#
View Source Mix.Shell behaviour (Mix v1.15.7)

Defines `Mix.Shell` contract.

# Summary

## Callbacks

cmd(command)

Executes the given command and returns its exit status.

cmd(command, options)

Executes the given command and returns its exit status.

error(message)

Prints the given ANSI error to the shell.

info(message)

Prints the given ANSI message to the shell.

print_app()

Prints the current application to the shell if it was not printed yet.

prompt(message)

Prompts the user for input.

yes?(message)

Prompts the user for confirmation.

yes?(message, options)

Prompts the user for confirmation.

## Functions

cmd(command, options \\ [], callback)

Executes the given `command` as a shell command and invokes the `callback` for the streamed response.

printable_app_name()

Returns the printable app name.

# Callbacks

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# cmd(command)

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    @callback cmd(command :: String.t()) :: integer()

Executes the given command and returns its exit status.

Shortcut for `cmd/2` with empty options.

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# cmd(command, options)

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    @callback cmd(command :: String.t(), options :: keyword()) :: integer()

Executes the given command and returns its exit status.

## Options

This callback should support the following options:

- `:print_app` - when `false`, does not print the app name when the command outputs something

- `:stderr_to_stdout` - when `false`, does not redirect stderr to stdout

- `:quiet` - when `true`, do not print the command output

- `:env` - environment options to the executed command

- `:cd` - (since v1.11.0) the directory to run the command in

All the built-in shells support these.

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# error(message)

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    @callback error(message :: IO.ANSI.ansidata()) :: :ok

Prints the given ANSI error to the shell.

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# info(message)

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    @callback info(message :: IO.ANSI.ansidata()) :: :ok

Prints the given ANSI message to the shell.

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# print_app()

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    @callback print_app() :: :ok

Prints the current application to the shell if it was not printed yet.

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# prompt(message)

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    @callback prompt(message :: binary()) :: binary()

Prompts the user for input.

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# yes?(message)

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    @callback yes?(message :: binary()) :: boolean()

Prompts the user for confirmation.

Shortcut for `yes?/2` with empty options.

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# yes?(message, options)

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    @callback yes?(message :: binary(), options :: keyword()) :: boolean()

Prompts the user for confirmation.

## Options

- `:default` - `:yes` or `:no` (the default is `:yes`)

# Functions

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# cmd(command, options \\ [], callback)

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    @spec cmd(String.t(), keyword(), (binary() -> term())) ::
      exit_status :: non_neg_integer()

Executes the given `command` as a shell command and invokes the `callback` for the streamed response.

This is most commonly used by shell implementations but can also be invoked directly.

`callback` takes the output data of the command. Its return value is ignored.

## Options

- `:cd` - (since v1.11.0) the directory to run the command in

- `:stderr_to_stdout` - redirects stderr to stdout, defaults to true

- `:env` - a list of environment variables, defaults to `[]`

- `:quiet` - overrides the callback to no-op

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# printable_app_name()

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    @spec printable_app_name() :: atom() | nil

Returns the printable app name.

This function returns the current application name, but only if the application name should be printed.

Calling this function automatically toggles its value to `false` until the current project is re-entered. The goal is to avoid printing the application name multiple times.