anchor.diff:  Artifact conditions are implemented using the
   link:https://code.google.com/p/objectfilter/[objectfilter] system that allows
   you to apply complex conditions to the attributes of an object. Artifacts can
  -apply conditions to any of the knowledgebase object attributes as defined in
  -knowledge_base.proto.
  +apply conditions to any of the Knowledge Base object attributes as defined in
  +link:https://code.google.com/p/grr/source/browse/proto/knowledge_base.proto[knowledge_base.proto].
   
   Since OS conditions are a very common constraint, this has been provided as a
   separate option "supported_os" to simplify syntax.  Under the hood, this:
  
positive.code: name: FirefoxHistory
  doc: Firefox places.sqlite files.
  collectors:
  - action: GetFiles
    args:
      path_list:
        - %%users.localappdata%%\Mozilla\Firefox\Profiles\*\places.sqlite
        - %%users.appdata%%\Mozilla\Firefox\Profiles\*\places.sqlite
    supported_os: [Windows]
  - action: GetFiles
    args:
      path_list: [%%users.homedir%%/Library/Application Support/Firefox/Profiles/*/places.sqlite]
    supported_os: [Darwin]
  - action: GetFiles
    args:
      path_list: ['%%users.homedir%%/.mozilla/firefox/*/places.sqlite']
    supported_os: [Linux]
  
negative.code: 
  --------------------------------------------------------------------------------
  collectors:
  - collector_type: COMMAND
    args:
      args: [-qa]
      cmd: /bin/rpm
  --------------------------------------------------------------------------------
  --------------------------------------------------------------------------------
  collectors:
  - collector_type: FILE
    args:
      path_list:
        - /root/.bashrc
  