How does one reliably determine a file's type? File extension analysis is not acceptable. There must be a rubyesque tool similar to the UNIX file(1) command?
This is regarding MIME or content type, not file system classifications, such as directory, file, or socket.
If you're on a Unix machine try this:
mimetype = `file -Ib #{path}`.gsub(/\n/,"")
I'm not aware of any pure Ruby solutions that work as reliably as 'file'.
Edited to add: depending what OS you are running you may need to use 'i' instead of 'I' to get file to return a mime-type.
You could give shared-mime a try (gem install shared-mime-info). Requires the use ofthe Freedesktop shared-mime-info library, but does both filename/extension checks as well as "magic" checks... tried giving it a whirl myself just now but I don't have the freedesktop shared-mime-info database installed and have to do "real work," unfortunately, but it might be what you're looking for.
There is a ruby binding to libmagic that does what you need. This is available as a gem:
gem install ruby-filemagic
The documentation seems a little thin, but this should get you started:
$ irb
irb(main):001:0> require 'filemagic'
=> true
irb(main):002:0> fm = FileMagic.new
=> #<FileMagic:0x7fd4afb0>
irb(main):003:0> fm.file('foo.zip')
=> "Zip archive data, at least v2.0 to extract"
irb(main):004:0>
I couldn't get to install the ruby-filemagic
and
mimetype = file -Ib #{path}.gsub(/\n/,"")
gives the same result for .odt and .docx files
"application/x-zip" at least on ubuntu
I also tried the mimetype_fu gem which basically does a
file -mime -br "filename"
equivalent to the file -Ib from above
I recently found mimetype-fu. It seems to be the easiest reliable solution to get a file's mime type. The only caveat is that on a Windows machine it only uses the file extension; on Linux/OS X/Other Unix-y systems it works great.