Chapter 3. The rustfmt formatting tool


With the rustfmt formatting tool, you can automatically format the source code of your Rust programs. You can use rusftmt either as a standalone tool or with Cargo.

For further details, see the rustfmt help pages displayed by the rustfmt --help command.

3.1. Installing rustfmt

Complete the following steps to install the rustfmt formatting tool.

Procedure

  • Install the rustfmt package:

    • On RHEL 8, enter:

      # yum install rustfmt
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    • On RHEL 9 and 10, enter:

      # dnf install rustfmt
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3.2. Using rustfmt as a standalone tool

Use rustfmt as a standalone tool to format a Rust source file and all its dependencies. As an alternative, use rustfmt with the Cargo build tool. For more information, see Using rustfmt with the Cargo build tool.

Prerequisites

Procedure

  • Format the Rust source code:

    $ rustfmt <source-file>
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    Replace <source_file> with the name of your source file. Alternatively, you can replace <source_file> with standard input. The rustfmt utility then provides its output in standard output.

    Important

    By default, rustfmt modifies the affected files without displaying details or creating backups. To display details and create backups, run rustfmt with the --write-mode option.

3.3. Using rustfmt with the Cargo build tool

Use the rustfmt tool with Cargo to format a Rust source file and all its dependencies. As an alternative, use rustfmt as a standalone tool. For more information, see Using rustfmt as a standalone tool.

Prerequisites

Procedure

  1. Optional: To change the rustfmt formatting options, create rustfmt.toml configuration file in the project directory and add your configurations to the file.
  2. Format the Rust source code:

    $ cargo fmt
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