Linux C | fork的使用1

/*****************************************************
 *   > File Name: fork.c
 *   > Author: fly
 *   > Create Time: 2021-07-27  2/30  13:10:25 +0800
 *==================================================*/

#include 
#include 
#include 

int main(int argc, char* argv[])
{
    static int a = 0;

    printf("hello(%d). pid : %d, ppid: %d, a = %dn", 
            __LINE__, getpid(), getppid(), a);

    fork();
    fork();
    fork();

    a ++;
    printf("hello(%d). pid : %d, ppid: %d, a = %dn", 
            __LINE__, getpid(), getppid(), a);

    return 0;
}

[fly@fly-vm test]$ make fork
gcc -o fork fork.c -g -Wall[fly@fly-vm test]$ ./fork
hello(17). pid : 90746, ppid: 4636, a = 0
hello(25). pid : 90746, ppid: 4636, a = 1
hello(25). pid : 90747, ppid: 90746, a = 1
[fly@fly-vm test]$ hello(25). pid : 90749, ppid: 1, a = 1
hello(25). pid : 90748, ppid: 1, a = 1
hello(25). pid : 90750, ppid: 1, a = 1
hello(25). pid : 90753, ppid: 1, a = 1
hello(25). pid : 90752, ppid: 1, a = 1
hello(25). pid : 90751, ppid: 1, a = 1

[fly@fly-vm test]$