进程关系

屏幕快照 2020-07-02 下午12.18.52.png 屏幕快照 2020-07-02 下午12.19.39.png 屏幕快照 2020-07-02 下午12.20.07.png 屏幕快照 2020-07-02 下午12.20.31.png 屏幕快照 2020-07-02 下午12.21.14.png 屏幕快照 2020-07-02 下午12.54.51.png

#include <apue.h>
#include <error.h>
#include <errno.h>

static void sig_hup(int signo) {
    printf("SIGHUP received, pid = %ld\n", (long) getpid());
}

static void pr_ids(char *name) {
    printf("%s: pid = %ld, ppid = %ld, pgrp = %ld, tpgrp = %ld\n", name, (long) getpid(), (long) getppid(),
           (long) getpgrp(), (long) tcgetpgrp(STDIN_FILENO));
    fflush(stdout);
}

int main(void) {
    char c;
    pid_t pid;
    pr_ids("parent");
    if ((pid = fork()) < 0)
        err_sys("fork failed");
    else if (pid > 0) {
        sleep(5);
    } else {
        pr_ids("child");
        signal(SIGHUP, sig_hup);
        kill(getpid(), SIGTSTP);
        pr_ids("child");
        if (read(STDIN_FILENO, &c, 1) != 1)
            printf("read error %d on controlling TTY\n", errno);
    }
    exit(0);
}

屏幕快照 2020-07-02 下午1.58.15.png