Well, it's been a total failure

Nick Sabalausky a at a.a
Wed Sep 15 22:16:20 PDT 2010


"Jonathan M Davis" <jmdavisProg at gmx.com> wrote in message 
news:mailman.227.1284590189.858.digitalmars-d at puremagic.com...
> On Wednesday, September 15, 2010 12:48:32 Nick Sabalausky wrote:
>> "Jonathan M Davis" <jmdavisProg at gmx.com> wrote in message
>> news:mailman.225.1284568096.858.digitalmars-d at puremagic.com...
>>
>> > If you're on a non-Windows system, the mime-type becomes far more
>> > important than
>> > the extension. Most programs in Linux (and I believe MacOS X as well)
>> > don't care
>> > about the extension. They just look at the mime type. Extensions become
>> > almost
>> > entirely a thing for the user. So, whether your file is useable becomes
>> > more of
>> > an issue of known mime type than known extension. Still, you don't
>> > generally
>> > want to just be making up extensions.
>>
>> I didn't think unix file systems had a concept of mime type.
>
> They don't have a concept of file extension either. Mime types has to do 
> with the
> contents of the file and file extensions has to do with the name of the 
> file. It's
> programs which interpret those, not the file system. Typically, on 
> Windows, the
> extension is used by the OS to determine which program to use to open a 
> file. In
> unix, it's the mime type that's used to determine that.
>
> The one bit of overlap there is the fact that Windows treats the exe 
> extension
> essentially the way that unix treats the executable file attribute.
>
> Now, I wouldn't advise ditching file extensions in unix, since it not only 
> can
> help the human using them but there are occasionally programs which check 
> the
> extension rather the mime type (so, ultimately, you may end up using both 
> the
> extension and the mime type), but it's primarily the mime type which is 
> used,
> and it's definitely the mime type which is used to determine which program 
> to use
> to open a file in the desktop environments.
>

Yea, but my question was more "how in the hell would it know the mime type 
of a file in the first place?" It's obviously not stored in the filename, 
and 99.9% is the time it's not stored in the file's data either.

Since then, someone mentioned it typically analyses the content of the file 
and infers the mime type based on that. That's news to me. It would seem 
limited and error-prone though, so I have a hard time believing it doesn't 
suppliment that content-analysis with extension-checking in many cases.




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