I downloaded data in Ubuntu which has an extension .text/plain bit when I copied it to my Windows 10 through USB the file extension is changed to '.file'. What should I do now to open it?

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    Welcome to Ask Ubuntu. Ubuntu doesn't use extensions so it wouldn't be Ubuntu that is changing the name of the file. Whatever program you are using to copy/transfer the file to windows (most likely on the windows end) is changing the filename as a means of 'security' (as windows uses extension to control action; Ubuntu uses file contents). If you file filename (where filename is the name of your file) you can view the type of file according to Ubuntu or any *nix)
    – guiverc
    Commented Jan 18, 2019 at 6:40
  • @guiverc Ubuntu certainly does use file extensions to the same extent Windows does. File extensions are standardised by IANA along with media types and shells such as Gnome and KDE use them for identifying icons and appropriate actions, which is exactly what Windows Explorer does.
    – Ben
    Commented Jan 18, 2019 at 10:26
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    @Ben NO. Linux does not. Extensions are there to make it easier for humans to see what the file is. There is software for the desktop (!= Linux) that expect files to be named with an extension but Linux in itself does not care about that. And even then: the extensions are matched with a mime-type list.
    – Rinzwind
    Commented Jan 18, 2019 at 11:12
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    @Rinzwind Ubuntu = linux distribution(s), and Ubuntu certainly does use extensions. Linux kernel also uses extensions for some limited purposes, e.g. loader locating so files. Overall Linux distributions use extensions for the same purposes as Windows, and used by the equivalent components, Windows Explorer being the equivalent of the Linux graphical shells like Gnome and KDE. It's possible to install Windows without the graphical shell, in which case most uses of file extensions will not occur.
    – Ben
    Commented Jan 18, 2019 at 14:48
  • The desktop does but only to make things speed up a little bit. If those desktop coders would follow the correct method they too would scan for the 1st few bytes like linux does. And no: linux and ubuntu is not the same. Ubuntu is the desktop built on top of Linux.Those few tweaks made to the kernel don't matter
    – Rinzwind
    Commented Jan 18, 2019 at 15:25

2 Answers 2


It appears that Windows adds the .file extension to any file with an extension it doesn't know/recognise. Understandable, because text/plain is not a file extension but rather a 'content type'.

It seems that opening the file has worked on Ubuntu, because GNOME can "associate a media type with a file by examining both the filename suffix and the contents of the file" (Wikipedia).

To open the file in Windows, you can simply change the extension from .file to .txt, which is the most likely filetype. However, depending on where and for what purpose you downloaded the file, it could also be a .dat (data) or other file. If you don't know how to change the file type, I'd advice to Google for it as that seems out of scope for this Ubuntu-oriented site :)

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    Nice one. Just a pointer you can always expand/modify your answer (by clicking 'edit' below it) instead of deleting it and posting a new one :) Similarly you can 'undelete' an answer you deleted.
    – pomsky
    Commented Jan 18, 2019 at 8:00
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    More to the point, in Windows the character / in filename.text/plain is not a valid character for a filename. In Windows, filenames are not arbitrary sequences of bytes but a user-interface element with restrictions placed upon them to serve that purpose. Therefore control characters, and special shell metacharacters are not allowed. Whatever utility the poster used to copy the file has taken care of this issue.
    – Ben
    Commented Jan 18, 2019 at 10:22
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    @Ben This restriction (no / in filenames) also holds for Linux. AFAIR, there are only two forbidden characters in a Linux filename: / and \0. This means the file the OP downloaded CANNOT have an extension of .plain/text.
    – PerlDuck
    Commented Jan 18, 2019 at 12:20

Are you 100% sure that the file extension is .text/plain???? I'm 99% sure that it's not possible. Maybe you are talking about file content? Can you show us the output of runing file your_filewith_strange_extension? To open it on Windows, it should be enough renaming its extension to something you know. Do you know what type of file it is? if you downloaded a plain text file, you can rename it to your_filewith_strange_extension.txt. The output of running (on linux) file your_filewith_strange_extension should give you a hint about the file contents if you don't know what it is

  • The Readme.txt within the data says that it is .json file extention. im not able to open it, and when i opened it through .txt extension i cant able to load the data since it so 450Mb size.
    – ammu
    Commented Feb 4, 2019 at 7:25
  • @ammu if it's a json file, the content type is something like application/json, text/plain or something similar, but that's not the extension of the file. The extension could be .json, .txt, nothing at all, anything, etc. In unix, the extension is not important (well, originally, now sometimes it does). If you need to open it in Windows and you have to guess, I'll go with .jsonor .txt as my firsts guesses
    – Pablo K
    Commented Feb 5, 2019 at 13:07
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    @ammu if in linux you run head the_450mb_file.json, what shows you? it seems like the starting of a json file? and if you run tail the_450mb_file.json??? The idea is that you can see if it's a real json or not. The only way I could open big files on windows was with notepad++, but the last time I did it was like 10 years ago
    – Pablo K
    Commented Feb 5, 2019 at 13:20
  • actually the content is latex file of a paper, but the extension is given as file. i cant able to load the data as .txt
    – ammu
    Commented Feb 14, 2019 at 17:45
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    So, to summarize: the file extension couldn't be text/plain, because file names can't have / on it. Also, latex content-type is application/x-latex, not text/plain. Maybe you have a latex file that when you open it, it shows json data? something similar to having a .docx file that when you open it with microsoft word, inside you see a json? ({key1: val1, key2: val2, (...)}). If that's the case, you can open it with a latex editor, (latexbase.com is an online editor), if it's ok, you can rename your file to something.tex
    – Pablo K
    Commented Feb 15, 2019 at 3:20

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