Uptime command introduction

As the name suggests, the uptime command tells you how long the system has been up (running). This is the syntax:

uptime [options]

The man page of this tool says this:

uptime会在一行中显示下列信息：当前时间、系统运行了多久时间、当前登录的用户有多少，以及前 1、5 和 15 分钟系统的平均负载。

The following cases in question and answer format should give you a better understanding of the uptime command.

The basic usage of uptime is very simple - just enter the command name and press Enter. This is the output:

Here, the first item is the current time, up indicates that the system is running, 5:53 is the total time of system startup, and the last is the load information of the system. If you want to dig deeper, here's what the uptime man page says about the last piece of information:

系统负载是处于可运行runnable或不可中断uninterruptable状态的进程的平均数。可运行状态的进程要么正在使用 CPU 要么在等待使用 CPU。 不可中断状态的进程则正在等待某些 I/O 访问，例如等待磁盘 IO。
有三个时间间隔的平均值。负载均值的意义根据系统中 CPU 的数量不同而不同，负载为 1 对于一个只有单 CPU 的系统来说意味着负载满了，而对于一个拥有 4 CPU 的系统来说则意味着 75% 的时间里都是空闲的。

If you just want to know how long the system has been running, and want to display it in a more user-friendly format, you can use the -p option

uptime -p

This is the output:

You can also specify uptme to display the time and date when the system starts running. The method is to use the -s command option.

uptime -s

This is the output:

-V gets version information, -h gets help information.

uptime -V
uptime -h

As you can see, the uptime command is easy to understand and easy to use. It doesn't offer a lot of functionality (and few command options). All its functions have been covered here. So just practice these options and you will be able to use it in your daily work. If necessary, you can also check its man page[1].

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