CODE EXAMPLE FOR RUBY

ruby get file extension

path = "/path/to/xyz.mp4"

File.basename(path)         # => "xyz.mp4"
File.extname(path)          # => ".mp4"
File.basename(path, ".mp4") # => "xyz" OR
File.basename(path, ".*")   # => "xyz"
File.dirname(path)          # => "/path/to"

# Alternative to File.extname(path) for multiple extension periods
def full_extname(path)
  ext = File.basename(path).split('.', 2)[1]
  ext.nil? ? '' : ".#{ext}"
end

full_extname('/path/to/xyz.mp4')				# => ".mp4"
full_extname('/path/to/xyz.my.custom.ext.mp4')	# => ".my.custom.ext.mp4"
full_extname('/path/to/xyz')					# => ""