi]

This a small progam to print the process ID
I got this result


The process id: 165949

which process is this ? As I know is the getpid() is to return the ID of the calling process, is that mean the process which the system called or just random process?

  #include <stdio.h>
    #include <sys/types.h>
    #include <unistd.h>
    
    int main(void)
    {
        pid_t process_id;
   
   
       process_id = getpid();
     
       printf("ID is : %d\n",process_id);
  
  
       return 0;
   }

[salem c]

> which process is this ?
It's the process ID of the thing you're running
- starts at main
- calls printf
- ends at return 0
All that is running with the pid of what you see on screen.

[oj2wbRfi]

so is that mean that to get :

1- the child process or the current process we use

process_id = getpid();

and

2- the parnet process of the current process is p_process_id = getppid();

or the current process and the child process is not the same !

[salem c]

I dunno where you're getting the idea of child within the file itself, when it's not the thing actually creating any processes.

$ cat foo.c
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

int main(void)
{
    pid_t process_id, parent_pid;
    process_id = getpid();
    parent_pid = getppid();
    printf("My ID is : %d\n",process_id);
    printf("My parent is %d\n",parent_pid);
    return 0;
}

$ gcc foo.c
$ ./a.out 
My ID is : 17429
My parent is 16267

$ echo $$
16267

Notice anything interesting here?

$$ is the shell variable indicating the process ID of itself, which will naturally become the parent process ID of anything the shell creates (like the above mentioned program).
https://www.tutorialspoint.com/unix/unix-special-variables.htm