Extensions of the UNIX File Command and Magic File for File Type Identification

06-2-0050. The findings in this paper should not be construed as an official ARL or NARA position unless so indicated by other authorized documentation. File format identification is a core requirement for digital archives. The UNIX file command is among the most promising technologies for file type identification. This report describes extensions to the file command and magic file that enhance their utility for file format identification in archival systems. A File Format Library (database) has been created to manage information about file formats. This information includes file format name, MIME type, PRONOM Universal Identifier and file signature tests. There is a one-to-one correspondence between file formats and file signature tests. Precedence relations between file signature tests are explicitly expressed in the database. Published specifications for file formats are also collected in the library and are used to determine file signatures for the formats. When specifications have not been published for a file format, samples for files in those formats have been collected and analyzed to determine possible file signatures. File signature tests have been created for more than 800 file formats. Sample file