[wazari972]

I'm not sure to agree: if/as *nix systems do not use the extension to know the filetype, then `file`-like heuristics is the only other way to know the file nature, or do I miss someting?

[OskarS]

Presumably OpenOffice could pass along a thing that says "please print this PostScript file" so that the printer software knows which type of file it is printing and doesn't have to guess with "file". OpenOffice knows what type of file it's outputting, after all.

But your point arguably stands: if a user says "print file X", and you want different files printed using different logic (e.g. PDFs and PostScript files should be printed differently than text files), what other option is there other than using something like "file" to try and guess the file type? It would be very annoying for the user to have to specify each time from a massive list of possible optins.

[angrygoat]

I think the issue here is the question that should be being asked is: "is this a postscript file?". `file` answers a different question, "what is the most likely type for this file?"

[atanasi]

In the case of printing, the context provides some information. In particular, Erlang JAM file seems unlikely to be printed.

[pjc50]

Well, the true UNIX philosophy is that everything is a text file ...

.. but as one of the other comments says, programs which want specific interpretation should consider having their own heuristics, especially including "precedence". In the Excel example, it should be considering XLS and CSV first before trying other things.