magicmime is a Go package which allows you to discover a file's mimetype by looking for magic numbers in its content. It could be used as a supplementary for Go's mime package which only interprets the file extension to detect mimetypes. Internally, it implements libmagic(3) bindings.
Tested on Linux and Mac OS X, should be working on BSD. You could be able to build and make it working with Cygwin on Windows.
You might need to install devel packages for libmagic. On Debian, Ubuntu and CentOS, get libmagic-dev package from your package manager. On Mac OS X get libmagic via Homebrew: brew install libmagic. If you don't have the required dev packages, compilation will be terminated by an error saying magic.h cannot be found.
In order to start, go get this repository:
go get github.com/rakyll/magicmimeSee example_test.go
https://godoc.org/github.com/rakyll/magicmime
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