To expand a little on what blueroly said, there are multiple ways to perform searches in Opus. For a quick search to find specific files or file types, I prefer to use the Find as you Type filter along with Flat view.
However for what you're asking, I'd use the Utility Panel Find filter as blueroly mentioned. Below is a screen grab showing how I set it up to search for my last name (Zeman) in all files ending in .CSV, .TXT, or .LOG
Change your "Type" from text document to [Files Only] and it should work.
CSV files are text files, so I can understand why it confused you. And I really don't have an answer as to why the text files type doesn't work unless Opus is actually searching for standard text files (thereby ignoring CSV files), but that's only a guess on my part.
That Type drop-down lists the Windows file types. "Text Document" is a type defined by Windows (unless it has been overwritten by a 3rd party text editor) which typically only matches *.txt.
That's just how file-types work on Windows. If you view a directory with .csv files in them in Opus or Explorer then you'll see the Type column does not say "Text Document" for them. (Unless something has assigned the .csv extension to that type, which would be unusual.)
If you want to match by extension, rather than file-type, then use a wildcard as John suggests.
Alas, nothing subtle about me. I genuinely missed it. Thank you for pointing it out.
Excuses and hand-waving on demand. There is a lot to absorb (and at the same time getting used to win7).
All them years of XP are dying hard this month.
Windows makes too much fuss over file extensions. I'd like a giant switch that says they are just part of the file name !
Suppose I wanted to search within a few file type?, but not all (eg *.php, *.html, *.phtml, *.xml) I guess I will find that under the advanced tab.
I've not yet found a good workflow or output configuration for text search. Here is my ideal scenario:
Specify a set of files, could be a number of types
Specify a string (regexp or not)
Search results are shown and can be clicked/manipulated as the search continues (search can be cancelled, ie no long pause of fruitlessly continuing thru thousands of file).
Results panes show the file name, the line where found (with sought expression highlighted)
Clicking on a result line show the file n the viewer pane (or can be configured to open in some editor/viewr).
I may be asking too much, maybe I have to use wingrep or an IDE for that kind of functionality... ?