Call me crazy, but I'm sure I remember this capability existing in previous versions of Windows. In Windows 7, we can have file extensions Off... or On. Pick one. Is there some obscure switch buried in the registry to have Explorer show specific extensions, but leave the rest hidden?

In my case, I'd like to always show extensions for text files (*.txt, *.csv, *.tdt), because I frequently have to handle flat files which may come in with a .txt extension where I need it to be .csv, for example. I'd rather not have extensions on all the time, it's just clutter for almost all files.

  • I recall the setting I toggle on all fresh Windows installs, is titled "Show known file type extensions" - so perhaps you can accomplish your means through editing the extension/application association list thingy. Though that sounds like a horrible solution - hence the comment rather than an answer. Sep 28 '11 at 23:22
  • I believe that if you disassociate the extension with a program then it will show the file extension for only that file.
    – kobaltz
    Sep 28 '11 at 23:34
  • obscure switch in registry "NeverShowExt" , works opposite of your desired intent. making the files of that extention type "superHidden" No more info provided here, use web search. it will NOT do what you want, it is just one of the registry items.
    – Psycogeek
    Sep 29 '11 at 5:17
  • @Psycogeek: AlwaysShowExt must be even more obscure, then? (It exists.)
    – user1686
    Sep 29 '11 at 11:53
  • You have to have MI5 clearance to use it though :-)
    – Psycogeek
    Sep 29 '11 at 13:03

Open the Registry Editor, navigate to HKCR (although HKCU\Software\Classes would be a better location, but most are lazy). For every file type, create a zero-length string value named AlwaysShowExt.

For example, if you have .txt:

  1. Navigate to the subkey for the extension – HKCR\.txt – and note the data stored in the "(Default)" value – it usually says txtfile.

  2. Navigate to the file type subkey HKCR\txtfile, right-click the value list, choose New → String value, and name the new value AlwaysShowExt.

Not all extensions have separate subkeys for file types – sometimes all information is kept directly under HKCR\.myext. In such cases, AlwaysShowExt goes directly to the extension subkey as well.

It is very likely that there are dedicated programs for editing file types, possibly with support for AlwaysShowExt and other flags. I don't know any to recommend, though.

  • Groovy, that did it! Well, almost. Adding that tag to HKCR\txtfile and HKCR\tdt_auto_file worked for .txt, .log, and .tdt extensions, but adding it to HKCR\Excel.CSV, HKCR\.csv, and HKCR\.csv\Excel.CSV has not changed the behavior for .csv files. Is there an extra step here?
    – user49214
    Sep 29 '11 at 15:13
  • FYI - Restart Explorer.exe for changes to take effect.
    – Keith
    Apr 15 '14 at 2:25

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