Cargo build

Executing cargo run will first compile your code including the build of an executable and then it will run it. In some cases you might only want do the compilation (and executable building) phase. You can do that by typing in:

cargo build

This will check if you already have an compiled binary in the target folder newer than your source code. If the binary does not exist or the source code is newer then it will build the binary. By default it will build in debug mode and will place the executable in the target/debug folder.

If the name of the crate is first-app as in the previous example then the cargo build command will generated the target/debug/first-app file on Linux and macOS and the target/debug/first-app.exe on MS Windows.

You can run this manually as

./target/debug/first-app

Release mode

Alternatively you could do the compilation and build the executable in release mode by providing the --release flag.

cargo build --release

This will probably take longer as it involves optimizations. You will probably do this rarely. This will create an executable in the target/release folder.

In both cases the filename of the executable is the value of the package.name field in the Cargo.toml file.

For the previous example it would generated the target/release/first-app file.

You can then run this as

./target/release/first-app

• build
• target
• --release