Windows Wildcards – Using Wildcards with Files Having More Than 3 Characters Extensions

file extensionwildcardswindows

On Windows 7, I have a directory containing the following four files:

  • xxx.txt
  • xxx.txt2
  • xxx2.txt
  • xxx2.txt2

With the file have more than 3 character as a file extension, the behavior of the wildcard * seems odd:

dir *.txt

10/13/2014  04:14 PM                 6 xxx.txt
10/13/2014  04:17 PM                 6 xxx2.txt
10/13/2014  04:17 PM                 6 xxx2.txt2
10/13/2014  04:14 PM                 6 xxx.txt2
           4 File(s)             24 bytes
           0 Dir(s)   6,660,980,736 bytes free

I would expect to see only the two files with txt extension and not the ones with txt2 (like it would on a Linux machine). Does MS-DOS ignore the truncate the file extension to 3 characters or does it add automatically another wildcard at the end? If I want to delete only the files with txt extension and not the one with txt2, which command should I use?
Thanks

Best Answer

You're not using MS-DOS; it did not even allow file extensions longer than 3 characters. You're using the Windows command line – the cmd.exe shell, specifically.

But Windows indeed tries hard to remain compatible with programs from that era. So, up until Windows 8 (or something like that), all files with longer extensions have an alias that has the extension truncated, along with the name itself.

If you run dir /x, you'll likely see that each file has a "short name" assigned to it, which is limited to 8+3 characters, just like in MS-DOS and 16-bit Windows.

These names are there in case the user wanted to, let's say, upgrade to Windows 95 and still access their files through programs originally written for Windows 3.1 – so running a 16-bit program wouldn't crash, but would merely show C:\PROGRA~1 and C:\MYDOCU~1\CALENDAR.TXT in place of C:\Program Files and C:\My Documents\Calendar.txt.

(And yes, some people did actually use old 16-bit software even in Windows XP/Vista days... I'm pretty sure Windows 8 turn off the "short names" by default, however. This might be why @EBGreen isn't seeing the same 'problem'...)

Another thing to consider is that the old Windows shell, cmd.exe, has grown quite a few quirks and compatibility fixes in itself. For example, due to the way MS-DOS matched filenames, dir .txt meant the same as dir *.txt, even though it wasn't intentional. But people got used to the shorter syntax, and even though the Windows operating system itself doesn't treat .txt as a wildcard anymore, cmd.exe still accepts that syntax. (The dir command isn't a program on its own, but built into the shell.)

(Similarly, in the linked article, another wildcard quirk is described – Windows filenames can have no extension at all, but people are really used to typing *.*, therefore it means the same thing as * and the lone dot is ignored.)

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