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NAME    [Toc]    [Back]

       file, jfile - Determines file type

SYNOPSIS    [Toc]    [Back]

       file [-c] [-f file_list] [-m magic_file] file...

STANDARDS    [Toc]    [Back]

       Interfaces  documented  on  this reference page conform to
       industry standards as follows:

       file:  XCU5.0

       Refer to the standards(5) reference page for more information
 about industry standards and associated tags.

OPTIONS    [Toc]    [Back]

       [Tru64   UNIX]  Checks   the  magic  file  (/etc/magic  by
       default) for format errors.  This validation is  not  normally
  done.   File  typing  is  not done under this flag.
       [Tru64 UNIX]  Reads file_list for a list of files to examine.
  [Tru64 UNIX]  Specifies magic_file as the magic file
       (/etc/magic by default).

OPERANDS    [Toc]    [Back]

       The path name of the file to be tested.

DESCRIPTION    [Toc]    [Back]

       The file command reads input files and performs  a  series
       of tests on each one. It then attempts to classify them by
       type and writes the file types to standard output.

       The file command uses  the  /etc/magic  file  to  identify
       files  that have some sort of a magic number (that is, any
       file containing a numeric or string  constant  that  indicates
 its type).

       The  file command returns a number of hard and soft errors
       for character special files.

       [Tru64 UNIX]   If you run a file  command  on  /proc  file
       system it produces unpredictable results.

       [Tru64  UNIX]  If  a  file  appears to be plain text, file
       examines the first 512 bytes and tries to  determine  what
       kind  of  text it is.  If the first 512 bytes only contain
       ASCII  characters,  file  returns  either  ascii  text  or
       English text.  If the file contains other characters (that
       is, European or  Asian  extended  characters),  file  uses
       checks  as described in the section titled "Internationalization
 and Localization  Enhancements"  to  evaluate  the
       encoding.   The  jfile  command alias, which enables filetesting
 logic that is Japanese specific  even  for  the  C
       locale, is also described in this section.

       [Tru64  UNIX]  If a file does not appear to be plain text,
       file attempts to distinguish a binary  data  file  from  a
       text  file that contains extended characters.  If the file
       is an a.out file and the version number  is  greater  than
       zero, file displays the version stamp.

       [Tru64  UNIX]  For  character  special  files, part of the
       identification is information about the devices the system
       shows  as  active. In particular, file returns device-specific
 information such as controller type and unit, device
       type and unit, and status (offline, write locked, density,
       errors).  The general categories currently implemented are
       disk,  tape,  and terminal devices. The supported terminal
       devices include Local Area Terminals (LAT) but  not  Local
       Area Network (LAN) pseudo-terminals.

       [Tru64  UNIX]  The  following  example  shows how the file
       command identifies a device. The output is  shown  on  two
       lines due to space considerations, but appears on one line
       on a display.  # file /dev/rdisk/dsk17c

       /dev/rdisk/dsk17c:  character  special  (19/86)  SCSI   #1
       "RZ26L" disk #4 (SCSI ID #1) (SCSI LUN #0) errors = 1/4

       In  this  example,  the  device reports 1 soft error and 4
       hard errors.  All errors should be  logged  in  the  error

       The  following  example  shows  a device with no errors: #
       file /dev/rdisk/dsk18c

       /dev/rdisk/dsk18c:  character  special  (19/326)  SCSI  #1
       "RZ26L" disk #5 (SCSI ID #2) (SCSI LUN #0)

       [Tru64 UNIX]  On Tru64 UNIX systems, the file command recognizes
 OSF core files.  For example: # file core

       core:   core dump, generated from 'mwm'

       [Tru64 UNIX]  The amount and type of information the  file
       command  returns can depend on the permissions of the file
       being queried. For example, most special device files have
       permissions  that  allow  access only by root and non-root
       users cannot open them. The file command has to  open  the
       device and only root has the proper permissions.  Thus, if
       the file command is issued by  a  non-root  user,  it  can
       report  only  information it can determine without gaining
       access to the device.

       [Tru64 UNIX]  The file command also uses  internal  tables
       to  decode  certain  types of files. The following example
       shows the keywords the file command uses to locate  troff,
       C code, and assembler code.

       char  *troff[] = {    /* new troff intermediate lang */
             "x","T","res","init","font","202","V0","p1",0}; char
       *c[] = {
       char  *as[] = {

       The  file  types  recognized  and identification displayed
       include those shown in the following table:

       If file is                             It is identified as
       directory                              directory
       FIFO                                   fifo
       block special                          block special
       compressed crash dump                  compressed memory image (dump) file
       character special                      character special

       executable binary                      executable
       empty regular file                     empty
       ar archive library (see ar)            archive
       extended cpio format (see pax)         cpio archive
       extended tar format (see tar)          tar archive
       shell script                           commands text
       C-language source                      c program text
       FORTRAN source                         fortran program text
       audio file (.voc, .iff, .wav)          audio
       image file (TIFF, GIF, MPEG, JPEG)     image
       PKZIP format                           zip archive
       GZIP format                            gzip compressed data

   Internationalization and Localization Enhancements    [Toc]    [Back]
       [Tru64 UNIX]  The  file  command  includes  the  following
       enhancements  for  identifying a text file: In any locale,
       the file command uses the presence of the byte-order  mark
       to  recognize  ISO10646/Unicode  encoding (UCS-2 and UCS-4
       formats).  In any locale, the file command checks  whether
       the  characters  in  the file are valid for the codeset of
       the current locale.  When the jfile  alias  for  the  file
       command  is  used  or  if  the file command is used in any
       Japanese locale, the command uses specialized  text-detection
  logic to determine whether the character encoding is
       one of the following: DEC Kanji  Japanese  EUC  Shift  JIS
       7-bit  JIS  (for example, ISO-2022-JP) If the text file is
       not identified by the ascii text or English text  message,
       the  message  states whether the text contains single-byte
       or multibyte characters and which codeset  the  characters
       belong to. In other words, the message that identifies the
       file would use one of the  following  formats:  multi-byte
       text (codeset-name)

              single-byte text (codeset-name)

              If  the file command does not identify the encoding
              of a text file, the displayed message  is  data  or
              International Language text.

RESTRICTIONS    [Toc]    [Back]

       [Tru64  UNIX]  The  file  command often does a poor job of
       distinguishing C programs, shell  scripts,  English  text,
       and  ASCII  text.  In addition, it does not recognize certain
 programming languages, including Modula, Pascal,  and

EXIT STATUS    [Toc]    [Back]

       The following exit values are returned: Successful completion.
  An error occurred.

EXAMPLES    [Toc]    [Back]

       To display the type of information a file contains, enter:
       file myfile

              This  displays  the file type of myfile (directory,
              data, ASCII text, C program source, archive, and so
              on).   To  display the type of each file named in a
              list of file names, enter: file -f filenames

              This displays the type of each  file  with  a  name
              that  appears  in  filenames.   Each file name must
              appear alone on a line.

              To create filenames, enter: ls > filenames

              Then edit filenames as desired.

FILES    [Toc]    [Back]

       File type database

SEE ALSO    [Toc]    [Back]

       Commands:  ar(1), cpio(1), ls(1), pax(1), tar(1)

       Files:  magic(4)

       Standards:  standards(5)

       Programmer's Guide

[ Back ]
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