Missing Extensions
March 16, 2004 1:31 PM   Subscribe

How do you find out the extension of a file where it has been removed? I think it's a compressed file but I can't seem to get the slightest clue beyond that.
posted by Zootoon to Computers & Internet (7 answers total)
Sometimes you can open such a file in a text editor and see clues at the very top. In Windows, just right-click on it, and try to open it in WordPad, or temporarily rename it with a .txt suffix and double-click on it. On the Mac, you can just drag-and-drop it on BBedit or Microsoft Word, or, go to the File menu in Word, choose Open, then change to File Type to All, navigate to find the file, then open it.

Alternately, if the file is a system or program file that does not have a common name, do as search on the Internet for it and see if it exists elsewhere--with the suffix.

Alternately, drag-and-drop it on WinZip or Stuffit Expander, or right-click in Windows. Either program should be able to recognize its file type without the extension.
posted by Mo Nickels at 1:58 PM on March 16, 2004

If you're using linux or any of the common BSDs, or presumably OSX, use the file command:
sean@tau:~$ file mystery_file
mystery_file: Zip archive data, at least v2.0 to extract
sean@tau:~$ file other_mystery_file
other_mystery_file: Ogg data, Vorbis audio, mono, 32000 Hz, ~72000 bps, created by: Xiph.Org libVorbis I (post-1.0 CVS)

posted by duckstab at 2:49 PM on March 16, 2004

file is one of many shell tools that comes with cygwin, a port of many GNU and POSIX utilities to Windows. (Cygwin has been mentioned in passing on ask.mefi before.) Once you've installed cygwin, fire up a bash shell and run the commands duckstab describes above. (If cygwin gets added to your Windows command path, you ought even to be able to run file from your Windows COMMAND.EXE or CMD.EXE (depending on Windows version).)
posted by dsandl at 4:04 PM on March 16, 2004

Or just post (the first part of) the file somewhere online or as a hex dump here, I'm sure we should be able to decode most files.

Also, how did you manage to remove the file extension? All we ask as compensation is a little schandenfreude.
posted by fvw at 4:10 PM on March 16, 2004

Wotsit, the programmer's file format resource. (There are others).
posted by dhartung at 9:51 PM on March 16, 2004

Response by poster: how did you manage to remove the file extension?
I didn't, the truth is I downloaded it from emule and it didn't have an extension. or comments. The truth is it's not all that important and I could get it elsewhere but it's gotten to me that I had no easy way of finding out what type of file it was. Isn't there any mini-app that looks at a file with no extension and says "Mmm, looks like a ..." ?
posted by Zootoon at 10:13 PM on March 16, 2004

So, pornography then? :-). Filesize should tell you a lot, if it's 32k-512k, it's quite likely a picture or a text document. Larger, it's quite probably a video or an archive.

I don't know of any programs for windows that detect file format, however a lot of applications autodetect filetype if it's one they support. Try opening it with photoshop, word, winzip etc and see if they can open it.
posted by fvw at 6:52 PM on March 17, 2004

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