Extracts metadata about the current revision from your repository. This program is meant to be used by project build systems to extract properties that can be used in software version strings. Repository types supported include git, hg, bzr, and svn. It can create files containing variable and macro definitions suitable for C, C++, Java, sh, Python, Perl, PHP, lua, Javascript, and header files suitable for use with preprocessing Info.plist files. Emitted information includes the ID of the most recent commit, its branch, its date, and several other useful pieces of meta-information. There is support for reading and writing a cache file so autorevision will remain useful during a build from an unpacked distribution tarball.