test1.c

unix环境高级编程的源代码

#include    <signal.h>
#include    "ourhdr.h"

int
main(void)
{
    pid_t    pid;

    if ( (pid = fork()) < 0)
        err_sys("fork error");
    else if (pid != 0) {        /* parent */
        sleep(2);
        exit(2);                /* terminate with exit status 2 */
    }

                                /* first child */
    if ( (pid = fork()) < 0)
        err_sys("fork error");
    else if (pid != 0) {
        sleep(4);
        abort();                /* terminate with core dump */
    }

                                /* second child */
    if ( (pid = fork()) < 0)
        err_sys("fork error");
    else if (pid != 0) {
        execl("/usr/bin/dd", "dd", "if=/boot", "of=/dev/null", NULL);
        exit(7);                /* shouldn't get here */
    }

                                /* third child */
    if ( (pid = fork()) < 0)
        err_sys("fork error");
    else if (pid != 0) {
        sleep(8);
        exit(0);                /* normal exit */
    }

                                /* fourth child */
    sleep(6);
    kill(getpid(), SIGKILL);    /* terminate with signal, no core dump */
    exit(6);                    /* shouldn't get here */
}