I just received a bunch of videos (for editing) and something weird happened. I was told the files are .mp4, but when I received them they did not have a filetype assigned to them.


I can add ".mp4" to the file name, which fixes the issue and allows my applications to recognize the files. Problem is, there are a lot of files.

Is there any way to easily add a ".mp4" to the end of all of the files at once? I'm willing to download an app for this if needed (Mac OS X 10.8.5)

Thank you!

  • 1
    Is there a reason why you're still on 10.8.5? Yosemite adds, among other things, a batch renaming ability.
    – user24601
    Commented Dec 2, 2014 at 0:03

2 Answers 2


If you're comfortable with the command line you can try this in the terminal.app:

for i in *; do mv "$i" "$i.mp4"; done;

Navigate to the directory with all of your files and run the above command.

  • 1
    Uhh… why are you piping text into sh? A simple command would really be sufficient.
    – 0942v8653
    Commented Dec 2, 2014 at 0:17
  • 1
    This seems to meet the OPs needs. Feel free to post a better solution to help the OP.
    – Stephen M.
    Commented Dec 2, 2014 at 0:25
  • 1
    If they are not comfortable with the terminal, they can navigate by opening the terminal, typing cd (with a space) and then dragging the folder that contains the files into the terminal window and hitting return. Then run the for command...
    – beroe
    Commented Dec 2, 2014 at 3:48
  • Worked great! Also, thank you @beroe, I always have to look up the commands for navigating since I rarely use Terminal
    – MrCarder
    Commented Dec 2, 2014 at 4:30

Sometimes the file extension is hidden, but it actually exists.

To show file extensions:

  1. Choose Finder > Preferences, then click Advanced.
  2. Select or deselect “Show all filename extensions.”


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