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You can also use file=- to indicate that STDOUT should be used for export or STDIN be used for update/creation. The act=update operation doesn't create new nodes, and it replaces the whole set of node configuration settings with your new configuration input. So, if a property is not set, it will disappear. For change only one property, the operation "set" is more accurate.
Creation of Nodes
The creation of nodes requires you to use a template (shown below) instead of using a command line argument; this is because NMIS requires numerous node properties to be set up correctly making it easy to miss some when operating via command line arguments. Node creation is triggered by the argument act=create, which behaves mostly like act=update, except that it doesn't touch existing nodes. To help you with starting a node configuration document from scratch (or in a scripted fashion), there is another command, act=mktemplate, which prints a blank but documented template which you can save and fill in. If you add placeholder=1 to the command line, then node_admin fills the template with easily matchable replacement placeholders, like so:
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