Unix file extensions (Was: make apache2 serve file as htmL...)

[Christopher Browne]

On 1/14/07, Howard Gibson <hgibson-MwcKTmeKVNQ at public.gmane.org> wrote:
> On Fri, 12 Jan 2007 21:46:10 +0000
> "Christopher Browne" <cbbrowne-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> >
> > If you examine filesystem code, you'll find that there Is No Such
> > Thing As A File Extension.  They don't exist.  They aren't supported.
> > (Well, they are in msdosfs and ISO9660, which, respectively, emulate
> > FSes from Microsoft and DEC.  But not in the *usual* Unixy
> > filesystems...)
> >
> > Unix programming tools don't use them, either.
> >
> > Unix programming tools often use file suffixes to infer information
> > about file type, but a suffix is not the same thing as an "extension."
>
> Christopher,
>
>    It looks like I am going to have to transition from FVWM and the file mananger XFM to the Gnome distributed with Fedora Core_5.  It is too bad, since XFM can use magic files to identify stuff.  You do not need file extensions.
>
>    Progress -- two steps forward, one step back.  I hope.

Unfortunately, Nautilus wound up designed (not surprisingly, when
written by Mac folk who expected a "magic number" on their former
platform) to depend on suffix information to identify stuff.

I was unhappy with this, and expressed opinion, at the time.

As you have observed, /etc/magic can be used to provide signatures to
identify stuff, generally with a LOT more accuracy than file
extensions ever offered.

Unfortunately, that accuracy comes at a cost:  You have to read
roughly the first 500 bytes of each file in order to match it against
/etc/magic.  Which, for a directory with a large number of entries,
means a lot of I/O.  That was why the Nautilus maintainers declined to
use /etc/magic by default :-(.
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