On Windows, open Task Manager and check the Performance tab for "Up time" or use Command Prompt with "net stats workstation" or PowerShell with "(Get-CimInstance Win32_OperatingSystem).LastBootUpTime" to get the last boot time; 2. On macOS, run "uptime" in Terminal to see how long the system has been running or use "sysctl kern.boottime" for exact boot time; 3. On Linux, use "uptime" to display system runtime or "who -b" or "timedatectl status" for precise boot timestamp; checking uptime helps assess system stability, confirm reboots, and identify maintenance needs, making it a quick and valuable diagnostic step.

Checking the uptime of a computer — that is, how long it has been running since the last reboot — is a simple way to monitor system stability, performance, or maintenance needs. The method varies slightly depending on your operating system.

On Windows

There are a few easy ways to check uptime on a Windows machine:

1. Using Task Manager:

• Press Ctrl Shift Esc to open Task Manager.
• Go to the Performance tab.
• Select CPU from the left panel.
• Look for "Up time" at the bottom-right corner. It shows days, hours, minutes, and seconds since the last reboot.

2. Using Command Prompt or PowerShell:

• Open Command Prompt or PowerShell.
• Type the following command and press Enter:

  net stats workstation

  Look for the line that says "Statistics since" — this shows when the system was last started.

  

Alternatively, in PowerShell, you can run:

(Get-CimInstance Win32_OperatingSystem).LastBootUpTime

This returns the exact date and time the system was last booted.

On macOS

macOS provides a quick way to check uptime via the terminal:

Using Terminal:

• Open Terminal (you can find it via Spotlight with Cmd Space and typing "Terminal").
• Type:

  uptime

• Press Enter.

The output shows:

• How long the system has been running.
• Current time.
• Number of users.
• System load averages over the last 1, 5, and 15 minutes.

For example:

10:30  up 2 days,  5:12, 2 users, load averages: 1.12 1.08 1.05

You can also use:

sysctl kern.boottime

This gives you the exact boot time in a more technical format.

On Linux

Most Linux distributions support the uptime command:

Using the terminal:

• Open a terminal window.
• Type:

  uptime

• Press Enter.

This displays:

• Current time.
• How long the system has been running.
• Number of users.
• Load averages.

For more detailed boot time information, use:

who -b

This shows the exact time of the last system boot.

Alternatively:

timedatectl status

Look for the line that says "System boot" — it includes the precise boot timestamp.

Why Uptime Matters

While a long uptime might seem like a sign of stability, it can also mean the system hasn’t received recent updates or patches. On servers, uptime is closely monitored, but on personal computers, regular reboots help apply updates and clear temporary issues.

Checking uptime is quick and useful for troubleshooting performance issues or verifying if a recent reboot actually occurred.

Basically, just open a terminal or system monitor and run one command — it's fast and informative.

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