File

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: Look for known tokens inside text files.
  • cdf: Print details of Compound Document Files.
  • compress: Check for, and looks inside, compressed files.
  • elf: Print ELF file details.
  • soft: Consult magic files.
  • tar: Examine 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.

• --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 (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.

Files

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

Return Code

• 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 considered an error that affects the exit status.
• file uses several algorithms that favor speed over accuracy, thus it can be misled about the contents of text files.

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