Normally when a command acts on a folder, the entire contents of that folder are processed as well. For example, if you select a folder and click the Copy File button, that folder including all of its contents are copied.
File filters let you control which items within folders are processed. You might want to only copy the image files from sub-folders; or you might want to delete any .tmp files but leave all others unaffected. You can use a file filter to accomplish this.
There are a number of functions that support the use of file filters:
When using a filter in a function, there are two ways to define it:
Several of the internal commands let you specify a filter on the command line:
This is an example of a dialog that uses the filter control. This particular dialog is displayed when you run the Copy File function and the Copy Filter option is turned on. Opus displays the filter dialog at the beginning of the copy process, and you can define a new filter in place, or select a pre-configured one from the Filter drop-down.
The Clear button in the toolbar at the top of the filter control lets you quickly clear the existing filter. If you hold the Shift key down when you click it the filter will be reset to a simple template filter with some common conditions added.
Below the toolbar in the above screenshot is the area where the filter itself is defined, and below the filter control are some controls that are specific to the Copy or Delete filters:
Again, these options only apply to the copy and delete filters. When you use filters in other functions (for example, the Find or Synchronize tools), these options will not be displayed.
The dropdown menu to the right of the Filter: label lets you access functions to load, save and manage pre-configured filters. You can also do that via the Filters page in Preferences.
More:
Defining a Filter
Adding, Removing and Editing Clauses
Filter Clause Types