puppet的refresh与refreshonly参数作用

eagleshi

　　- **refresh**
　　How to refresh this command.  By default, the exec is just
　　called again when it receives an event from another resource,
　　but this parameter allows you to define a different command
　　for refreshing.
　　- **refreshonly**
　　The command should only be run as a
　　refresh mechanism for when a dependent object is changed.  It only
　　makes sense to use this option when this command depends on some
　　other object; it is useful for triggering an action::
　　# Pull down the main aliases file
　　file { "/etc/aliases":
　　source => "puppet://server/module/aliases"
　　}
　　# Rebuild the database, but only when the file changes
　　exec { newaliases:
　　path => ["/usr/bin", "/usr/sbin"],
　　subscribe => File["/etc/aliases"],
　　refreshonly => true
　　}
　　Note that only ``subscribe`` and ``notify`` can trigger actions, not
　　``require``,
　　so it only makes sense to use ``refreshonly`` with ``subscribe`` or
　　``notify``.  Valid values are ``true``, ``false``.
　　refresh可能不太好理解，但refreshonly在pi命令中解释的比较清楚