1.uptime命令
root@localhost:/var/log# uptime 06:44:12 up 7 days, 21:44, 1 user, load average: 0.01, 0.03, 0.00
2.查看/proc/uptime文件
root@localhost:/var/log# cat /proc/uptime 683113.07 682104.86
2-1.计算系统启动时间（date命令）
root@localhost:/var/log# date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"
2016-10-25 09:00:01
2-2.计算系统运行时间
root@localhost:/var/log# 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\n",run_days,run_hour,run_minute,run_second)}'
系统已运行：7天21时51分31秒
3.who 命令查看
root@localhost:/var/log# who -b
系统引导 2016-10-25 08:59
root@localhost:/var/log# who -r
运行级别 5 2016-10-25 08:59
4.last reboot命令
root@localhost:/var/log# last reboot reboot system boot 2.6.32-042stab11 Tue Oct 25 08:59 - 06:54 (7+21:55) reboot system boot 2.6.32-042stab11 Mon Oct 24 15:04 - 08:59 (17:55) reboot system boot 2.6.32-042stab11 Mon Oct 24 15:00 - 15:04 (00:03) reboot system boot 2.6.32-042stab11 Mon Oct 24 08:10 - 15:00 (06:50) reboot system boot 2.6.32-042stab11 Mon Oct 24 07:58 - 08:10 (00:12) reboot system boot 2.6.32-042stab11 Mon Oct 24 07:28 - 07:58 (00:29) reboot system boot 2.6.32-042stab11 Sat Oct 22 07:56 - 07:27 (1+23:31) reboot system boot 2.6.32-042stab11 Sat Oct 22 07:37 - 07:56 (00:18) root@localhost:/var/log# last reboot | head -1 reboot system boot 2.6.32-042stab11 Tue Oct 25 08:59 - 06:56 (7+21:56)
5.top命令
top - 06:57:17 up 7 days, 21:57, 1 user, load average: 0.00, 0.00, 0.00 Tasks: 24 total, 1 running, 23 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 1048576 total, 954152 free, 38432 used, 55992 buff/cache KiB Swap: 131072 total, 121632 free, 9440 used. 928059 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 365 root 20 0 39020 16152 1488 S 0.7 1.5 73:09.13 server_linux_am 1 root 20 0 42292 3484 1384 S 0.0 0.3 0:24.71 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd/386442 3 root 20 0 0 0 0 S 0.0 0.0 0:00.22 khelper/386442 69 root 20 0 41432 460 456 S 0.0 0.0 0:00.00 systemd-udevd 70 root 20 0 92600 7100 6984 S 0.0 0.7 0:07.27 systemd-journal 102 dbus 20 0 26416 864 680 S 0.0 0.1 0:09.80 dbus-daemon 107 root 20 0 26352 1000 848 S 0.0 0.1 0:07.24 systemd-logind ......
6.w命令
root@localhost:/var/log# w 07:00:33 up 7 days, 22:00, 1 user, load average: 0.07, 0.03, 0.00 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT frost pts/0 124.65.123.238 06:28 0.00s 0.09s 0.01s sshd: 123 [priv]