Linux Uptime Command

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In this tutorial, we will cover the uptime command.

As its name suggests, the main purpose of the uptime command is to show how long the system has been running. It will also display the current time, the number of logged in users, and the system load average.

How to Use the Uptime Command

The syntax for the uptime command is as follows:

uptime [OPTIONS]

To display the system uptime, invoke the command without any options:

uptime

The output will look something like below:

22:20:33 up 620 days, 22:37,  1 user,  load average: 0.03, 0.10, 0.10
  • 22:20:33 is the current system time.
  • up 620 days, 22:37 is the length of time the system has been up.
  • 1 user is the number of logged in users.
  • load average: 0.03, 0.10, 0.10 are system load averages for the past 1, 5, and 15 minutes.

The load average on Linux can be a little confusing. Unlike other operating systems that shows CPU load averages, Linux is showing system load averages.

System load average measurement of the number of jobs that are currently running or waiting for disk I/O. It basically tells you how busy your system has been over the given interval.

If the load averages are 0.0, then the system is mostly idle. If the load average for the past 1 minute is higher than the 5 or 15-minute averages, then the load is increasing, otherwise, the load is decreasing. The load average increases due to higher CPU consumption, disk workload.

To better understand the Linux load averages check the Brendan Gregg’s post Linux Load Averages: Solving the Mystery.

Uptime Command Options

The uptime command accepts only a few options that are rarely used.

The -p, --pretty option tells uptime to display the output in a pretty format:

uptime -p

The output will show only how long the system has been running:

up 1 year, 36 weeks, 4 days, 23 hours, 15 minutes

The -s, --since option shows the date and time since the system is up:

uptime -s
2017-09-01 23:43:32

Other two options are:

  • -h, --help - Display a help message and exit.
  • -V, --version - Shows the version information and exit.

Conclusion

The uptime command is easy to remember and gives you information about the current time, online users, how long your system has been up and running and the system load average.