Linux中获取系统运行时间的多种方法详解

#!/bin/sh
 
uptime_seconds=$(cat /proc/uptime | cut -d. -f1)
 
days=$((uptime_seconds / (24 * 60 * 60)))
uptime_seconds=$((uptime_seconds % (24 * 60 * 60)))
hours=$((uptime_seconds / (60 * 60)
uptime_seconds=$((uptime_seconds % (60 * 60)))
minutes=$((uptime_seconds / 60))
seconds=$((uptime_seconds % 60))
 
echo "系统运行时间: $days 天 $hours 小时 $minutes 分钟 $seconds 秒"

#include <stdio.h>
#include <stdlib.h>
 
void get_run_time(char *time)
{
    FILE *fp;
    double uptime_seconds;
    int days, hours, minutes, seconds;
 
    // 打开 /proc/uptime 文件
    fp = fopen("/proc/uptime", "r");
    if (fp == NULL) {
        perror("无法打开 /proc/uptime 文件");
        return;
    }
 
    // 读取系统运行的总秒数
    fscanf(fp, "%lf", &uptime_seconds);
    fclose(fp);
 
    // 计算天、时、分、秒
    days = (int)uptime_seconds / (24 * 60 * 60);
    uptime_seconds = (int)uptime_seconds % (24 * 60 * 60);
    hours = (int)uptime_seconds / (60 * 60);
    uptime_seconds = (int)uptime_seconds % (60 * 60);
    minutes = (int)uptime_seconds / 60;
    seconds = (int)uptime_seconds % 60;
 
    if (days > 0) {
        sprintf(time, "%dday%dh%dm%ds", days, hours, minutes, seconds);
    } else if(hours > 0) {
        sprintf(time, "%dh%dm%ds", hours, minutes, seconds);
    } else if(minutes > 0) {
        sprintf(time, "%dm%ds", minutes, seconds);
    } else {
        sprintf(time, "%ds", seconds);
    }
}
 
int main(void)
{
    char run_time[32] = {0};
    get_run_time(run_time);
    printf("Time：%s\r\n", run_time);
}

uptime

systemctl list-timers

cat /proc/uptime

echo "scale=2; 887563.92 / 60 / 60 / 24" | bc

grep -i "boot" /var/log/messages

journalctl --list-boots

last | grep reboot