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FILE(1) 		 Copyrighted but distributable		       FILE(1)

       file - determine file type

       file  [	-bchikLnNprsvz	] [ -f namefile ] [ -F separator ] [ -m magic
       files ] file ...
       file -C [ -m magicfile ]

       This manual page documents version 4.17 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 number
       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 contains the result of compiling a program in a  form  understand
       able  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 adding local	definitions  to  /etc/magic,  preserve
       these  keywords.   People depend on knowing that all the readable files
       in a directory have the word text printed.  Dont  do  as  Berkeley
       did  and change shell commands text to shell script.  Note that
       the file /usr/share/file/magic is built mechanically from a large  num
       ber  of	small files in the subdirectory Magdir in the source distribu
       tion of this program.

       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
       its some sort of special file.  Any known file  types  appropriate  to
       the  system 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 .

       The magic number tests are used to check for files with data in partic
       ular fixed formats.  The canonical example of this  is  a  binary  exe
       cutable	(compiled  program)  a.out  file,  whose  format is defined in
       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 executable, and which of several types thereof.  The
       concept of magic number has been applied by extension to data  files.
       Any  file  with	some invariant identifier at a small fixed offset into
       the file can usually be described in this way.  The information identi
       fying  these  files is read from /etc/magic and the compiled magic file
       /usr/share/file/magic.mgc , or  /usr/share/file/magic  if  the  compile
       file  does  not exist. In addition file will look in $HOME/.magic.mgc ,
       or $HOME/.magic for magic entries.

       If a file does not match any of the entries in the magic  file,	it  is
       examined 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	Macin
       tosh  and  IBM  PC systems), UTF-8-encoded Unicode, UTF-16-encoded Uni
       code, 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 iden
       tified as text because 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 charac
       teristics 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 escape 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
       language 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)

       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 -m to debug a new
	       magic file before installing it.

       -C, --compile
	       Write a magic.mgc output file that contains a  pre-parsed  ver
	       sion of file.

       -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 stan
	       dard 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 order for this option to work, file changes the way it  han
	       dles  files  recognised	by the command itself (such as many of
	       the text file types, directories etc),  and  makes  use	of  an
	       alternative magic file.	(See FILES section, below).

       -k, --keep-going
	       Dont  stop  at the first match, keep going. Subsequent matches
	       will be prepended by \012- . (If you want  a  newline,  see
	       -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  containing  magic  numbers.
	       This  can be a single file, or a colon-separated list of files.
	       If a compiled magic file is found alongside, it	will  be  used
	       instead.   With	the  -i  or  --mime  option,  the program adds
	       ".mime" to each file name.

       -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
	       Dont 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(2) never read them.

       -r, --raw
	       Dont translate unprintable characters to \ooo.  Normally  file
	       translates  unprintable	characters  to their octal representa

       -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  option  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 partitions.

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

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

       --help  Print a help message and exit.

	      Default compiled list of magic numbers

	      Default list of magic numbers

	      Default  compiled  list  of  magic  numbers, used to output mime
	      types when the -i option is specified.

	      Default list of magic numbers, used to output  mime  types  when
	      the -i option is specified.

       The  environment  variable  MAGIC  can be used to set the default magic
       number file name.  If that variable is set, then file will not  attempt
       to  open $HOME/.magic.  file adds ".mime" and/or ".mgc" to the value of
       this variable as appropriate.  However, file has to exist in order  for
       file.mime  to  be considered.  The environment variable POSIXLY_CORRECT
       controls (on systems that support symbolic links), if file will attempt
       to follow symlinks or not. If set, then file follows symlink, otherwise
       it does not. This is also controlled by the L and h options.

       magic(5) - description of magic file format.
       strings(1), od(1), hexdump(1) - tools for examining non-textfiles.

       This program is believed to exceed the System V Interface Definition of
       FILE(CMD),  as  near  as one can determine from the vague language con
       tained therein.	Its behaviour is mostly compatible with the  System  V
       program	of  the same name.  This version knows more magic, however, so
       it will produce 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(1)
       command	derived  from  the System V one, but with some extensions.  My
       version differs from Suns only in minor ways.  It includes the  exten
       sion 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
       below) will collect additional or corrected magic file entries.	A con
       solidation 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

       $ 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, dynamically linked (uses shared libs),
       not stripped
       /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	number
       types.	This  slowed  the program down slightly but made it a lot more

       This program, based on the System V version, was written by Ian	Darwin
        without looking at anybody elses 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
       McMahon, cudcv@warwick.ac.uk, 1989.

       Guy Harris, guy@netapp.com, made many changes from 1993 to the present.

       Primary	development and maintenance from 1990 to the present by Chris
       tos Zoulas (christos@astron.com).

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

       Altered by Eric Fischer (enf@pobox.com), July, 2000, to identify  char
       acter codes and attempt to identify the languages of non-ASCII files.

       The  list  of  contributors  to	the "Magdir" directory (source for the
       /usr/share/file/magic file) is too long to include here.  You know  who
       you are; thank you.

       Copyright  (c)  Ian  F. Darwin, Toronto, Canada, 1986-1999.  Covered by
       the standard Berkeley Software Distribution  copyright;	see  the  file
       LEGAL.NOTICE in the source distribution.

       The files tar.h and is_tar.c were written by John Gilmore from his pub
       lic-domain tar 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?  Better yet, the magic
       file should be compiled into  binary  (say,  ndbm(3)  or,  better  yet,
       fixed-length  ASCII  strings  for  use in heterogenous network environ
       ments) for faster startup.  Then the program would run as fast  as  the
       Version	7 program of the same name, with the flexibility of the System
       V version.

       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
       simplistic, inefficient and requires recompilation to update.

       There should be an else clause to follow a series  of  continuation

       The  magic  file  and  keywords should have regular expression support.
       Their use of ASCII TAB as a field delimiter is ugly and makes  it  hard
       to edit the files, but is entrenched.

       It might be advisable to allow upper-case letters in keywords for e.g.,
       troff(1) commands vs man page macros.  Regular expression support would
       make this easy.

       The  program doesnt grok FORTRAN.  It should be able to figure FORTRAN
       by seeing some keywords which appear indented at  the  start  of  line.
       Regular expression support would make this easy.

       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.

       Another	optimisation  would  be  to sort the magic file so that we can
       just run down all the tests for the first byte, first word, first long,
       etc,  once  we  have fetched it.  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. From  as first 5  chars
       of  file)  because  they are not as good as other guesses (e.g. News
       groups: versus Return-Path:).  Still, if  the  others  dont  pan
       out, it should be possible to use the first guess.

       This  program is slower than some vendors file commands.  The new sup
       port for multiple character codes makes it even slower.

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

       file almost always returns 0. It returns a different if it cannot  open
       a file.

       You can obtain the original authors latest version by anonymous FTP on
       ftp.astron.com in the directory /pub/file/file-X.YZ.tar.gz

       This Debian version adds a number of  new  magix  entries.  It  can  be
       obtained from every site carrying a Debian distribution (ftp.debian.org
       and mirrors).

Debian/GNU Linux		  March 2006			       FILE(1)

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