File man page on DigitalUNIX

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file(1)								       file(1)

       file, jfile - Determines file type

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

       Interfaces  documented on this reference page conform to industry stan‐
       dards as follows:

       file:  XCU5.0

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

       [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).

       The path name of the file to be tested.

       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  pro‐
       duces 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 file-testing 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 num‐
       ber 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 partic‐
       ular, file returns device-specific information such as controller  type
       and unit, device type and unit, and status (offline, write locked, den‐
       sity, 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-ter‐

       [Tru64  UNIX]  The following example shows how the file command identi‐
       fies a device. The output is shown on two lines due to space considera‐
       tions, 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 log.

       The   following	 example  shows	 a  device  with  no  errors:  #  file

       /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 cer‐
       tain  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[] = {
	     "int","char","float","double","struct","extern",0}; 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
       [Tru64 UNIX]  The file command includes the following enhancements  for
       identifying a text file: In any locale, the file command uses the pres‐
       ence 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 (code‐

	      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

       [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 Lisp.

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

       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

	      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.

       File type database

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

       Files:  magic(4)

       Standards:  standards(5)

       Programmer's Guide


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