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       typerules - HylaFAX file type identification and conversion rules


       Only  three  types  of  files  are  accepted  by  the  HylaFAX  server for transmission as
       facsimile: POSTSCRIPT® files, PDF files, and TIFF Class F (bilevel Group 3-encoded) files.
       All  other  types of files must be converted to one of these three formats.  The facsimile
       submission program applies a set of rules against the  contents  of  each  input  file  to
       identify  the  file's  type  and to figure out how to convert the file to a format that is
       suitable for transmission.  These rules are stored in the file /etc/hylafax/typerules,  an
       ASCII  file  that  is  patterned  after  the  /etc/magic file used by the System V file(1)
       program.  However, there are significant differences, noted below.

       Type rules work by matching data patterns in a file; typically patterns that appear in the
       first  few bytes of the file (i.e.  magic numbers).  There are two types of rules, primary
       rules and secondary rules.  Secondary rules specify additional  rules  to  apply  after  a
       primary  rule has been matched.  When secondary rules are used, rule scanning continues up
       to the next primary type rule in the file.

       Each rule consists of a set of whitespace-separated fields:
            offset    datatype    match    result   command
       If an line is terminated wth a backslash character, the entry is  continued  on  the  next
       line  with  any  leading whitespace characters compressed to a single space.  Comments are
       marked with the ``#'' character; everything from to the end  of  the  line  is  discarded.
       Secondary  rules  have a ``>'' character in the first column of the line; primary rules do

       The fields in each rule entry are:

       offset    The byte offset in the file at which data should be extracted and compared to  a
                 matching string or value.

       datatype  The  type  of  data  value  to  extract  at  the specified offset for comparison
                 purposes; one of: ``byte'' (8 bit unsigned number), ``short'' (16  bit  unsigned
                 number),  ``long''  (32  bit  unsigned  number), ``string'' (an array of bytes),
                 ``istring'' (a case-insensitive array of  bytes),  or  ``ascii''  (an  array  of
                 ASCII-only bytes).

       match     The  value  and  operation  to  use  in matching; the value used is based on the
                 datatype field.  If value is  ``x'',  then  it  is  interpreted  to  mean  match
                 anything;  otherwise  the  following  operators are supported (where data is the
                 value extracted from the file and value is specified in the match field)  except
                 for types ``string'', ``istring'', and ``ascii'':
                 =     data == value              !=    data != value
                 >     data > value               <     data < value
                 <=    data <= value              >=    data >= value
                 &     (data & value) == value    !     (data & value) != value
                 ^     (data ^ value) != 0

       If no operation is specified then ``='' is used.

       For ``string'', ``istring'', and ``ascii'' no operator is allowed; the implicit
       operation is always ``=''.  In these cases, the field is terminated by
       a tab or end of line, not by ``#''.  Characters in the field have
       their literal value; there are no C-style character escapes.

       result    One of ``ps'', ``tiff'', or ``error'' (case insensitive).  The first two results
                 specify whether the rule generates a POSTSCRIPT file or  a  TIFF/F  file  (Group
                 3-encoded  bilevel  data),  respectively.  The ``error'' result indicates that a
                 file is unsuitable for transmission and, if supplied  for  transmission,  should
                 cause the job to be aborted with the command field used in an error message.

       command   A  command  description  that is expanded and passed to the shell to convert the
                 input file to the result format (suitable for sending as facsimile).  Before the
                 string  is  passed  to  the  shell, it is scanned and the following ``%'' escape
                 codes are substituted for:
                 %i      input file name
                 %o      output file name
                 %r      output horizontal resolution in pixels/mm
                 %R      output horizontal resolution in pixels/inch
                 %v      output vertical resolution in lines/mm
                 %V      output vertical resolution in lines/inch
                 %f      data format, ``1'' for 1-d encoding or ``2'' for 2-d encoding
                 %w      page width in pixels
                 %W      page width in mm
                 %l      page length in pixels
                 %L      page length in mm
                 %s      page size by name
                 %F      the directory where HylaFAX filter programs reside
                 %<x>    the <x> character (e.g. ``%%'' results in ``%''
       See below for example uses of these codes.


       The following rules are used to match the formats that are handled directly by the server:
       #offset   datatype    match          result    command
       0         string      %!             ps                       # POSTSCRIPT
       0         string      %PDF           ps                       # POSTSCRIPT by Ghostscript
       0         short       0x4d4d         tiff                     # big-endian TIFF
       0         short       0x4949         tiff                     # little-endian TIFF

       These rules are used to process the ASCII version of IRIS Inventor  database  files  while
       blocking the transmission of the binary format variant:
       #offset   datatype    match          result    command
       0         string      #Inventor V    error     IRIS Inventor file
       >15       string      binary         error     binary IRIS Inventor file
       >15       string      ascii          ps        %F/textfmt -fCourier-Bold -p11bp\
                                                          -U -q >%o <%i

       This  rule  is  typically  the last entry in the file and is used to convert all unmatched
       ASCII data files to POSTSCRIPT:
       #offset   datatype    match          result    command
       0         ascii       x              ps        %F/textfmt -fCourier-Bold -p11bp -U -q >%o <%i


       It is much better to convert data that is to be transmitted  to  POSTSCRIPT  because  this
       data  format permits the facsimile server to do the final imaging according to the optimal
       transfer parameters (resolution, binary encoding, etc.).

       It might be better to allow secondary rules to augment a primary  rule  rather  than  just
       replace them.  This would allow, for example, command line options to be selected based on
       file type.


       sendfax(1), hylafax-client(1)

                                           May 12, 1993                              TYPERULES(5)