how to let hogs run only once,don't update every 3 seconds.

I want to print the percent of cpu for idle process in my c program.

  1. if pclose(ptr) is used (this means I just want hogs run only once).
    the program can’t print the message I want, just print the message
    about the broken pipe. (if use fd , the program run correctly. I know
    this problem occurs because hogs update message every 3 seconds . but
    I just want to print message only once.)

  2. if pclose(ptr) isn’t used (this means print the message all the
    time ) , the program can’t print the message immediately. I have
    tried fflush(stdout) and setvbuf为_IONBF,but still can’t solve it

    I don’t know how to slove this two programs. Thanks.

    char *cmd = “hogs | awk ‘{if($1==1)print$4}’”;
    // char *cmd = “hogs | awk ‘{print$4}’”;
    char buf [10];
    FILE *ptr;
    short idlecpu;
    if ((ptr = popen(cmd, “r”)) != NULL)
    if(fgets(buf,10, ptr) != NULL)
    if(fgets(buf,10, ptr) != NULL)
    printf(“idlecpu=%d \n”,idlecpu);
    printf("%s ",buf);