LINUX下用C调用系统命令，并读取执行结果的代码

　　比如说，想看看某个IP是否通：

int   ping_ip(const char* ip)
{
    FILE *fstream = NULL;
    char buffer[1024];
    int found = -1;

    memset(buffer, 0, sizeof(buffer));  

    //只ping一次 
    sprintf(buffer, "ping -c 1 %s", ip);
    if (NULL == (fstream = popen(buffer,"r")))      
    {     
        return -1;      
    }   

    //读取执行结果
    while (NULL != fgets(buffer, sizeof(buffer), fstream)) 
    {  
        //LOG_INFO("%s", buffer);
        //包含特定字串，表示执行成功
        if (strstr(buffer, "bytes from") != NULL)
        {
            //找到了
            found = 0;
            break;
        }
    }

    pclose(fstream);    

    return found;     
}

实际测试中发现，fgets()有时会崩溃。