Why getppid() from the child return 1

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Because parent process is finished by the time the child asks for its parent's pid.

When a process finishes, all its children are reassigned as children of the init process, which pid is 1.

Try using wait() in parent's code to wait for the child to execute. It should then work as you expect.

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user567879
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Updated on September 18, 2022

Comments

  • user567879
    user567879 over 1 year

    I was running the program

    #include<stdio.h>
    #include <unistd.h>
    main()
    {
        pid_t pid, ppid;
        printf("Hello World1\n");
        pid=fork();
        if(pid==0)
        {
            printf("I am the child\n");
            printf("The PID of child is %d\n",getpid());
            printf("The PID of parent of child is %d\n",getppid());
        }
        else
        {
            printf("I am the parent\n");
            printf("The PID of parent is %d\n",getpid());
            printf("The PID of parent of parent is %d\n",getppid());        
        }
    }
    

    THe output I got was.

    $ ./a.out 
    Hello World1
    I am the parent
    The PID of parent is 3071
    The PID of parent of parent is 2456
    I am the child
    The PID of child is 3072
    The PID of parent of child is 1
    

    I couldnt understand the line

    The PID of parent of child is 1

    It should have been 3071?