How to forking process in a way such that reaping the child isn't neccessary

Question

I seem to have a vague memory that some facility in Linux exists that allows one to fork() a process in such a way that the child is automatically reaped by the system without a zombie being created. What is this mechanism? Or is my memory just wrong?

Answer 1

The portable way to do this is to double-fork:

pid = fork();
if (pid>0) {
    int status;
    while (waitpid(pid, &status, 0) && !WIFEXITED(status) && !WIFSIGNALED(status));
    if (WIFSIGNALED(status) || WEXITSTATUS(status)) goto error;
} else if (!pid) {
    pid = fork();
    if (pid) _exit(pid<0);
    else {
        // do child work here
        _exit(0);
    }
} else goto error;