orphan.c

unix环境高级编程的源代码

#include    <sys/types.h>
#include    <errno.h>
#include    <fcntl.h>
#include    <signal.h>
#include    "ourhdr.h"

static void    sig_hup(int);
static void    pr_ids(char *);

int
main(void)
{
    char    c;
    pid_t    pid;

    pr_ids("parent");
    if ( (pid = fork()) < 0)
        err_sys("fork error");

    else if (pid > 0) {    /* parent */
        sleep(5);        /* sleep to let child stop itself */
        exit(0);        /* then parent exits */

    } else {            /* child */
        pr_ids("child");
        signal(SIGHUP, sig_hup);    /* establish signal handler */
        kill(getpid(), SIGTSTP);    /* stop ourself */
        pr_ids("child");    /* this prints only if we're continued */
        if (read(0, &c, 1) != 1)
            printf("read error from control terminal, errno = %d\n", errno);
        exit(0);
    }
}

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

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