How to Use ip link set Command on Multiple Interfaces with Bash Brace Expansion

Learn how to efficiently use the `ip link set` command to configure multiple network interfaces in Linux using Bash brace expansion.
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This video is based on the question https://stackoverflow.com/q/73947845/ asked by the user 'ss3071' ( https://stackoverflow.com/u/20122029/ ) and on the answer https://stackoverflow.com/a/73948095/ provided by the user 'Léa Gris' ( https://stackoverflow.com/u/7939871/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Streamline Your Network Configuration with Bash Brace Expansion

When managing multiple network interfaces in Linux, executing commands can become cumbersome. Typically, configuring each interface requires repetitive commands, which can be slow and prone to error. For instance, using the ip link set command, one might find themselves typing each command individually for each interface:

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This method is not only tedious but also inefficient, especially when scaling up to more interfaces. Fortunately, there is a way to leverage Bash's brace expansion feature to execute these commands in one step!

What is Brace Expansion?

Brace expansion is a feature in Bash that allows you to generate arbitrary strings. It can be particularly useful for commands that need to iterate over a range of values, making it easier to handle multiple instances at once.

Example of Brace Expansion

Using the example above, instead of typing out each individual command, you can utilize brace expansion like this:

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However, to directly execute this command, you'd face issues since the ip link set command does not accept brace expansion directly.

A More Efficient Approach

Step 1: Generating Interface Names

First, you need to generate a list of interface names. You can use the printf command for this:

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This command will produce the output:

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Step 2: Using xargs for Execution

Now that you have the interface names, the next step is to pipe this list into xargs, which executes commands based on the input:

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Explanation of the Command

printf 'ens1f%d\n' {0..3} generates the names of the interfaces.

The pipe | transfers this list to xargs.

-I{} tells xargs to replace {} with each item from the list generated by printf.

Finally, ip link set "{}" up is the command executed for each interface.

Summary

Using brace expansion along with printf and xargs, you can efficiently configure multiple network interfaces with a single command. Here’s the complete command again for quick reference:

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Utilizing this method not only saves time but also reduces the possibility of errors that come with repetitive command input. Embrace the power of Bash and make your network management tasks simpler and quicker!

Feel free to try this method the next time you need to configure multiple interfaces. Happy networking!