texinfo/programs/mimeview.texi

@c This is part of the GNU Mailutils manual.
@c Copyright (C) 1999--2021 Free Software Foundation, Inc.
@c See file mailutils.texi for copying conditions.
@comment *******************************************************************
@pindex mimeview

  For each file given in its command line, @command{mimeview} attempts
to autodetect its type and invoke an appropriate file viewer.

  To detect the file type, @command{mimeview} uses @file{mime.types}
file.  This file is a part of Common UNIX Printing System,
@ref{mime.types,,,mime.types(5), mime.types man page}.  By default
@command{mimeview} searches for @file{mime.types} in
@file{$prefix/etc/cups/}@footnote{The exact location is determined at
configuration time by setting environment variable
@env{DEFAULT_CUPS_CONFDIR}.  On most sites running

@example
./configure DEFAULT_CUPS_CONFDIR=/etc/cups
@end example

@noindent
should be recommended.}, however its exact location can be specified
at runtime as well (see @option{--mimetypes} below).

  Once file MIME type is successfully determined, @command{mimeview}
consults @file{mailcap} files in order to determine how to display
the file.  It does so essentially in the same manner as
@command{metamail} utility, i.e., it scans all files specified
in @code{METAMAIL} environment variable until it finds an entry
describing the desired file format or until the list of files is
exhausted.  If @code{METAMAIL} variable is not set, @command{mimeview}
uses the following default path instead:

@example
$HOME/.mailcap:/usr/local/etc/mailcap:\
 /usr/etc/mailcap:/etc/mailcap:\
 /etc/mail/mailcap:/usr/public/lib/mailcap
@end example

@menu
* Mimeview Invocation::
* Mimeview Config::
@end menu

@node Mimeview Invocation
@subsection Mimeview Invocation

  The following table summarizes options specific for @command{mimeview}:

@table @option
@item -a[@var{type-list}]
@itemx --no-ask[=@var{type-list}]
By default @command{mimeview} asks for confirmation before running
interpreter to view a message.  If this option is used without
argument, it disables the default behavior for all message
types.  Otherwise, if argument @var{type-list} is given, it specifies
a comma-separated list of MIME types for which no questions should be
asked.  Elements of this list may include shell-style globbing
patterns, e.g. setting

@example
--no-ask='text/*,image/jpeg'
@end example

@noindent
will disable prompting before displaying any textual files, no
matter what their subtype is, and before displaying files with
type @samp{image/jpeg}.

  Notice, that when the long form is used, its argument
must be separated from the option by a single equal sign, as shown
in the example above.  When the short form (@option{-a}) is used, its argument
must follow the option immediately, without any intervening whitespace,
e.g.  @option{-a'text/*'}).

@item -d[@var{flags}]
@itemx --debug[=@var{flags}]
Enables debugging output.  @var{Flags} is a sequence of characters
specifying the desired debugging level.  Following characters are
meaningful in @var{flags}:

@table @asis
@item g
Enables debugging of @file{mime.types} parser

@item l
Enables debugging of @file{mime.types} lexical analyzer (warning:
produces @emph{very} copious output)

@item 0
Prints basic information about actions to be executed and reports
about exit status of executed commands.

@item 1
Additionally displays each file name along with its MIME type

@item 2
Additionally traces the process of looking up the matching entry
in @code{mailcap} files.

@item 3
Additionally, enables debugging of @file{mime.types} parser (@samp{g}).

@item 4
Additionally, enables debugging of @file{mime.types} lexer (@samp{l}).

@item digits from 5 to 9
The same as 4, currently.
@end table

If @var{flags} are not given, the default @samp{2} is assumed.

@item --metamail[=@var{file}]
Run @command{metamail} to display files, instead of using the internal
mechanisms.  If @var{file} is specified, it is taken as
@command{metamail} command line.

@item -h
@itemx --no-interactive
@itemx --print
This options tells @command{mimeview} that it should run in
non-interactive mode.  In this mode prompting is disabled, and
the normal mailcap @code{command} field is not executed.  Instead
@command{mimeview} will execute the command specified in
the @code{print} field.  If there is nothing in the print field,
the mailcap entry is ignored and the search continues for a matching
mailcap entry that does have a @code{print} field.

Notice, that unlike in @command{metamail -h}, this option does
not force @command{mimeview} to send the output to the printer
daemon.

When used with @option{--metamail} option, this option passes
@option{-h} flag to the invocation of @command{metamail}.

By default @command{mimeview} behaves as if given
@option{--no-interactive} option whenever its standard input is not
a @asis{tty} device.

@item -i
@itemx --identify
Identifies and prints the MIME type for each input file.

@item -n
@itemx --dry-run
Do not do anything, just print what would be done.  Implies
@option{--debug=1}, unless the debugging level is set up explicitly.

@item -f @var{file}
@itemx --mimetypes @var{file}
Use @var{file} as @file{mime.types} file.  If @var{file} is a
directory, use @file{@var{file}/mime.types}

@item -t
@itemx --lint
Check syntax of the @file{mime.types} file and exit.  Command line
arguments are ignored.
@end table

@node Mimeview Config
@subsection Mimeview Config

The following configuration statements affect the behavior of
@command{mimeview}:

@multitable @columnfractions 0.3 0.6
@headitem Statement @tab Reference
@item debug @tab @xref{Debug Statement}.
@end multitable

@deffn {Mimeview Config} mimetypes @var{file}
Read @var{file} instead of the default @file{mime.types}.
@end deffn

@deffn {Mimeview Config} metamail @var{program}
Use @var{program} to display files.
@end deffn