1.uptime命令  例子显示已启动13天 当前用户一个

[root@localhost-live version-build-related]# uptime
:: up days, :, user, load average: 1.38, 1.55, 1.56

2.查看/proc/uptime文件计算系统启动时间
[root@localhost-live version-build-related]# cat /proc/uptime
1153389.58 3457597.11    运用系统工具date算出系统启动时间

[root@localhost-live version-build-related]#  date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"
2018-03-13 10:57:04

3.查看/proc/uptime文件计算系统运行时间

[root@localhost-live version-build-related]# cat /proc/uptime| awk -F. '{run_days=$1 / 86400;run_hour=($1 % 86400)/3600;run_minute=($1 % 3600)/60;run_second=$1 % 60;printf("系 统已运行:%d天%d时%d分%d秒",run_days,run_hour,run_minute,run_second)}'
系统已运行:13天8时26分27秒

4、查看系统安装时间

tune2fs -l /dev/sda1 | grep create

[root@localhost-live version-build-related]# tune2fs -l /dev/sda1 | grep create
Filesystem created: Mon Mar ::
05-03 22:51