Run a command

Once you've added Command as a dependency, import Command in your Swift file:

import Command

To run a command, create an instance of CommandRunner, which conforms the mockable protocol CommandRunning:

let commandRunner = CommandRunner()

And then run your first command, for echo which outputs the string passed as an argument:

let output = try await commandRunner.run(
      arguments: ["echo", "command is amazing"]
    ).concatenatedString()

EXECUTABLE LOOKUP

When the executable is not an absolute path, the command runner will look for the executable in the system using the OS-specific search paths.

run returns a type AsyncThrowingStream<CommandEvent, any Error> which you can use to observe the output of the command. Since we are interested in the output of the command, we can use the function concatenatedString() defined on that type to get the output as a string.

By default, the comman will inherit the environment variables and the current working directory from the process that runs the command. You can customize them by using the arguments environment and workingDirectory of the run function.

let output = try await commandRunner.run(
      arguments: ["echo", "command is amazing"],
      environment: ["CUSTOM_ENV": "value"],
      workingDirectory: try AbsolutePath(validating: "/path/to/directory")
    ).concatenatedString()

STATIC INTERFACE

If you don't plan to mock the execution of commands, you can use the Command struct, which exposes the same interface as CommandRunner but as static functions:

let output = Command.run(arguments: ["echo", "command is amazing"]).concatenatedString()