Add the observed-shell plugin for observing and reporting with shell …

…commands

plugins/observed-shell/Gemfile

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+# A sample Gemfile
+source "https://rubygems.org"
+
+gem 'observed', :path => '../..'
+gem 'mixlib-shellout'

plugins/observed-shell/lib/observed/shell.rb

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+require 'mixlib/shellout'
+
+require 'observed/observer'
+require 'observed/reporter'
+
+module Observed
+  module Plugins
+  end
+end
+
+class Observed::Plugins::ShellObserver < Observed::Observer
+  plugin_name 'shell'
+
+  attribute :command
+
+  def observe
+    c = Mixlib::ShellOut.new(*command)
+    c.run_command
+    { command: command, stdout: c.stdout, stderr: c.stderr }
+  end
+end
+
+class Observed::Plugins::ShellReporter < Observed::Reporter
+  plugin_name 'shell'
+
+  attribute :command
+  attribute :input_key
+
+  def report(data, options)
+    if command.is_a? Proc
+      num_params = command.parameters.size
+      args = [data, options].take(num_params)
+      result = command.call *args
+      command_line = result
+    else
+      command_line = command
+    end
+    c = Mixlib::ShellOut.new(*command_line, input: data[get_attribute_value(:input_key)])
+    c.run_command
+    #logger.debug %Q|[observed-shell] ShellReporter executed the command "#{command_line}", captured stdout is "#{c.stdout}", captured stderr is #{c.stderr}"|
+    data
+  end
+end
+
+if __FILE__ == $0
+  require 'observed'
+
+  include Observed
+
+  test = (observe via: 'shell', with: { command: 'echo foo' } )
+    .then(report via: 'shell', with: { command: -> d { "growlnotify -m #{d[:stdout]}" } } )
+
+  test.now
+end