How to run Rust programs with 'cargo run' (with examples)

The cargo run command is an essential tool for Rust developers, as it efficiently combines the building and execution of a Rust project within one step. Cargo is Rust’s package manager and build system, and cargo run is particularly useful for compiling your code and running the resultant binary without having to type multiple, separate commands. It automatically detects the necessary dependencies, builds the project, and then executes it, thereby streamlining the development workflow.

Running the default binary target

Code:

cargo run

Motivation:

This is the simplest and most common use case. When you’re working on developing a Rust application and you want to quickly build and test your main project, cargo run is a straightforward command that compiles the whole project and runs the default binary target in one go.

Explanation:

• cargo is Rust’s package manager, which handles project creation, building, and compilation.
• run initiates the process of first compiling the project, then executing the main binary file it produces.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 1.23s
Running `target/debug/my_project`
Hello, Cargo!

Running a specified binary

Code:

cargo run --bin name

Motivation:

When a Rust project contains multiple binary targets, such as projects with different functionalities or tools, you might want to compile and execute just one specific binary. This command comes in handy to select and run the specific binary you’re interested in.

Explanation:

• --bin name specifies which binary target within the package should be built and run. The name corresponds to a binary target within the Cargo.toml file.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 0.78s
Running `target/debug/name`
Executing specific binary...

Running a specified example

Code:

cargo run --example name

Motivation:

Examples in Rust projects are small programs provided to demonstrate how parts of the library or application can be used in practice. This use case helps you run only the examples directory programs, which is beneficial for testing or learning.

Explanation:

• --example name indicates that you want to compile and run a project example with the given name, referring to programs located in the examples directory of your project.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 0.95s
Running `target/debug/examples/name`
Example output for <example>

Activating a space or comma-separated list of features

Code:

cargo run --features feature1 feature2

Motivation:

Features in Cargo are optional functionalities that can be turned on or off for compiling crates. When different builds require different features, this command allows you to specify which additional features should be enabled during the build.

Explanation:

• --features feature1 feature2 allows you to activate specific additional features during the compilation. Each feature name corresponds to an optional configuration in the project’s dependencies as defined in Cargo.toml.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 1.12s
Running `target/debug/my_project`
Running with feature set: feature1, feature2

Disabling the default features

Code:

cargo run --no-default-features

Motivation:

If a project comes with default features, and a specific build requires them to be turned off for testing or debugging purposes, this command is useful to compile the project without those default features.

Explanation:

• --no-default-features tells Cargo to refrain from activating all default features specified in the Cargo.toml, which is often used when you want to avoid certain default configurations.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 1.05s
Running `target/debug/my_project`
Running without any default features

Activating all available features

Code:

cargo run --all-features

Motivation:

When you want to ensure that all optional components of a crate work together properly, you can use this command to enable every single available feature. This can be particularly useful for comprehensive testing.

Explanation:

• --all-features activates every possible feature defined in the project’s Cargo.toml, which is an excellent way to ensure compatibility across all features.

Example output:

Compiling my_project v0.1.0
Finished dev [unoptimized + debuginfo] target(s) in 1.45s
Running `target/debug/my_project`
Running with all features activated

Running with the given profile

Code:

cargo run --profile name

Motivation:

When you have multiple profiles configured in your project, such as dev, release, or custom profiles, this command allows you to specifically run the project with a desired profile to suit different needs like debugging or performance analysis.

Explanation:

• --profile name specifies which profile to use during the build. Profiles are configurations that alter the build process for specific needs, such as setting optimization levels or debug information.

Example output:

Compiling my_project v0.1.0 (profile: name)
Finished profile [unoptimized + debuginfo] target(s) in 1.30s
Running `target/name/my_project`
Running with profile: <profile name>

Conclusion:

The cargo run command is a powerful utility within Rust’s ecosystem, simplifying the process of building and maintaining Rust projects by offering flexibility through various options and configurations. Whether you’re working with multiple binaries, examples, features, or profiles, cargo run can accommodate various development scenarios, streamlining tasks and enhancing productivity.