FILE(1)                      General Commands Manual                     FILE(1)

     file – determine file type

     file [-bcdDhiIkLnNprsvz] [--exclude-quiet] [--extension] [--mime-encoding]
          [--mime-type] [-f namefile] [-m magicfiles] [-P name=value]
          [-M magicfiles] file
     file -C [-m magicfiles]
     file [--help]

     This manual page documents version 5.04 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

     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 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 modifying
     magic files or the program itself, make sure to preserve these keywords.
     Users depend on knowing that all the readable files in a directory 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 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 <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 executable,
     and which of several types thereof.  The concept of a “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 identifying these files is read from the
     compiled magic file /usr/share/file/magic.mgc, or the files in the
     directory /usr/share/file/magic if the compiled file does not exist.

     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 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” 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 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 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) archives, JSON

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

             Causes the file command to output the file type and creator code as
             used by older MacOS versions.  The code consists of eight letters,
             the first describing the file type, the latter the creator.  This
             option works properly only for file formats that have the apple-
             style output defined.

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

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

     -c, --checking-printout
             Cause a checking printout of the parsed form of the magic file.
             This is usually used in conjunction with the -m option 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.

     -d      Apply the default system tests; this is the default behavior unless
             -M is specified.

     -D      Print debugging messages.

     -E      On filesystem errors (file not found etc), instead of handling the
             error as regular output as POSIX mandates and keep going, issue an
             error message and exit.

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

             apptype   EMX application type (only on EMX).

             ascii     Various types of text files (this test will try to guess
                       the text encoding, irrespective of the setting of the
                       ‘encoding’ option).

             encoding  Different text encodings for soft magic tests.

             tokens    Ignored for backwards compatibility.

             cdf       Prints details of Compound Document Files.

             compress  Checks for, and looks inside, compressed files.

             csv       Checks Comma Separated Value files.

             elf       Prints ELF file details, provided soft magic tests are
                       enabled and the elf magic is found.

             json      Examines JSON (RFC-7159) files by parsing them for

             soft      Consults magic files.

             tar       Examines tar files.

             Like --exclude but ignore tests that file does not know about.
             This is intended for compatibility with older versions of file.

             Print a slash-separated list of valid extensions for the file type

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

     -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.  Please note that namefile is unwrapped
             and the enclosed filenames are processed when this option is
             encountered and before any further options processing is done.
             This allows one to process multiple lists of files with different
             command line arguments on the same file invocation.  Thus if you
             want to set the delimiter, you need to do it before you specify the
             list of files, like: “-F @ -f namefile”, instead of: “-f namefile
             -F @”.

     -h, --no-dereference
             This option causes symlinks not to be followed (on systems that
             support symbolic links).

     -i      If the file is a regular file, do not classify its contents.

     -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”.

     --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 newline, see
             the -r option.)  The magic pattern with the highest strength (see
             the -l option) comes first.

     -l, --list
             Shows a list of patterns and their strength sorted descending by
             magic(5) strength which is used for the matching (see also the -k

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

     -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.

     -M list
             Like -m, except that the default rules are not applied unless -d is

     -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.

     -p, --preserve-date
             On systems that support utime(3) or utimes(2), attempt to preserve
             the access time of files analyzed, to pretend that file never read

     -P, --parameter name=value
             Set various parameter limits.

                   Name         Default    Explanation
                   bytes        1048576    max number of bytes to read from file
                   elf_notes    256        max ELF notes processed
                   elf_phnum    2048       max ELF program sections processed
                   elf_shnum    32768      max ELF sections processed
                   encoding     65536      max number of bytes to scan for
                                           encoding evaluation
                   indir        50         recursion limit for indirect magic
                   name         60         use count limit for name/use magic
                   regex        8192       length limit for regex searches

     -r, --raw
             No operation, included for historical compatibility.

     -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 peculiar
             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.

     -Z, --uncompress-noreport
             Try to look inside compressed files, but report information about
             the contents only not the compression.

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

     The environment variable MAGIC can be used to set the default magic file
     name.  file adds “.mgc” to the value of this variable as appropriate.
     However, file has to exist in order for file.mime to be considered.

     In legacy mode, the -D, -I, and -M options do not exist.

     The -d, -i, and -r options behave differently.  The -d option provides
     debugging information (same as -D in conformance mode).  The -i option
     displays mime type information (same as -I in conformance mode).  The -r
     option will disable the translation of unprintable characters (by default,
     this translation is already disabled in conformance mode).

     Furthermore, the -h option becomes the default symlink behavior (don't
     follow symlinks) unless POSIXLY_CORRECT is set.

     For more information about legacy mode, see compat(5).

     hexdump(1), od(1), strings(1), magic(5), otool(1), compat(5)

     This program conforms to Version 3 of the Single UNIX Specification
     (“SUSv3”).  Its behavior 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 command
     derived from the System V one, but with some extensions.  This version
     differs 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
     below) will collect additional or corrected magic file entries.  A
     consolidation 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
     incorrect.  If your old file command uses a magic file, keep the old magic
     file around for comparison purposes (rename it to

           $ 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 introduced 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 of the ‘&’ operator by Rob McMahon,
     ⟨⟩, 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 character
     codes and attempt to identify the languages of non-ASCII files.

     Altered by Reuben Thomas ⟨⟩, 2007-2011, to improve MIME
     support, merge MIME and non-MIME magic, support directories as well as
     files of magic, apply many bug fixes, update and fix a lot of magic,
     improve the build system, improve the documentation, and rewrite the Python
     bindings in pure Python.

     The list of contributors to the ‘magic’ directory (magic files) is too long
     to include here.  You know who you are; thank you.  Many contributors 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 COPYING in
     the source distribution.

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

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

     Please report bugs and send patches to the bug tracker at or the mailing list at ⟨⟩ (visit first to subscribe).

     Fix output so that tests for MIME and APPLE flags are not needed all over
     the place, and actual output is only done in one place.  This needs a
     design.  Suggestion: push possible outputs on to a list, then pick the
     last-pushed (most specific, one hopes) value at the end, or use a default
     if the list is empty.  This should not slow down evaluation.

     The handling of MAGIC_CONTINUE and printing \012- between entries is clumsy
     and complicated; refactor and centralize.

     Some of the encoding logic is hard-coded in encoding.c and can be moved to
     the magic files if we had a !:charset annotation.

     Continue to squash all magic bugs.  See Debian BTS for a good source.

     Store arbitrarily long strings, for example for %s patterns, so that they
     can be printed out.  Fixes Debian bug #271672.  This can be done by
     allocating strings in a string pool, storing the string pool at the end of
     the magic file and converting all the string pointers to relative offsets
     from the string pool.

     Add syntax for relative offsets after current level (Debian bug #466037).

     Make file -ki work, i.e. give multiple MIME types.

     Add a zip library so we can peek inside Office2007 documents to print more
     details about their contents.

     Add an option to print URLs for the sources of the file descriptions.

     Combine script searches and add a way to map executable names to MIME types
     (e.g. have a magic value for !:mime which causes the resulting string to be
     looked up in a table).  This would avoid adding the same magic repeatedly
     for each new hash-bang interpreter.

     When a file descriptor is available, we can skip and adjust the buffer
     instead of the hacky buffer management we do now.

     Fix “name” and “use” to check for consistency at compile time (duplicate
     “name”, “use” pointing to undefined “name” ).  Make “name” / “use” more
     efficient by keeping a sorted list of names.  Special-case ^ to flip
     endianness in the parser so that it does not have to be escaped, and
     document it.

     If the offsets specified internally in the file exceed the buffer size (
     HOWMANY variable in file.h), then we don't seek to that offset, but we give
     up.  It would be better if buffer managements was done when the file
     descriptor is available so we can seek around the file.  One must be
     careful though because this has performance and thus security
     considerations, because one can slow down things by repeateadly seeking.

     There is support now for keeping separate buffers and having offsets from
     the end of the file, but the internal buffer management still needs an

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

macOS 12.1                      February 5, 2021                      macOS 12.1