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gnome-vfs-mime-magic.4(4)		   File Formats 		gnome-vfs-mime-magic.4(4)

       gnome-vfs-mime-magic, gnome-vfs.mime, gnome-vfs.keys - GNOME VFS MIME detection

       GnomeVFS is obsolete.  Refer to the GNOME Desktop System Administration Guide for informa-
       tion about how to register MIME type information with the GNOME desktop.  The GNOME  Desk-
       top System Administration Guide can be viewed with yelp(1).

       On any modern desktop system, each document type or file type must be given a unique iden-
       tification name and icon. In GNOME, this information is used extensively by the file  man-
       ager,  nautilus(1).  The  primary  underlying  mechanism for providing such definitions is
       achieved via gnome-vfs-mime-magic. gnome-vfs-mime-magic contains the default file  content
       sniffers  for  identifying  MIME  types.  The  concept of MIME magic is similar to that of
       Solaris magic(4).

       Each line in the /etc/gnome/gnome-vfs-mime-magic file describes a MIME type. The format of
       each line is as follows:

       offset_start[:offset_end] pattern_type pattern  [&pattern_mask] mime-type

       Each line contains the following fields:

       offset_start	       Decimal	number	that, with offset_end, specifies the bytes offset
			       within the file.

       offset_end	       Decimal number that, with offset_start, specifies the bytes offset
			       within the file.

       pattern_type	       Can be one of the following types:

			       byte  | short | long | string | date | beshort | belong | bedate |
			       leshort | lelong | ledate

			       where be stands for Big Endian and le stands for Little Endian.

       pattern		       An ASCII string with non-printable characters escaped  as  hex  or
			       octal  escape sequences, and spaces and other important whitespace
			       escaped with a backslash (\).

       pattern_mask	       A string of hex digits. The mask must be the same specification as
			       the non-ambiguous patterns.

       mime-type	       A valid MIME type.

       The  magic patterns are matched sequentially from the first entry to the last entry of the
       list. Therefore, you should put the non-ambiguous patterns at the start of the  list.  Any
       pattern that requires a deep seek into the file should be placed at the end of the list to
       reduce performance overhead.  When designing new document formats, include an easily  rec-
       ognizable  unique  magic pattern near the start of the file. A good pattern is is at least
       four bytes long and contains one or two non-printable characters so that  text  files  are
       not misidentified.

       and gnome-vfs.keys"

       Apart  from  file  sniffing,  GNOME  also  provide a secondary mechanism to determine MIME
       types. If a file has been sniffed and its type does not match any of the  magic	patterns,
       GNOME  looks  for  files called /usr/share/gnome/mime-info/*.mime and processes these. The
       format of these files is different to that of pattern magic. Instead  of  determining  the
       MIME  type  by reading the content of the file, the MIME type of the file is determined by
       its extension.  The mime info file has the following format:

	   ext[,prio]: list of extensions for this mime-type
	   regex[,prio]: regular expression that matches the filename

       More than one ext: and regex: field can be present for a given MIME type. You can also as-
       sociate	a  priority  for each field. The default priority (prio) is 1, a higher numerical
       value indicates a higher priority. The indentation before ext: and regex: must  be  a  tab
       character (\t).

       The  searching  sequence  implies that the magic pattern file has a higher precedence over
       the mime info files. As the mime info files are read	alphabetically, this also  deter-
       mines matching orders for the file extension.

       For example, the file FirstFile.mime contains the following definition:

	   ext: foo

       and the file SecondFile.mime contains the following definition:

	   ext: foo

       The definition in FirstFile.mime will be found first and used.

       For  each  MIME info file there must be an associated keys file in the same directory. The
       key file provides human readable text which can be localized into various  languages.  The
       data in these keys files is used by the GNOME file manager, nautilus(1).

       Example 1: Magic pattern definition for PDF file

       The following entry in the /etc/gnome/gnome-vfs-mime-magic file describes the MIME type of

	    0	 string    %PDF-		    application/pdf

       The first 5 characters of a PDF file are %PDF-. The symbols % and - differentiate the  PDF
       file from a text file.

       Example 2: Magic pattern definition for BMP file

       The following entry in the /etc/gnome/gnome-vfs-mime-magic file describes the MIME type of

       0    string	   BMxxxx 00 00 &0xffff00000000ffff   image/bmp

       The interpretation of this line is as follows:

	 o  The first two characters are BM and the seventh and eighth characters are NULL.

	    The mask 0xffff00000000ffff allows the selction of the first,  second,  seventh,  and
	    eighth characters to be selected for comparison.

       Example 3: MIME info file definition for application/x-compress

       The following entry in the /etc/gnome/gnome-vfs-mime-magic file describes the MIME type of

		 ext: Z

       This line indicates that the x-compress application searches for files with  a  .Z  exten-

       The  associated keys file entry in the /usr/share/gnome/mime-info/gnome-vfs.mime      file
       is as follows (excluding all localized text):

		 description=compress-compressed file

       Example 4: MIME info file definition for application/x-compressed-tar

       The following entry in the /etc/gnome/gnome-vfs-mime-magic file describes the MIME type of

		      regex,2: tar.gz$
		      ext: tgz

       This  example uses the priority flag to give regex a higher priority than ext, which means
       that a file with an extension of tar.gz should be matched first (to have a  MIME  type  of
       application/x-compressed-tar) before tgz.

       The following files are used by this application:






       See attributes(5) for descriptions of the following attributes:

       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       |Availability		     |SUNWgnome-vfs		   |
       |Interface stability	     |Obsolete Volatile 	   |

       nautilus(1), gnome-vfs.applications(4), libgnomevfs-2(3), gnome-interfaces(5)

       Latest version of the GNOME Desktop System Administration Guide for your platform.

       Written by Ghee Teo, Sun Microsystems Inc., 2003.

SunOS 5.11				   14 May 2008			gnome-vfs-mime-magic.4(4)
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