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mailcap (4)
  • >> mailcap (4) ( Solaris man: Специальные файлы /dev/* )
  • mailcap (4) ( Linux man: Специальные файлы /dev/* )
  • mailcap (5) ( Linux man: Форматы файлов )
  • 
    NAME
         mailcap - metamail capabilities file
    
    DESCRIPTION
         The mailcap file is read by the metamail program  to  deter-
         mine how to display non-text at the local site.
    
         The syntax of a mailcap file is quite simple, at least  com-
         pared  to termcap files.  Any line that starts with "#" is a
         comment.  Blank lines are  ignored.   Otherwise,  each  line
         defines  a  single  mailcap entry for a single content type.
         Long lines may be continued by ending them with a  backslash
         character, \.
    
         Each individual mailcap entry  consists  of  a  content-type
         specification, a command to execute, and (possibly) a set of
         optional "flag" values.  For example, a very simple  mailcap
         entry  (which  is  actually  a built-in default behavior for
         metamail) would look like this:
    
         text/plain; cat %s
    
         The optional flags can be used to specify additional  infor-
         mation about the mail-handling command.  For example:
    
         text/plain; cat %s; copiousoutput
    
         can be used to indicate that the output of the 'cat' command
         may  be  voluminous,  requiring either a scrolling window, a
         pager, or some other appropriate coping mechanism.
    
         The "type" field (text/plain, in the above example) is  sim-
         ply  any legal content type name, as defined by RFC 822.  In
         practice, this is almost any string.  It is the string  that
         will  be  matched  against the "Content-type" header (or the
         value passed in with -c) to decide if this  is  the  mailcap
         entry  that  matches the current message.  Additionally, the
         type field may specify a subtype (e.g. "text/ISO-8859-1") or
         a wildcard to match all subtypes (e.g. "image/*").
    
         The "command" field is any UNIX command  ("cat  %s"  in  the
         above  example),  and is used to specify the interpreter for
         the given type of message.  It will be passed to  the  shell
         via  the  system(3)  facility.   Semicolons  and backslashes
         within the command must be quoted with backslashes.  If  the
         command contains "%s", those two characters will be replaced
         by the name of a file that contains the body of the message.
         If  it  contains "%t', those two characters will be replaced
         by the content-type field, including the  subtype,  if  any.
         (That    is,    if    the   content-type   was   "image/pbm;
         opt1=something-else",  then  "%t"  would  be   replaced   by
         "image/pbm".)   If the command field contains  "%{" followed
         by a parameter name and a closing "}", then all those  char-
         acters will be replaced by the value of the named parameter,
         if any, from the Content-type header.   Thus, in the  previ-
         ous example, "%{opt1}" will be replaced by "something-else".
         Finally, if the command contains "",  those  two  characters
         will be replaced by a single % ch
    
    
    
         aracter.  (In fact, the backslash can be used to  quote  any
         character, including itself.)
    
         If no "%s" appears in the command  field,  then  instead  of
         placing  the message body in a temporary file, metamail will
         pass the body to the command on the standard input.  This is
         helpful  in  saving  /tmp file space, but can be problematic
         for window-oriented applications under some  window  systems
         such as MGR.
    
         Two special codes can appear  in  the  viewing  command  for
         objects of type multipart (any subtype).  These are "%n" and
         "%F".  %n will be replaced by the number of parts within the
         multipart  object.  %F will be replaced by a series of argu-
         ments, two for each part, giving first the content-type  and
         then  the  name of the temporary file where the decoded part
         has been stored.  In addition, for each file created by  %F,
         a  second  file  is  created, with the same name followed by
         "H", which contains the header  information  for  that  body
         part.   This  will not be needed by most multipart handlers,
         but it is there if you ever need it.
    
         The "notes=xxx" field is an  uninterpreted  string  that  is
         used  to  specify  the name of the person who installed this
         entry in the mailcap file.  (The "xxx" may  be  replaced  by
         any text string.)
    
         The "test=xxx" field is a command that is executed to deter-
         mine whether or not the mailcap line actually applies.  That
         is, if the content-type field matches  the  content-type  on
         the  message,  but a "test=" field is present, then the test
         must succeed  before  the  mailcap  line  is  considered  to
         "match"  the  message  being viewed.  The command may be any
         UNIX command, using the same syntax and the  same  %-escapes
         as  for  the viewing command, as described above.  A command
         is considered to succeed  if  it  exits  with  a  zero  exit
         status, and to fail otherwise.
    
         The "print=xxx" field is a command that is executed to print
         the data instead of display it interactively.  This behavior
         is usually a consequence of invoking metamail with the  "-h"
         switch.
    
         The "textualnewlines"  field  can  be  used  in  the  rather
         obscure  case  where  metamail's  default rules for treating
         newlines in  base64-encoded  data  are  unsatisfactory.   By
         default,  metamail  will translate CRLF to the local newline
         character in decoded base64 output if  the  content-type  is
         "text" (any subtype), but will not do so otherwise.  A mail-
         cap entry with a field  of  "textualnewlines=1"  will  force
         such translation for the specified content-type, while "tex-
         tualnewlines=0" will guarantee that the translation does not
         take place even for textual content-types.
    
         The "compose" field may be used to specify  a  program  that
         can  be used to compose a new body or body part in the given
         format.  Its intended  use  is  to  support  mail  composing
         agents  that  support  the  composition of multiple types of
         mail using external composing  agents.  As  with  the  view-
         command,  the compose command will be executed after replac-
         ing certain escape sequences starting with "%".  In particu-
         lar,  %s  should  be replaced by the name of a file to which
         the composed data is to be written by the specified  compos-
         ing  program,  thus  allowing  th3e  calling  program  (e.g.
         metamail) to tell the called program where to store the com-
         posed  data.   If %s does not appear, then the composed data
         will be assumed to be written by the composing  programs  to
         standard  output.    The result of the composing program may
         be data that is NOT yet suitable for mail transport --  that
         is, a Content-Transfer-Encoding may still need to be applied
         to the data.
    
         The "composetyped" field is similar to the "compose"  field,
         but  is  to  be  used  when  the  composing program needs to
         specify the Content-type header field to be applied  to  the
         composed  data.  The "compose" field is simpler, and is pre-
         ferred for use with  existing  (non-mail-oriented)  programs
         for  composing  data  in a given format.  The "composetyped"
         field is necessary when the  Content-type  information  must
         include  auxilliary  parameters, and the composition program
         must then know enough about mail formats to  produce  output
         that  includes  the  mail type information, and to apply any
         necessary Content-Transfer-Encoding.    Conceptually,  "com-
         pose"  specifies a program that simply outputs the specified
         type of data in its raw form, while "composetyped" specifies
         a  program  that outputs the data as a MIME object, with all
         necessary Content-* headers already in place.
    
    
         needsterminal
                 If this flag is given, the named  interpreter  needs
                 to  interact  with  the user on a terminal.  In some
                 environments (e.g.  a  window-oriented  mail  reader
                 under  X11)  this will require the creation of a new
                 terminal   emulation   window,   while    in    most
                 environments  it  will  not.   If  the mailcap entry
                 specifies "needsterminal" and metamail is  not  run-
                 ning  on a terminal (as determined by isatty(3), the
                 -x option, and the MM_NOTTTY  environment  variable)
                 then  metamail  will try to run the command in a new
                 terminal  emulation  window.   Currently,   metamail
                 knows  how to create new windows under the X11, Sun-
                 Tools, and WM window systems.
    
         copiousoutput
                 This flag should be given whenever  the  interpreter
                 is  capable  of  producing  more than a few lines of
                 output on stdout, and does no interaction  with  the
                 user.  If the mailcap entry specifies copiousoutput,
                 and pagination has been requested via the "-p"  com-
                 mand,  then the output of the command being executed
                 will be piped through a pagination  program  ("more"
                 by  default,  but  this  can  be overridden with the
                 METAMAIL_PAGER environment variable).
    
    BUILT-IN CONTENT-TYPE SUPPORT
         The metamail program has built-in  support  for  a  few  key
         content-types.   In  particular,  it supports the text type,
         the  multipart  and  multipart/alternative  type,  and   the
         message/rfc822  types.   This support is incomplete for many
         subtypes -- for example, it only supports US-ASCII  text  in
         general.  This kind of built-in support can be OVERRIDDEN by
         an entry in any mailcap file  on  the  user's  search  path.
         Metamail  also  has  rudimentary  built-in support for types
         that are totally unrecognized -- i.e. for which  no  mailcap
         entry  or  built-in  handler  exists.  For such unrecognized
         types, metamail will write a file with a "clean" copy of the
         data  --  i.e.  a  copy  in which all mail headers have been
         removed, and in which any 7-bit transport encoding has  been
         decoded.
    
    FILES
         $HOME/.mailcap:/etc/mailcap:/usr/etc/mailcap:/usr/local/etc/mailcap
         -- default path for mailcap files.
    
    SEE ALSO
         metamail(1)
    
    COPYRIGHT
         Copyright  (c)  1991  Bell  Communications  Research,   Inc.
         (Bellcore)
    
         Permission  to  use,  copy,  modify,  and  distribute   this
         material  for any purpose and without fee is hereby granted,
         provided that the above copyright notice and this permission
         notice  appear  in all copies, and that the name of Bellcore
         not be used in advertising or publicity pertaining  to  this
         material  without  the specific, prior written permission of
         an authorized representative of Bellcore.  BELLCORE MAKES NO
         REPRESENTATIONS  ABOUT  THE  ACCURACY OR SUITABILITY OF THIS
         MATERIAL FOR ANY PURPOSE.  IT IS PROVIDED "AS  IS",  WITHOUT
         ANY EXPRESS OR IMPLIED WARRANTIES.
    
    AUTHOR
         Nathaniel S. Borenstein
    
    
    
    


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