Various examples and tips for using the watch command in Linux

What is the Linux watch command?

The Linux watch command is a useful tool that repeatedly displays the result of a specific command at regular intervals.

For example, you can use it to monitor the system’s CPU and memory usage, detect changes in files, or check the network connection status.

The basic format of the watch command is as follows.

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watch [options] [command]

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There are various options, but the most commonly used ones are as follows.

• -n : Specifies the update interval in seconds. The default value is 2 seconds.
• -d : Highlights the parts that have changed compared to the previous result.
• -t : Does not display the time at the top.
• -c : Keeps the color.

Examples of using the watch command

Let’s look at some examples of how to use the watch command.

1. Monitoring system CPU and memory usage

If you want to monitor the system’s CPU and memory usage, you can use the watch command with the top command.

For example, if you enter the following, it will update the result of the top command every 1 second and highlight the changed parts.

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watch -n 1 -d top

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2. Detecting changes in files

If you want to detect changes in files, you can use the watch command with the ls command.

For example, if you enter the following, it will display the files in the current directory every 5 seconds and highlight the changed parts.

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watch -n 5 -d ls

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3. Checking network connection status

If you want to check the network connection status, you can use the watch command with the ping command.

For example, if you enter the following, it will output the ping result for a specific domain every 10 seconds and highlight the changed parts.

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watch -n 10 -d ping www.google.com

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Conclusion

The Linux watch command is a useful tool that repeatedly displays the result of a specific command at regular intervals.

You can use it to monitor the system status, detect changes in files, or check the network connection status.

You can adjust the update interval or the changed parts through options.
I personally use the watch command frequently. Especially, I use it a lot when working on servers.

I think the watch command is a simple but very effective tool. 

You should try it too!