@(#) $File: README,v 1.46 2013/03/25 14:33:10 christos Exp $
Phone: Do not even think of telephoning me about this program. Send cash first!
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).
You can download the latest version of the original sources for file from:
A public read-only git repository of the same sources is available at:
The major changes for 5.x are CDF file parsing, indirect magic, and overhaul in mime and ascii encoding handling.
The major feature of 4.x is the refactoring of the code into a library, and the re-write of the file command in terms of that library. The library itself, libmagic can be used by 3rd party programs that wish to identify file types without having to fork() and exec() file. The prime contributor for 4.0 was Mans Rullgard.
UNIX is a trademark of UNIX System Laboratories.
The prime contributor to Release 3.8 was Guy Harris, who put in megachanges including byte-order independence.
The prime contributor to Release 3.0 was Christos Zoulas, who put in hundreds of lines of source code changes, including his own ANSIfication of the code (I liked my own ANSIfication better, but his (__P()) is the "Berkeley standard" way of doing it, and I wanted UCB to include the code...), his HP-like "indirection" (a feature of the HP file command, I think), and his mods that finally got the uncompress (-z) mode finished and working.
This release has compiled in numerous environments; see PORTING for a list and problems.
This fine freeware file(1) follows the USG (System V) model of the file command, rather than the Research (V7) version or the V7-derived 4. Berkeley one. That is, the file /etc/magic contains much of the ritual information that is the source of this program's power. My version knows a little more magic (including tar archives) than System V; the /etc/magic parsing seems to be compatible with the (poorly documented) System V /etc/magic format (with one exception; see the man page).
In addition, the /etc/magic file is built from a subdirectory for easier(?) maintenance. I will act as a clearinghouse for magic numbers assigned to all sorts of data files that are in reasonable circulation. Send your magic numbers, in magic(5) format please, to the maintainer, Christos Zoulas.
COPYING - read this first.
README - read this second (you are currently reading this file).
INSTALL - read on how to install
src/apprentice.c - parses /etc/magic to learn magic
src/apptype.c - used for OS/2 specific application type magic
src/asprintf.c - replacement for OS's that don't have it.
src/ascmagic.c - third & last set of tests, based on hardwired assumptions.
src/asctime_r.c - for systems that don't have it.
src/asprintf.c - for systems that don't have it.
src/cdf.c - parser for Microsoft Compound Document Files
src/cdf_time.c - time converter for CDF.
src/compress.c - handles decompressing files to look inside.
src/ctime_r.c - for systems that don't have it.
src/encoding.c - handles unicode encodings
src/file.c - the main program
src/file.h - header file
src/fsmagic.c - first set of tests the program runs, based on filesystem info
src/funcs.c - utilility functions
src/getopt_long.c - for systems that don't have it.
src/getline.c - for systems that don't have it.
src/is_tar.c, tar.h - knows about tarchives (courtesy John Gilmore).
src/names.h - header file for ascmagic.c
src/magic.c - the libmagic api
src/print.c - print results, errors, warnings.
src/readcdf.c - CDF wrapper.
src/readelf.[ch] - Stand-alone elf parsing code.
src/softmagic.c - 2nd set of tests, based on /etc/magic
src/strlcat.c - for systems that don't have it.
src/strlcpy.c - for systems that don't have it.
src/vasprintf.c - for systems that don't have it.
doc/file.man - man page for the command
doc/magic.man - man page for the magic file, courtesy Guy Harris. Install as magic.4 on USG and magic.5 on V7 or Berkeley; cf Makefile.
If you submit a new magic entry please make sure you read the following guidelines:
- Initial match is preferably at least 32 bits long, and is a unique match
- If this is not feasible, use additional check
- Match of <= 16 bits are not accepted
- Delay printing string as much as possible, don't print output too early
Avoid printf arbitrary byte as string, which can be a source of crash and buffer overflow
Provide complete information with entry:
- One line short summary
- Optional long description
- File extension, if applicable
- Full name and contact method (for discussion when entry has problem)
- Further reference, such as documentation of format
Parts of this software were developed at SoftQuad Inc., developers of SGML/HTML/XML publishing software, in Toronto, Canada. SoftQuad was swallowed up by Corel in 2002 and does not exist any longer.