uptime — Boot time and load

💬 "uptime command"

The uptime command shows uptime and load average in a single line. It is a good first command for inspection.

You can immediately see reboot status and load trends (1/5/15 minutes).

• Current time: the time when the command was executed.
• up: elapsed time since the last boot.
• users: the number of logged-in users.
• load average: the average load over the last 1, 5, and 15 minutes.

Commonly Used Options

Three Essential Command Combinations

• uptime — check uptime and load in one line
• uptime -s — check the last boot time
• uptime && nproc — compare load with the number of cores

💬 "Show me an example of applying this to multiple servers at once"

The following is a step-by-step summary of common situations encountered on production servers.

Step 1 · Check for Reboots

If uptime is shorter than expected, check for a reboot.

uptime -s

Step 2 · Check Load

Compare the load with the number of cores.

uptime && nproc

Step 3 · Trace the Cause

If the load is high, check the top processes.

top -o %CPU -b -n 1 | head -12

How It Is Used in Practice

1. Check for Unauthorized Reboots

Situation — You need to check when the server was rebooted.

uptime -s

Result — The last boot time is printed so you can compare it with maintenance records.

Point — You can view the entire boot history with journalctl --list-boots.

2. Assess Load Trends

Situation — Response is slow, but the CPU looks idle.

uptime && nproc && free -h

Result — If the 15-minute load is high and swap usage is large, suspect a memory/I/O problem.

Point — Do not judge by load alone; check CPU, memory, and I/O together.

Important Notes

• Load average is based on the number of running/waiting processes, not the number of requests.
• The same load value has different implications depending on the number of cores.
• In virtualized environments, host load can be reflected in guests.

Actual Output

This is the result of checking uptime/load, boot time, and the number of cores.

!uptime command output: uptime and load

Production server

Source (HTML): https://games.aidebatehub.com/programs/linux/services/uptime.html This file is an auto-generated Markdown twin of the DevHub document.