libextractor

GNU Libextractor is a library used to extract meta data from files. The goal is to provide developers of file-sharing networks, browsers or WWW-indexing bots with a universal library to obtain simple keywords and meta data to match against queries and to show to users instead of only relying on filenames. libextractor contains the shell command extract that, similar to the well-known file command, can extract meta data from a file an print the results to stdout.