Class RVM::Shell::AbstractWrapper
In: lib/rvm/shell/abstract_wrapper.rb
Parent: Object

Provides the most common functionality expected of a shell wrapper. Namely, implements general utility methods and tools to extract output from a given command but doesn‘t actually run any commands itself, leaving that up to concrete implementations.

Usage

Commands are run inside of a shell (usually bash) and can either be exectuted in two situations (each with wrapper methods available) - silently or verbosely.

Silent commands (via run_silently and run_command) do exactly as they say - that can modify the environment etc but anything they print (to stdout or stderr) will be discarded.

Verbose commands will run the command and then print the command epilog (which contains the output stastus and the current env in yaml format). This allows us to not only capture all output but to also return the exit status and environment variables in a way that makes persisted shell sessions possible.

Under the hood, run and run_silently are the preferred ways of invoking commands - if passed a single command, they‘ll run it as is (much like system in ruby) but when given multiple arguments anything after the first will be escaped (e.g. you can hence pass code etc). run will also parse the results of this epilog into a usable RVM::Shell::Result object.

run_command and run_command_silently do the actual hard work for these behind the scenes, running a string as the shell command. Hence, these two commands are what must be implemented in non-abstract wrappers.

For an example of the shell wrapper functionality in action, see RVM::Environment which delegates most of the work to a shell wrapper.

Methods

Included Modules

RVM::Shell::Utility

Constants

COMMAND_EPILOG_START = "---------------RVM-RESULTS-START---------------"   Used the mark the end of a commands output and the start of the rvm env.
COMMAND_EPILOG_END = "----------------RVM-RESULTS-END----------------"   Used to mark the end of the commands epilog.
WRAPPER_LOCATION = File.expand_path('./shell_wrapper.sh', File.dirname(__FILE__))   The location of the shell file with the epilog function definition.

Attributes

shell_executable  [R]  Defines the shell exectuable.

Public Class methods

Initializes a new shell wrapper, including setting the default setup block. Implementations must override this method but must ensure that they call super to perform the expected standard setup.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 52
      def initialize(sh = 'bash', &setup_block)
        setup &setup_block
        @shell_executable = sh
      end

Public Instance methods

Returns a given environment variables’ value.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 96
      def [](var_name)
        run(:true)[var_name]
      end

Runs the gives command (with optional arguments), returning an RVM::Shell::Result object, including stdout / stderr streams. Under the hood, uses run_command to actually process it all.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 69
      def run(command, *arguments)
        expanded_command = build_cli_call(command, arguments)
        status, out, err = run_command(expanded_command)
        Result.new(expanded_command, status, out, err)
      end

Given a command, it will execute it in the current wrapper and once done, will return:

  • the hash from the epilog output.
  • a string representing stdout.
  • a string representing stderr.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 86
      def run_command(full_command)
        raise NotImplementedError.new("run_command is only available in concrete implementations")
      end

Like run_command, but doesn‘t care about output.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 91
      def run_command_silently(full_command)
        raise NotImplementedError.new("run_command_silently is only available in concrete implementations")
      end

Wrapper around run_command_silently that correctly escapes arguments. Essentially, run but using run_command_silently.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 77
      def run_silently(command, *arguments)
        run_command_silently build_cli_call(command, arguments)
      end

Defines a setup block to be run when initiating a wrapper session. Usually used for doing things such as sourcing the rvm file. Please note that the wrapper file is automatically source.

The setup block should be automatically run by wrapper implementations.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 62
      def setup(&blk)
        @setup_block = blk
      end

Protected Instance methods

Checks whether the given command includes a epilog, marked by epilog start and end lines.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 126
      def command_complete?(c)
        start_index, end_index = c.index(COMMAND_EPILOG_START), c.index(COMMAND_EPILOG_END)
        start_index && end_index && start_index < end_index
      end

When called, will use the current environment to source the wrapper scripts as well as invoking the current setup block. as defined on initialization / via setup.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 104
      def invoke_setup!
        source_command_wrapper
        @setup_block.call(self) if @setup_block
      end

Takes a raw string from a processes STDIO and returns three things:

  1. The actual stdout, minus epilogue.
  2. YAML output of the process results.
  3. Any left over from the STDIO text.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 135
      def raw_stdout_to_parts(c)
        raise IncompleteCommandError if !command_complete?(c)
        before, after = c.split(COMMAND_EPILOG_START, 2)
        epilog, after = after.split(COMMAND_EPILOG_END, 2)
        return before, YAML.load(epilog.strip), after
      end

Wraps a command in a way that it prints no output.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 120
      def silent_command(command)
        "{ #{command}; } >/dev/null 2>&1"
      end

Uses run_silently to source the wrapper file.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 110
      def source_command_wrapper
        run_silently :source, WRAPPER_LOCATION
      end

Returns a command followed by the call to show the epilog.

[Source]

# File lib/rvm/shell/abstract_wrapper.rb, line 115
      def wrapped_command(command)
        "#{command}; __rvm_show_command_epilog"
      end

[Validate]