Determine file type.
Syntax
file [-bchikLNnprsvz0] [--apple] [--mime-encoding] [--mime-type] [-e testname]
[-F separator] [-f namefile] [-m magicfiles] file ...
file -C [-m magicfiles]
file [--help]
Key
-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 flag to debug a
new magic file before installing it.
-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).
text 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 Looks for known tokens inside text files.
cdf Prints details of Compound Document Files.
compress Checks for, and looks inside, compressed files.
elf Prints ELF file details.
soft Consults magic files.
tar Examines tar files.
-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.
-h, --no-dereference
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 might say 'text/plain; charset=us-ascii'
rather than 'ASCII text'. In order 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
have the string '\012- ' prepended. (If you want a newline, see -r)
-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 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(2) or utimes(2), attempt to preserve
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 can 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.
-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.
file returns 0 on success, and non-zero on error.
If the file named by the file operand does not exist, cannot be read, or the type of the file named by the file operand cannot be determined, this is not be considered an error that affects the exit status.
Examples
$ 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
file uses several algorithms that favor speed over accuracy, thus it can be misled about the contents of text files.
#Dance to this fix and flex every muscle
Space can be filled if you rise like my lumber
Advance to the tune but don't do the hustle
Shake, rattle, roll to my magic number# ~ De La Soul (The Magic Number)
Related linux commands:
magic(5), strings(1), od(1), hexdump(1,) file(1posix)
The famous Tuesday bug in file - Cannot print on Tuesdays.