file(1) 						      General Commands Manual							   file(1)

NAME

       file, jfile - Determines file type

SYNOPSIS

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

STANDARDS

       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

       [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

       The path name of the file to be tested.

DESCRIPTION

       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 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 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  par-
       ticular,  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 consider-
       ations, but appears on one line on a display.  % file /dev/rdisk/dsk0c

       /dev/rdisk/dsk0c: character special (8/2) SCSI #0 RZ24 disk #0 (SCSI ID #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[] = {
	     "int","char","float","double","struct","extern",0}; char  *as[] = {
	     "globl","byte","align","text","data","comm",0};

       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
       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 code-
       set 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

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

EXIT STATUS

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

EXAMPLES

       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

       File type database

SEE ALSO

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

       Files:  magic(4)

       Standards:  standards(5)

       Programmer's Guide

																	   file(1)