1 .\" $File: file.man,v 1.117 2015/06/03 19:51:27 christos Exp $
7 .Nd determine file type
11 .Op Fl bcEhiklLNnprsvzZ0
14 .Op Fl Fl mime-encoding
19 .Op Fl m Ar magicfiles
20 .Op Fl P Ar name=value
25 .Op Fl m Ar magicfiles
29 This manual page documents version __VERSION__ of the
34 tests each argument in an attempt to classify it.
35 There are three sets of tests, performed in this order:
36 filesystem tests, magic tests, and language tests.
39 test that succeeds causes the file type to be printed.
41 The type printed will usually contain one of the words
43 (the file contains only
44 printing characters and a few common control
45 characters and is probably safe to read on an
49 (the file contains the result of compiling a program
50 in a form understandable to some
55 meaning anything else (data is usually
58 Exceptions are well-known file formats (core files, tar archives)
59 that are known to contain binary data.
60 When modifying magic files or the program itself, make sure to
61 .Em "preserve these keywords" .
62 Users depend on knowing that all the readable files in a directory
66 Don't do as Berkeley did and change
67 .Dq shell commands text
71 The filesystem tests are based on examining the return from a
74 The program checks to see if the file is empty,
75 or if it's some sort of special file.
76 Any known file types appropriate to the system you are running on
77 (sockets, symbolic links, or named pipes (FIFOs) on those systems that
79 are intuited if they are defined in the system header file
82 The magic tests are used to check for files with data in
83 particular fixed formats.
84 The canonical example of this is a binary executable (compiled program)
86 file, whose format is defined in
91 in the standard include directory.
94 stored in a particular place
95 near the beginning of the file that tells the
98 that the file is a binary executable, and which of several types thereof.
101 has been applied by extension to data files.
102 Any file with some invariant identifier at a small fixed
103 offset into the file can usually be described in this way.
104 The information identifying these files is read from the compiled
107 or the files in the directory
109 if the compiled file does not exist.
114 exists, it will be used in preference to the system magic files.
116 If a file does not match any of the entries in the magic file,
117 it is examined to see if it seems to be a text file.
118 ASCII, ISO-8859-x, non-ISO 8-bit extended-ASCII character sets
119 (such as those used on Macintosh and IBM PC systems),
120 UTF-8-encoded Unicode, UTF-16-encoded Unicode, and EBCDIC
121 character sets can be distinguished by the different
122 ranges and sequences of bytes that constitute printable text
124 If a file passes any of these tests, its character set is reported.
125 ASCII, ISO-8859-x, UTF-8, and extended-ASCII files are identified
128 because they will be mostly readable on nearly any terminal;
129 UTF-16 and EBCDIC are only
132 they contain text, it is text that will require translation
133 before it can be read.
136 will attempt to determine other characteristics of text-type files.
137 If the lines of a file are terminated by CR, CRLF, or NEL, instead
138 of the Unix-standard LF, this will be reported.
139 Files that contain embedded escape sequences or overstriking
140 will also be identified.
144 has determined the character set used in a text-type file,
146 attempt to determine in what language the file is written.
147 The language tests look for particular strings (cf.
149 that can appear anywhere in the first few blocks of a file.
150 For example, the keyword
152 indicates that the file is most likely a
154 input file, just as the keyword
156 indicates a C program.
157 These tests are less reliable than the previous
158 two groups, so they are performed last.
159 The language test routines also test for some miscellany
164 Any file that cannot be identified as having been written
165 in any of the character sets listed above is simply said to be
168 .Bl -tag -width indent
170 Causes the file command to output the file type and creator code as
171 used by older MacOS versions. The code consists of eight letters,
172 the first describing the file type, the latter the creator.
173 .It Fl b , Fl Fl brief
174 Do not prepend filenames to output lines (brief mode).
175 .It Fl C , Fl Fl compile
178 output file that contains a pre-parsed version of the magic file or directory.
179 .It Fl c , Fl Fl checking-printout
180 Cause a checking printout of the parsed form of the magic file.
181 This is usually used in conjunction with the
183 flag to debug a new magic file before installing it.
185 On filesystem errors (file not found etc), instead of handling the error
186 as regular output as POSIX mandates and keep going, issue an error message
188 .It Fl e , Fl Fl exclude Ar testname
189 Exclude the test named in
191 from the list of tests made to determine the file type.
192 Valid test names are:
193 .Bl -tag -width compress
196 application type (only on EMX).
198 Various types of text files (this test will try to guess the text
199 encoding, irrespective of the setting of the
203 Different text encodings for soft magic tests.
205 Ignored for backwards compatibility.
207 Prints details of Compound Document Files.
209 Checks for, and looks inside, compressed files.
211 Prints ELF file details.
213 Consults magic files.
218 Print a slash-separated list of valid extensions for the file type found.
219 .It Fl F , Fl Fl separator Ar separator
220 Use the specified string as the separator between the filename and the
221 file result returned.
224 .It Fl f , Fl Fl files-from Ar namefile
225 Read the names of the files to be examined from
228 before the argument list.
231 or at least one filename argument must be present;
232 to test the standard input, use
234 as a filename argument.
237 is unwrapped and the enclosed filenames are processed when this option is
238 encountered and before any further options processing is done.
239 This allows one to process multiple lists of files with different command line
240 arguments on the same
243 Thus if you want to set the delimiter, you need to do it before you specify
244 the list of files, like:
245 .Dq Fl F Ar @ Fl f Ar namefile ,
247 .Dq Fl f Ar namefile Fl F Ar @ .
248 .It Fl h , Fl Fl no-dereference
249 option causes symlinks not to be followed
250 (on systems that support symbolic links).
251 This is the default if the environment variable
254 .It Fl i , Fl Fl mime
255 Causes the file command to output mime type strings rather than the more
256 traditional human readable ones.
258 .Sq text/plain; charset=us-ascii
261 .It Fl Fl mime-type , Fl Fl mime-encoding
264 but print only the specified element(s).
265 .It Fl k , Fl Fl keep-going
266 Don't stop at the first match, keep going.
267 Subsequent matches will be
271 (If you want a newline, see the
274 The magic pattern with the highest strength (see the
277 .It Fl l , Fl Fl list
278 Shows a list of patterns and their strength sorted descending by
281 which is used for the matching (see also the
284 .It Fl L , Fl Fl dereference
285 option causes symlinks to be followed, as the like-named option in
287 (on systems that support symbolic links).
288 This is the default if the environment variable
291 .It Fl m , Fl Fl magic-file Ar magicfiles
292 Specify an alternate list of files and directories containing magic.
293 This can be a single item, or a colon-separated list.
294 If a compiled magic file is found alongside a file or directory,
295 it will be used instead.
296 .It Fl N , Fl Fl no-pad
297 Don't pad filenames so that they align in the output.
298 .It Fl n , Fl Fl no-buffer
299 Force stdout to be flushed after checking each file.
300 This is only useful if checking a list of files.
301 It is intended to be used by programs that want filetype output from a pipe.
302 .It Fl p , Fl Fl preserve-date
303 On systems that support
307 attempt to preserve the access time of files analyzed, to pretend that
310 .It Fl P , Fl Fl parameter Ar name=value
311 Set various parameter limits.
312 .Bl -column "elf_phnum" "Default" "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" -offset indent
313 .It Sy "Name" Ta Sy "Default" Ta Sy "Explanation"
314 .It Li indir Ta 15 Ta recursion limit for indirect magic
315 .It Li name Ta 30 Ta use count limit for name/use magic
316 .It Li elf_notes Ta 256 Ta max ELF notes processed
317 .It Li elf_phnum Ta 128 Ta max ELF program sections processed
318 .It Li elf_shnum Ta 32768 Ta max ELF sections processed
321 Don't translate unprintable characters to \eooo.
324 translates unprintable characters to their octal representation.
325 .It Fl s , Fl Fl special-files
328 only attempts to read and determine the type of argument files which
330 reports are ordinary files.
331 This prevents problems, because reading special files may have peculiar
337 to also read argument files which are block or character special files.
338 This is useful for determining the filesystem types of the data in raw
339 disk partitions, which are block special files.
340 This option also causes
342 to disregard the file size as reported by
344 since on some systems it reports a zero size for raw disk partitions.
345 .It Fl v , Fl Fl version
346 Print the version of the program and exit.
347 .It Fl z , Fl Fl uncompress
348 Try to look inside compressed files.
349 .It Fl Z , Fl Fl uncompress-noreport
350 Try to look inside compressed files, but report information about the contents
351 only not the compression.
352 .It Fl 0 , Fl Fl print0
353 Output a null character
355 after the end of the filename.
359 This does not affect the separator, which is still printed.
361 Print a help message and exit.
364 .Bl -tag -width __MAGIC__.mgc -compact
366 Default compiled list of magic.
368 Directory containing default magic files.
371 The environment variable
373 can be used to set the default magic file name.
374 If that variable is set, then
376 will not attempt to open
381 to the value of this variable as appropriate.
384 has to exist in order for
387 The environment variable
389 controls (on systems that support symbolic links), whether
391 will attempt to follow symlinks or not.
394 follows symlink, otherwise it does not.
395 This is also controlled by the
401 .Xr magic __FSECTION__ ,
406 .Sh STANDARDS CONFORMANCE
407 This program is believed to exceed the System V Interface Definition
408 of FILE(CMD), as near as one can determine from the vague language
410 Its behavior is mostly compatible with the System V program of the same name.
411 This version knows more magic, however, so it will produce
412 different (albeit more accurate) output in many cases.
413 .\" URL: http://www.opengroup.org/onlinepubs/009695399/utilities/file.html
415 The one significant difference
416 between this version and System V
417 is that this version treats any white space
418 as a delimiter, so that spaces in pattern strings must be escaped.
420 .Bd -literal -offset indent
421 \*[Gt]10 string language impress\ (imPRESS data)
424 in an existing magic file would have to be changed to
425 .Bd -literal -offset indent
426 \*[Gt]10 string language\e impress (imPRESS data)
429 In addition, in this version, if a pattern string contains a backslash,
432 .Bd -literal -offset indent
433 0 string \ebegindata Andrew Toolkit document
436 in an existing magic file would have to be changed to
437 .Bd -literal -offset indent
438 0 string \e\ebegindata Andrew Toolkit document
441 SunOS releases 3.2 and later from Sun Microsystems include a
443 command derived from the System V one, but with some extensions.
444 This version differs from Sun's only in minor ways.
445 It includes the extension of the
449 .Bd -literal -offset indent
450 \*[Gt]16 long\*[Am]0x7fffffff \*[Gt]0 not stripped
453 The magic file entries have been collected from various sources,
454 mainly USENET, and contributed by various authors.
455 Christos Zoulas (address below) will collect additional
456 or corrected magic file entries.
457 A consolidation of magic file entries
458 will be distributed periodically.
460 The order of entries in the magic file is significant.
461 Depending on what system you are using, the order that
462 they are put together may be incorrect.
465 command uses a magic file,
466 keep the old magic file around for comparison purposes
468 .Pa __MAGIC__.orig ) .
470 .Bd -literal -offset indent
471 $ file file.c file /dev/{wd0a,hda}
472 file.c: C program text
473 file: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
474 dynamically linked (uses shared libs), stripped
475 /dev/wd0a: block special (0/0)
476 /dev/hda: block special (3/0)
478 $ file -s /dev/wd0{b,d}
480 /dev/wd0d: x86 boot sector
482 $ file -s /dev/hda{,1,2,3,4,5,6,7,8,9,10}
483 /dev/hda: x86 boot sector
484 /dev/hda1: Linux/i386 ext2 filesystem
485 /dev/hda2: x86 boot sector
486 /dev/hda3: x86 boot sector, extended partition table
487 /dev/hda4: Linux/i386 ext2 filesystem
488 /dev/hda5: Linux/i386 swap file
489 /dev/hda6: Linux/i386 swap file
490 /dev/hda7: Linux/i386 swap file
491 /dev/hda8: Linux/i386 swap file
495 $ file -i file.c file /dev/{wd0a,hda}
497 file: application/x-executable
498 /dev/hda: application/x-not-regular-file
499 /dev/wd0a: application/x-not-regular-file
506 .Dv UNIX since at least Research Version 4
507 (man page dated November, 1973).
508 The System V version introduced one significant major change:
509 the external list of magic types.
510 This slowed the program down slightly but made it a lot more flexible.
512 This program, based on the System V version,
513 was written by Ian Darwin
514 .Aq ian@darwinsys.com
515 without looking at anybody else's source code.
517 John Gilmore revised the code extensively, making it better than
519 Geoff Collyer found several inadequacies
520 and provided some magic file entries.
523 operator by Rob McMahon,
524 .Aq cudcv@warwick.ac.uk ,
529 made many changes from 1993 to the present.
532 Primary development and maintenance from 1990 to the present by
534 .Aq christos@astron.com .
536 Altered by Chris Lowth
537 .Aq chris@lowth.com ,
540 option to output mime type strings, using an alternative
541 magic file and internal logic.
543 Altered by Eric Fischer
546 to identify character codes and attempt to identify the languages
549 Altered by Reuben Thomas
551 2007-2011, to improve MIME support, merge MIME and non-MIME magic,
552 support directories as well as files of magic, apply many bug fixes,
553 update and fix a lot of magic, improve the build system, improve the
554 documentation, and rewrite the Python bindings in pure Python.
556 The list of contributors to the
558 directory (magic files)
559 is too long to include here.
560 You know who you are; thank you.
561 Many contributors are listed in the source files.
563 Copyright (c) Ian F. Darwin, Toronto, Canada, 1986-1999.
564 Covered by the standard Berkeley Software Distribution copyright; see the file
565 COPYING in the source distribution.
571 were written by John Gilmore from his public-domain
573 program, and are not covered by the above license.
576 returns 0 on success, and non-zero on error.
579 Please report bugs and send patches to the bug tracker at
580 .Pa http://bugs.gw.com/
581 or the mailing list at
584 .Pa http://mx.gw.com/mailman/listinfo/file
588 Fix output so that tests for MIME and APPLE flags are not needed all
589 over the place, and actual output is only done in one place.
591 Suggestion: push possible outputs on to a list, then pick the
592 last-pushed (most specific, one hopes) value at the end, or
593 use a default if the list is empty.
594 This should not slow down evaluation.
598 and printing \e012- between entries is clumsy and complicated; refactor
601 Some of the encoding logic is hard-coded in encoding.c and can be moved
602 to the magic files if we had a !:charset annotation
604 Continue to squash all magic bugs.
605 See Debian BTS for a good source.
607 Store arbitrarily long strings, for example for %s patterns, so that
608 they can be printed out.
609 Fixes Debian bug #271672.
610 This can be done by allocating strings in a string pool, storing the
611 string pool at the end of the magic file and converting all the string
612 pointers to relative offsets from the string pool.
614 Add syntax for relative offsets after current level (Debian bug #466037).
616 Make file -ki work, i.e. give multiple MIME types.
618 Add a zip library so we can peek inside Office2007 documents to
619 print more details about their contents.
621 Add an option to print URLs for the sources of the file descriptions.
623 Combine script searches and add a way to map executable names to MIME
624 types (e.g. have a magic value for !:mime which causes the resulting
625 string to be looked up in a table).
626 This would avoid adding the same magic repeatedly for each new
627 hash-bang interpreter.
629 When a file descriptor is available, we can skip and adjust the buffer
630 instead of the hacky buffer management we do now.
636 to check for consistency at compile time (duplicate
639 pointing to undefined
646 more efficient by keeping a sorted list of names.
647 Special-case ^ to flip endianness in the parser so that it does not
648 have to be escaped, and document it.
650 If the offsets specified internally in the file exceed the buffer size
653 variable in file.h), then we don't seek to that offset, but we give up.
654 It would be better if buffer managements was done when the file descriptor
655 is available so move around the file.
656 One must be careful though because this has performance (and thus security
659 You can obtain the original author's latest version by anonymous FTP
663 .Pa /pub/file/file-X.YZ.tar.gz .