思路是通過讀取/proc/uptime獲得系統啟動時長。
使用命令cat /proc/uptime
![這裡寫圖片描述](https://www.aspphp.online/bianchen/UploadFiles_4619/201701/2017010313455145.png "\")
通過man proc可以看到如下的信息：
喎?/kf/ware/vc/" target="_blank" class="keylink">vcHJvYy91cHRpbWWjulRoaXMgZmlsZSBjb250YWlucyB0d28gbnVtYmVyczogdGhlIHVwdGltZSBvZiB0aGUgc3lzdGVtIChzZWNvbmRzKSwgYW5kIHRoZSBhbW91bnQgb2YgdGltZSBzcGVudCBpbiBpZGxlIHByb2Nlc3MgKHNlY29uZHMpLjxiciAvPg0KtdrSu7j2ysfPtc2ztcTG9LavyrGzpKOstdq2/rj2ysfPtc2ztcS/1c/QyrG85KGjwb249rXEtaXOu7a8ysfD66GjPC9wPg0KPHByZSBjbGFzcz0="brush:java;">
#include
#include
#include
#include
struct timeval timeget(void)
{
struct timeval now;
unsigned char timestr[60] = {0};
unsigned char uptimestr[30] = {0};
unsigned char * dotaddr;
unsigned long second;
char error = 0;
FILE * timefile = NULL;
timefile = fopen("/proc/uptime", "r");
if(!timefile)
{
printf("[%s:line:%d] error opening '/proc/uptime'",__FILE__,__LINE__);
error = 1;
goto out;
}
if( (fread(timestr, sizeof(char), 60, timefile)) == 0 )
{
printf("[%s:line:%d] read '/proc/uptime' error",__FILE__,__LINE__);
error = 1;
goto out;
}
dotaddr = strchr(timestr, '.');
if((dotaddr - timestr + 2) < 30)
memcpy(uptimestr, timestr, dotaddr - timestr + 2);
else
{
printf("[%s:line:%d] uptime string is too long",__FILE__,__LINE__);
error = 1;
goto out;
}
uptimestr[dotaddr - timestr + 2] = '\0';
out:
if(error)
{
now.tv_sec = 0;
now.tv_usec = 0;
}
else
{
now.tv_sec = atol(uptimestr);
now.tv_usec = 0;
}
fclose(timefile);
return now;
}
int main()
{
struct timeval uptime;
uptime = timeget();
printf("uptime = %lu\n", uptime.tv_sec);
return 0;
}
運行結果：
