linux之sleep

linux中的sleep为库调用(library calls)，其声明文件为unistd.h。

unsigned int sleep(unsigned int seconds);

如果进程或者线程调用sleep请求的休眠的时间seconds过去，那么会返回0；如果休眠期间被信号中断，那么返回剩余的休眠时间。

 

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

void sig_handler(int num)
{
    printf("receive %d signal\n", num);
}

// 在休眠时间20s内，键入中断信号（ctrl+c)
int t_main()
{
    int time = 20;
    signal(SIGINT, sig_handler);
    printf("enter sleep\n");
    sleep(time);
    printf("sleep over\n");
    return 0;
}

/*

./xsleep
enter sleep
^Creceive 2 signal
sleep over

*/

int main()
{
    int time = 20;
    signal(SIGINT, sig_handler);
    printf("enter sleep\n");
    do{
        time = sleep(time);
    }while (time > 0);

    printf("sleep over\n");
    return 0;
}

/*

./xsleep
enter sleep
^Creceive 2 signal
^Creceive 2 signal
^Creceive 2 signal
^Creceive 2 signal
^Creceive 2 signal
^Creceive 2 signal
^Creceive 2 signal
sleep over

*/