Identify a file's format by scanning binary data for patterns (development files)
This is Release 5.x of Ian Darwin's (copyright but distributable) file(1) command, an implementation of the Unix File(1) command. It knows the 'magic number' of several thousands of file types. This version is the standard 'file' command for Linux, *BSD, and other systems. (See 'patchlevel.h' for the exact release number).