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Execute CLI utilities

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README.rdoc

Executioner

Executioner is a module you can include in your classes to run binaries from your Ruby code.

class Recording
  include Executioner
  executable :lame, :switch_stdout_and_stderr => true

  def transcode
    lame("--abr 128 -m s #{filename} #{filename_as_mp3}")
  end
end

Specifying a binary

By default Executioner looks in Executioner::SEARCH_PATHS for the binary.

executable :sh

If the binary is installed in a specific location you might want to specify the entire path to the executable.

executable :import, :path => App.root_path + 'scripts/import'

And when you need to specify environment variables for the executable you can do so as well.

executable :migrate, :env => { 'ENV' => 'PRODUCTION' }

If you need more elaborate rules to pick a specific path for a binary you can specify a block that selects the right one.

executable :gcc, :select_if => lambda { |path|
  File.ftype(path) != 'link' and !path.start_with?('/opt')
}

Reading output

Executioner reads either stdout or stderr and returns it from the call to the binary. In the example presented above a call to lame would return the entire output to stderr produced by Lame.

lame("--work") # => "lame: unrecognized option --work"

Exceptions

A call to a binary raises a ProcessError when the output stream is empty and there is stuff in the error stream. An ExecutableNotFoundError is raised when the executable can't be found in the path.

Queues

Executioner uses popen3 to run a subprocess with the executable. Starting a process takes some time so if you're running lots of short commands you can probably win some time by executing them from a queue.

executable :ppane, :use_queue => true

Now calling ls will queue the command instead of executing it. You can execute the entire queue by calling execute_queued.

ppane('add ~/Code/project')
ppane('register')
execute_queued

Logging

If you want to log everything Executioner does, you can assign a logger instance to Executioner.logger.

Executioner.logger = Rails.logger
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