wait4プログラム

wait3に引数pidが増えただけです。

#include < sys/types.h >
#include < sys/time.h >
#include < sys/resource.h >
#include < sys/wait.h >

#include < unistd.h >
#include < stdio.h >

int
main()
{
    int status;
    pid_t pid;
    struct rusage usage;
    
    if ((pid = fork()) < 0){
        perror("fork");
        return 1;
    } else if (pid == 0){
        write(1, "chlid process\n", 14);
        _exit(12);
    }
    write(1, "parent process\n", 15);
    
    if ((pid = wait4(pid, status, 0, &usage)) < 0){
        perror("wait4");
        return 1;
    }
    if(WIFEXITED(status)){
        printf(
        "pid = %d exited with status = %d\n",
               (int)pid, WEXITSTATUS(status));
    }
    
    printf(
    "user time = %ld.%06ld\n"
    "system time = %ld.%06ld\n",
    usage.ru_utime.tv_sec, usage.ru_utime.tv_usec,
           usage.ru_stime.tv_sec, usage.ru_stime.tv_usec);
    return 0;
}