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FILE(1)			  BSD General Commands Manual		       FILE(1)

     file -- determine file type

     file [-bchikLnNprsvz] [--mime-type] [--mime-encoding] [-f namefile]
	  [-F separator] [-m magicfiles] file
     file -C [-m magicfile]
     file [--help]

     This manual page documents	version	"5.03" of the file command.

     file tests	each argument in an attempt to classify	it.  There are three
     sets of tests, performed in this order: filesystem	tests, magic tests,
     and language tests.  The first test that succeeds causes the file type to
     be	printed.

     The type printed will usually contain one of the words text (the file
     contains only printing characters and a few common	control	characters and
     is	probably safe to read on an ASCII terminal), executable	(the file con-
     tains the result of compiling a program in	a form understandable to some
     UNIX kernel or another), or data meaning anything else (data is usually
     `binary' or non-printable).  Exceptions are well-known file formats (core
     files, tar	archives) that are known to contain binary data.  When modify-
     ing magic files or	the program itself, make sure to preserve these
     keywords.	Users depend on	knowing	that all the readable files in a di-
     rectory have the word `text' printed.  Don't do as	Berkeley did and
     change `shell commands text' to `shell script'.

     The filesystem tests are based on examining the return from a stat(2)
     system call.  The program checks to see if	the file is empty, or if it's
     some sort of special file.	 Any known file	types appropriate to the sys-
     tem you are running on (sockets, symbolic links, or named pipes (FIFOs)
     on	those systems that implement them) are intuited	if they	are defined in
     the system	header file <sys/stat.h>.

     The magic tests are used to check for files with data in particular fixed
     formats.  The canonical example of	this is	a binary executable (compiled
     program) a.out file, whose	format is defined in <elf.h>, <a.out.h>	and
     possibly <exec.h> in the standard include directory.  These files have a
     `magic number' stored in a	particular place near the beginning of the
     file that tells the UNIX operating	system that the	file is	a binary exe-
     cutable, and which	of several types thereof.  The concept of a `magic'
     has been applied by extension to data files.  Any file with some invari-
     ant identifier at a small fixed offset into the file can usually be de-
     scribed in	this way.  The information identifying these files is read
     from the compiled magic file /usr/share/misc/magic.mgc, or	the files in
     the directory /usr/share/misc/magic if the	compiled file does not exist.
     In	addition, if $HOME/.magic.mgc or $HOME/.magic exists, it will be used
     in	preference to the system magic files.

     If	a file does not	match any of the entries in the	magic file, it is ex-
     amined to see if it seems to be a text file.  ASCII, ISO-8859-x, non-ISO
     8-bit extended-ASCII character sets (such as those	used on	Macintosh and
     IBM PC systems), UTF-8-encoded Unicode, UTF-16-encoded Unicode, and
     EBCDIC character sets can be distinguished	by the different ranges	and
     sequences of bytes	that constitute	printable text in each set.  If	a file
     passes any	of these tests,	its character set is reported.	ASCII,
     ISO-8859-x, UTF-8,	and extended-ASCII files are identified	as `text' be-
     cause they	will be	mostly readable	on nearly any terminal;	UTF-16 and
     EBCDIC are	only `character	data' because, while they contain text,	it is
     text that will require translation	before it can be read.	In addition,
     file will attempt to determine other characteristics of text-type files.
     If	the lines of a file are	terminated by CR, CRLF,	or NEL,	instead	of the
     Unix-standard LF, this will be reported.  Files that contain embedded es-
     cape sequences or overstriking will also be identified.

     Once file has determined the character set	used in	a text-type file, it
     will attempt to determine in what language	the file is written.  The lan-
     guage tests look for particular strings (cf.  <names.h> ) that can	appear
     anywhere in the first few blocks of a file.  For example, the keyword .br
     indicates that the	file is	most likely a troff(1) input file, just	as the
     keyword struct indicates a	C program.  These tests	are less reliable than
     the previous two groups, so they are performed last.  The language	test
     routines also test	for some miscellany (such as tar(1) archives).

     Any file that cannot be identified	as having been written in any of the
     character sets listed above is simply said	to be `data'.

     -b, --brief
	     Do	not prepend filenames to output	lines (brief mode).

     -c, --checking-printout
	     Cause a checking printout of the parsed form of the magic file.
	     This is usually used in conjunction with the -m flag to debug a
	     new magic file before installing it.

     -C, --compile
	     Write a magic.mgc output file that	contains a pre-parsed version
	     of	the magic file or directory.

     -e, --exclude testname
	     Exclude the test named in testname	from the list of tests made to
	     determine the file	type. Valid test names are:

	       EMX application type (only on EMX).

	       Various types of	text files (this test will try to guess	the
	       text encoding, irrespective of the setting of the `encoding'

	       Different text encodings	for soft magic tests.

	       Looks for known tokens inside text files.

	       Prints details of Compound Document Files.

	       Checks for, and looks inside, compressed	files.

	       Prints ELF file details.

	       Consults	magic files.

	       Examines	tar files.

     -f, --files-from namefile
	     Read the names of the files to be examined	from namefile (one per
	     line) before the argument list.  Either namefile or at least one
	     filename argument must be present;	to test	the standard input,
	     use `-' as	a filename argument.

     -F, --separator separator
	     Use the specified string as the separator between the filename
	     and the file result returned. Defaults to `:'.

     -h, --no-dereference
	     option causes symlinks not	to be followed (on systems that	sup-
	     port symbolic links). This	is the default if the environment
	     variable POSIXLY_CORRECT is not defined.

     -i, --mime
	     Causes the	file command to	output mime type strings rather	than
	     the more traditional human	readable ones. Thus it may say
	     `text/plain; charset=us-ascii' rather than	`ASCII text'.  In or-
	     der for this option to work, file changes the way it handles
	     files recognized by the command itself (such as many of the text
	     file types, directories etc), and makes use of an alternative
	     `magic' file.  (See the FILES section, below).

     --mime-type, --mime-encoding
	     Like -i, but print	only the specified element(s).

     -k, --keep-going
	     Don't stop	at the first match, keep going.	Subsequent matches
	     will be have the string `\012- ' prepended.  (If you want a new-
	     line, see the `-r'	option.)

     -L, --dereference
	     option causes symlinks to be followed, as the like-named option
	     in	ls(1) (on systems that support symbolic	links).	 This is the
	     default if	the environment	variable POSIXLY_CORRECT is defined.

     -m, --magic-file list
	     Specify an	alternate list of files	and directories	containing
	     magic.  This can be a single item,	or a colon-separated list.  If
	     a compiled	magic file is found alongside a	file or	directory, it
	     will be used instead.

     -n, --no-buffer
	     Force stdout to be	flushed	after checking each file.  This	is
	     only useful if checking a list of files.  It is intended to be
	     used by programs that want	filetype output	from a pipe.

     -N, --no-pad
	     Don't pad filenames so that they align in the output.

     -p, --preserve-date
	     On	systems	that support utime(2) or utimes(2), attempt to pre-
	     serve the access time of files analyzed, to pretend that file
	     never read	them.

     -r, --raw
	     Don't translate unprintable characters to \ooo.  Normally file
	     translates	unprintable characters to their	octal representation.

     -s, --special-files
	     Normally, file only attempts to read and determine	the type of
	     argument files which stat(2) reports are ordinary files.  This
	     prevents problems,	because	reading	special	files may have pecu-
	     liar consequences.	 Specifying the	-s option causes file to also
	     read argument files which are block or character special files.
	     This is useful for	determining the	filesystem types of the	data
	     in	raw disk partitions, which are block special files.  This op-
	     tion also causes file to disregard	the file size as reported by
	     stat(2) since on some systems it reports a	zero size for raw disk

     -v, --version
	     Print the version of the program and exit.

     -z, --uncompress
	     Try to look inside	compressed files.

     -0, --print0
	     Output a null character `\0' after	the end	of the filename. Nice
	     to	cut(1) the output. This	does not affect	the separator which is
	     still printed.

     --help  Print a help message and exit.

     /usr/share/misc/magic.mgc	Default	compiled list of magic.
     /usr/share/misc/magic	Directory containing default magic files.

     The environment variable MAGIC can	be used	to set the default magic file
     name.  If that variable is	set, then file will not	attempt	to open
     $HOME/.magic.  file adds `.mgc' to	the value of this variable as appro-
     priate.  The environment variable POSIXLY_CORRECT controls	(on systems
     that support symbolic links), whether file	will attempt to	follow sym-
     links or not. If set, then	file follows symlink, otherwise	it does	not.
     This is also controlled by	the -L and -h options.

     magic(5), strings(1), od(1), hexdump(1,) file(1posix)

     This program is believed to exceed	the System V Interface Definition of
     FILE(CMD),	as near	as one can determine from the vague language contained
     therein.  Its behavior is mostly compatible with the System V program of
     the same name.  This version knows	more magic, however, so	it will	pro-
     duce different (albeit more accurate) output in many cases.

     The one significant difference between this version and System V is that
     this version treats any white space as a delimiter, so that spaces	in
     pattern strings must be escaped.  For example,

	   >10	   string  language impress	   (imPRESS data)

     in	an existing magic file would have to be	changed	to

	   >10	   string  language\ impress	   (imPRESS data)

     In	addition, in this version, if a	pattern	string contains	a backslash,
     it	must be	escaped.  For example

	   0	   string	   \begindata	   Andrew Toolkit document

     in	an existing magic file would have to be	changed	to

	   0	   string	   \\begindata	   Andrew Toolkit document

     SunOS releases 3.2	and later from Sun Microsystems	include	a file command
     derived from the System V one, but	with some extensions.  My version dif-
     fers from Sun's only in minor ways.  It includes the extension of the `&'
     operator, used as,	for example,

	   >16	   long&0x7fffffff >0		   not stripped

     The magic file entries have been collected	from various sources, mainly
     USENET, and contributed by	various	authors.  Christos Zoulas (address be-
     low) will collect additional or corrected magic file entries.  A consoli-
     dation of magic file entries will be distributed periodically.

     The order of entries in the magic file is significant.  Depending on what
     system you	are using, the order that they are put together	may be incor-
     rect.  If your old	file command uses a magic file,	keep the old magic
     file around for comparison	purposes (rename it to
     /usr/share/misc/magic.orig	).

	   $ file file.c file /dev/{wd0a,hda}
	   file.c:   C program text
	   file:     ELF 32-bit	LSB executable,	Intel 80386, version 1 (SYSV),
		     dynamically linked	(uses shared libs), stripped
	   /dev/wd0a: block special (0/0)
	   /dev/hda: block special (3/0)

	   $ file -s /dev/wd0{b,d}
	   /dev/wd0b: data
	   /dev/wd0d: x86 boot sector

	   $ file -s /dev/hda{,1,2,3,4,5,6,7,8,9,10}
	   /dev/hda:   x86 boot	sector
	   /dev/hda1:  Linux/i386 ext2 filesystem
	   /dev/hda2:  x86 boot	sector
	   /dev/hda3:  x86 boot	sector,	extended partition table
	   /dev/hda4:  Linux/i386 ext2 filesystem
	   /dev/hda5:  Linux/i386 swap file
	   /dev/hda6:  Linux/i386 swap file
	   /dev/hda7:  Linux/i386 swap file
	   /dev/hda8:  Linux/i386 swap file
	   /dev/hda9:  empty
	   /dev/hda10: empty

	   $ file -i file.c file /dev/{wd0a,hda}
	   file.c:	text/x-c
	   file:	application/x-executable
	   /dev/hda:	application/x-not-regular-file
	   /dev/wd0a:	application/x-not-regular-file

     There has been a file command in every UNIX since at least	Research
     Version 4 (man page dated November, 1973).	 The System V version intro-
     duced one significant major change: the external list of magic types.
     This slowed the program down slightly but made it a lot more flexible.

     This program, based on the	System V version, was written by Ian Darwin
     <> without looking at anybody else's source code.

     John Gilmore revised the code extensively,	making it better than the
     first version.  Geoff Collyer found several inadequacies and provided
     some magic	file entries.  Contributions by	the `&'	operator by Rob	McMa-
     hon,, 1989.

     Guy Harris,, made many changes from	1993 to	the present.

     Primary development and maintenance from 1990 to the present by Christos
     Zoulas (

     Altered by	Chris Lowth,, 2000: Handle the -i option to
     output mime type strings, using an	alternative magic file and internal

     Altered by	Eric Fischer (, July, 2000, to identify charac-
     ter codes and attempt to identify the languages of	non-ASCII files.

     Altered by	Reuben Thomas (, 2007 to 2008, to improve MIME
     support and merge MIME and	non-MIME magic,	support	directories as well as
     files of magic, apply many	bug fixes and improve the build	system.

     The list of contributors to the `magic' directory (magic files) is	too
     long to include here.  You	know who you are; thank	you.  Many contribu-
     tors are listed in	the source files.

     Copyright (c) Ian F. Darwin, Toronto, Canada, 1986-1999.  Covered by the
     standard Berkeley Software	Distribution copyright;	see the	file LEGAL.NO-
     TICE in the source	distribution.

     The files tar.h and is_tar.c were written by John Gilmore from his	pub-
     lic-domain	tar(1) program,	and are	not covered by the above license.

     There must	be a better way	to automate the	construction of	the Magic file
     from all the glop in Magdir.  What	is it?

     file uses several algorithms that favor speed over	accuracy, thus it can
     be	misled about the contents of text files.

     The support for text files	(primarily for programming languages) is sim-
     plistic, inefficient and requires recompilation to	update.

     The list of keywords in ascmagic probably belongs in the Magic file.
     This could	be done	by using some keyword like `*' for the offset value.

     Complain about conflicts in the magic file	entries.  Make a rule that the
     magic entries sort	based on file offset rather than position within the
     magic file?

     The program should	provide	a way to give an estimate of `how good'	a
     guess is.	We end up removing guesses (e.g.  `Fromas first	5 chars	of
     file) because' they are not as good as other guesses (e.g.	 `Newsgroups:'
     versus `Return-Path:' ).  Still, if the others don't pan out, it should
     be	possible to use	the first guess.

     This manual page, and particularly	this section, is too long.

     file returns 0 on success,	and non-zero on	error.

     You can obtain the	original author's latest version by anonymous FTP on in the directory /pub/file/file-X.YZ.tar.gz

BSD				October	9, 2008				   BSD


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