file Determine file type. Give a description of the type of the specified file. Works fine for files with no file extension: file {{filename}} Look inside a zipped file and determine the file type(s) inside: file -z {{foo.zip}} Allow file to work with special or device files: file -s {{filename}} Don't stop at first file type match; keep going until the end of the file: file -k {{filename}} Determine the mime encoding type of a file: file -I {{filename}}