manpagez: man pages & more
man file(1)
Home | html | info | man
file(1)                     General Commands Manual                    file(1)


     file - determine file type


     file [-bcdEhiklLNnprsSvzZ0] [--apple] [--exclude-quiet] [--extension]
          [--mime-encoding] [--mime-type] [-e testname] [-F separator]
          [-f namefile] [-m magicfiles] [-P name=value] file ...
     file -C [-m magicfiles]
     file [--help]


     This manual page documents version 5.45 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
     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 /opt/local/share/misc/magic.mgc, or the
     files in the directory /opt/local/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
     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 files).

     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.

     -d      Prints internal debugging information to stderr.

     -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.

             simh      Examines SIMH tape files.

             tar       Examines tar files by verifying the checksum of the 512
                       byte tar header.  Excluding this test can provide more
                       detailed content description by using the soft magic

             text      A synonym for `ascii'.

             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 found.

     -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).  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".

     --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 if the environment variable POSIXLY_CORRECT is

     -m, --magic-file magicfiles
             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-pad
             Don't pad filenames so that they align in the output.

     -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 them.

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

             Name         Default    Explanation
             bytes        1M         max number of bytes to read from file
             elf_notes    256        max ELF notes processed
             elf_phnum    2K         max ELF program sections processed
             elf_shnum    32K        max ELF sections processed
             elf_shsize   128MB      max ELF section size processed
             encoding     65K        max number of bytes to determine encoding
             indir        50         recursion limit for indirect magic
             name         50         use count limit for name/use magic
             regex        8K         length limit for regex searches

     -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
             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.

     -S, --no-sandbox
             On systems where libseccomp
             ( is available, the -S
             option disables sandboxing which is enabled by default.  This
             option is needed for file to execute external decompressing
             programs, i.e. when the -z option is specified and the built-in
             decompressors are not available.  On systems where sandboxing is
             not available, this option has no effect.

     -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.

             If this option is repeated more than once, then file prints just
             the filename followed by a NUL followed by the description (or
             ERROR: text) followed by a second NUL for each entry.

     --help  Print a help message and exit.


     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
     appropriate.  The environment variable POSIXLY_CORRECT controls (on
     systems that support symbolic links), whether 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.


     /opt/local/share/misc/magic.mgc  Default compiled list of magic.
     /opt/local/share/misc/magic      Directory containing default magic


     file will exit with 0 if the operation was successful or >0 if an error
     was encountered.  The following errors cause diagnostic messages, but
     don't affect the program exit code (as POSIX requires), unless -E is
           o   A file cannot be found
           o   There is no permission to read a file
           o   The file type cannot be determined


           $ 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


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


     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
     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


     On systems where libseccomp ( is
     available, file is enforces limiting system calls to only the ones
     necessary for the operation of the program.  This enforcement does not
     provide any security benefit when file is asked to decompress input files
     running external programs with the -z option.  To enable execution of
     external decompressors, one needs to disable sandboxing using the -S


     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


     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

     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.


     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 repeatedly 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 13.5                       May 21, 2023                       macOS 13.5

file 5.45 - Generated Thu Aug 17 12:55:14 CDT 2023
© 2000-2024
Individual documents may contain additional copyright information.