A file extension is an optional alphanumeric identifier which comes after the last found period in a file name. A file extension itself does not define what type of data is in a file, but it does give a hint as to what is *supposed* to be in the file.

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74
votes
7answers
18k views

File extension for Markdown files?

Is there an official file extension for standalone Markdown files?
72
votes
4answers
27k views

Is there a tool that can determine the file type from containing data? [closed]

I sometimes get files from my clients that have the wrong file extension. For example, the name is image.jpg but the file is actually a TIFF image. In many cases I can clarify it by opening the file ...
40
votes
8answers
138k views

How do you remove a default program association for file types in Windows 7?

I somehow have set the default file type association for a file type in Windows 7. It doesn't appear to be possible to delete it from the "Change the file type associated with a file extension" ...
38
votes
13answers
12k views

Does it make sense converting a file to a higher audio bitrate?

When a certain file (mp4, flv, etc) has a 95 kbps audio bitrate - does it make sense outputing to a higher bitrate when converting to mp3 or other format (be it lossy or not)? Would this result in ...
30
votes
4answers
32k views

How do I find out the file type without an extension? [duplicate]

After recovering my HDD, I ended up with a lot of files with no extension. Many of them are .bin files. Is there any way to find out what file format they actually are? Many of them have no ...
13
votes
4answers
10k views

Find files filtered by multiple extensions

What is the correct syntax for: find . -type f -name \*.\(shtml\|css\) This works, but is inelegant: find . -type f -name \*.shtml > f.txt && find . -type f -name \*.css >> f.txt ...
10
votes
2answers
3k views

Show/hide extension of a file through OS X command line

I'm looking for a way, via terminal, to change whether or not a specific file's extension is shown in the Finder, something along the lines of: $ hideextension ~/music/somesong.mp3 Without having ...
9
votes
2answers
8k views

Programatically associate file extensions with application on Windows

I've just recently reinstalled Windows and in setting up my environment I've noticed that all my associations for the various programming languages I edit in Notepad++ have gone (naturally). I am ...
8
votes
3answers
2k views

On Windows, what filename extensions denote an executable?

On Windows, *.exe, *.bat, *.cmd, and *.com all represent programs or shell scripts that can be run, simply by double-clicking them. Are there any other filename extensions that indicate a file is ...
8
votes
4answers
981 views

Get Windows to treat files with the same extension differently

Multiple programs use the same file extension, but the formats are totally different and incompatible. For instance, I have .sch files on my computer that are in at least 5 different formats (TINA, ...
8
votes
2answers
5k views

There is a length limit to Windows file extensions?

If I want to create a new file extension for a binary/text data file that will open on my own application (extension ".mylongfileextensionname" for example), will Windows list it with my aplication ...
8
votes
3answers
6k views

What file format/database format does Picasa use?

I am trying to figure out what file format the .db file and .pmp files are. I tried using db_dump (Berkeley DB) for the .db files, but it seems that they are not Berkeley DB, or of an older version. I ...
7
votes
3answers
391 views

Why does Windows append .php to my php files but not other ones

I have many different types of files in a folder - .php, .css, .htm, .js, .docx, .xls, etc. The only file type that Windows (viewed from Windows Explorer) actually shows the extension are the .php ...
7
votes
3answers
3k views

How to extract a complete list of extension types within a directory?

Within a directory, and recursively within it's sub-directories, meaning every directory within a directory is processed, how do I compile a complete list of unique extensions within the directory? ...
7
votes
3answers
1k views

“file.myext” is not a valid Win32 application

I have written a registry that creates .myext. Double-clicking on my file.myext refers to my executable file (converted from a batch file that opens a .jar) which then opens my notepad application. ...
6
votes
3answers
1k views

What in the world is a .el8 file?

I am taking an online Latin class, and they gave me a video to watch. A .el8. What? el8? I have never heard of that in my life. It's supposed to be a video, so I tried renaming it to a .mov (Latin ...
6
votes
4answers
1k views

What does X denotes in ASPX, DOCX, XLSX, PPTX etc?

Previously there were ASP, DOC, XLS, PPT etc and now ASPX, DOCX, XLSX, PPTX respectively. What does X denotes in ASPX, DOCX, XLSX, PPTX etc?
6
votes
1answer
2k views

Is there a difference between .JPG and .jpg?

Files that have uppercase extensions (specifically .JPG) are not opening or being recognized in Windows Live Photo Gallery. .jpg files work as expected. What could be causing this issue?
6
votes
4answers
385 views

Are you allowed to come up with any desired file extension (for Unix, Linux, Windows)?

I want to create a file called "message" that contains text only. How does the system know what program to use to read it if I decide to call it: message.txt? message.dat? message.enc? message.cpz? ...
6
votes
6answers
35k views

How to open nokia photo images with .nrw extension?

I took some photos with my Nokia and they stayed with the .nrw extension. How can I open this format?
5
votes
2answers
667 views

How does a file have no extension?

Take for instance: cat /etc/passwd Why doesn't this file have an extension such as *.txt*, *.dat*, etc? Or does an extension exist, but it's just being hidden? Does this apply strictly to ...
5
votes
1answer
1k views

How to open file with default program from command line?

If I click on a file in a GUI file explorer, a default program is used to open it. This is useful for files which I don't know how to open from the command line. Is there a way to open a file with ...
5
votes
2answers
483 views

Windows file association for README, INSTALL, LICENSE and the like [duplicate]

Possible Duplicate: How to set the default program for opening files without an extension in Windows? Many files originating in the UNIX world come without file extension. Popular examples ...
5
votes
1answer
2k views

Running shortcut from command prompt without the .lnk extension (Windows)

I have created a folder (d:\shortcuts), created shortcuts for most applications in this folder and appended the folder path to the Path environment variable. Now all my applications are available from ...
5
votes
2answers
4k views

How to create a default association for files with no extension [duplicate]

Possible Duplicate: How to set the default program for opening files without an extension in Windows? I am using http://www.pnotepad.org/ (i wouldnt mind switching to something else if it ...
5
votes
2answers
1k views

Hiding files of a certain extension (.pyc) from Nautilus

I would like to hide every .pyc file from Nautilus. I use Ubuntu 10.04. What could I do?
5
votes
2answers
260 views

How can I associate multiple context menu types for one file extension in the registry?

I want to add custom context menu options for certain file extensions (like .zip-files) for a program I'm developing. However on many (but not all) PCs my software is going to be installed on 7-Zip is ...
4
votes
3answers
483 views

Applications are being opened by IE instead of running normally

I rewrote the Question to add everything that i tried so far. Many of my applications are being opened by Internet Explorer. (not all) For example when I run Firefox.exe (from shortcut) I get IE run ...
4
votes
2answers
1k views

Searching for Extensionless Files in Windows 7

I cannot for the life of me figure out a way to have Windows 7 Explorer search for files with no extension. In XP it was nice and simple: just search for files named *. but in 7, that does not work ...
4
votes
6answers
2k views

How can I find out about an unknown file extension?

When I have a random file of unknown format with a file extension I've never heard of, where can I turn to find out about the extension. The obvious choice is to google the extension along with some ...
4
votes
1answer
124 views

Windows explorer displays application path instead of file type

Windows explorer in Type columns sometime displays Type name like: "XXX File", sometime displays associated application name like "Adobe Acrobat Document", and for some application it displays full ...
4
votes
0answers
7k views

Always use the selected program, always greyed out [duplicate]

This one is driving me nuts, I'm trying to change the default program for sln files but for some reason the "always use the selected version" is always greyed out. How do I get that little grey box ...
3
votes
3answers
15k views

Differences between TIFF,TIF,tiff,tif

I have seen TIFF files having various extensions - TIFF,TIF,tiff,tif. Are they same? Can I safely rename a file with TIFF extension to tif or will it cause loss of information?
3
votes
3answers
3k views

How to change the extension of all selected files at once?

Its possible to rename files all at once. But its not possible to change the extension of selected files all at once. If windows doesn't support this facility .. then is there any batch script or ...
3
votes
1answer
385 views

How do I rename a file or folder to .something in Windows 7?

When I try to rename a folder to .svn or a file to .myemacs, for example, a popup says: You must specify a file name. Do you have a workaround ?
3
votes
2answers
418 views

How do I make a custom file extension open my java program?

what I'm asking is how to make any associated file type open my program with the corresponding data. For example, if you have a .doc file it opens Microsoft word with whatever is saved to that file. I ...
3
votes
1answer
1k views

Midnight Commander on OSX - bindings for file extensions and arrows

I am using Midnight Commander on Mac OS X (version 4.8.4) I have two problems and I would be very glad if you can help me: First: The binding for file extensions are set for Linux distribution. ...
3
votes
1answer
90 views

Handling files without an extension

I'd like to know how Windows XP, Vista and 7 handle files without a file extension. I'd test it myself, but I don't have access to a Windows machine currently. To my knowledge, Windows XP throws up ...
3
votes
1answer
1k views

Rename file in XP, only select file name, but show file extension

So if I have a file called: test.txt and I want to rename it, there are two options (depending on the Show already known file extension option): 1) ON: it selects everything (test.txt), meaning I ...
3
votes
2answers
2k views

Seach only no extention files on windows 7

How do i search files with no extension? For best effect i would like only <4kb and if i could search inside for the text thewordiwant I also have visual studios but i dont think writing ...
3
votes
2answers
4k views

Automatically hide files with certain extension in Windows

Is it possible for Windows to automatically hide files with a certain extension? Let's say some program generates a set of files (I cant alter the sources of the program), and I would like some of ...
3
votes
4answers
8k views

Input Error: There is no script engine for file extension “.vbs”

I keep getting it in command prompt, any idea why and how I may resolve the issue? Windows 7 Ultimate 32-Bit
3
votes
1answer
2k views

Creating custom file extension with windows registry

Ok, so I have been reading and googling this for a while now and I can't understand what is going wrong. I am trying to create a .int file extension in my registry so that I can add the ShellNew key ...
3
votes
1answer
2k views

How to set a default file extension for a specific download?

I'm using chrome web browser and when I download a file it saves the file with .jsp extension. Everytime I have to change the extension to my desired extension (i.e. .ica). Just setting the default ...
3
votes
1answer
255 views

Windows 2003 lost file extensions

I have a server with windows 2003, recently i installed a software in this server. When i restarted server my all files can't open sending to a command prompt saying: No program associated with ".exe" ...
3
votes
0answers
4k views

Search content of files with unknown extension

I have the problem that Windows Server 2008 does not seem to search through the content of files with a unknown extension (csv). How can I change this? I had already installed the indexing service ...
2
votes
2answers
256 views

Details about “Hide Extensions of Known file types” from Windows Explorer

What does "known file types" actually mean? What makes a file type "known"? Can I explicitly add or remove extensions/types from the list of "known" file types?
2
votes
3answers
2k views

changing the nature of .dat file

Some time ago I changed the way my computer reads .dat files by forcing it to always open with KM player. Now, if I save a .dat file in my laptop, its properties says that its a KMP-MPEG file. I want ...
2
votes
1answer
1k views

Is there a way to show only specific file extensions?

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 ...
2
votes
2answers
4k views

Google Chrome has taken over all HTML handling…

It's really getting on my nerves, but Google Chrome has taken over all HTML handling. For example, when you open Spotify... it runs C:/Users//AppData/Local/Spotify/flashdetect.html, but now that page ...