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127 lines
4.7 KiB
Plaintext
127 lines
4.7 KiB
Plaintext
Managing External Viewers with Mailcap
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--------------------------------------
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This document describes the support for Mailcap (RFC 1524) in ELinks. It does
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not describe the mailcap format. There are plenty of documents on the Web that
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does this. Google and thou wilt find. ;)
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A Short Intro to Mailcap
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Mailcap is a file format defined in RFC 1524. Its purpose is to inform
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multiple mail reading user agent (MUA) programs about the locally-installed
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facilities for handling mail in various formats. It is designed to work with
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the Multipurpose Internet Mail Extensions, known as MIME.
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ELinks allows MIME handlers to be defined using its own configuration system,
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so why support mailcap? It can be seen as an alternative or simply as a
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supplement for setting up MIME handlers in ELinks. Mailcap files are present
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on most UNIX systems--usually in /etc/mailcap--so this makes it possible for
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ELinks to know how to handle a great variety of file formats with little
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configuration. To be able to use mailcap, it has to be compiled into ELinks.
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This is the default. If you don't need mailcap support, just configure ELinks
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with the flag: \--disable-mailcap.
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Parameters to Mailcap Entries
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The code has been ported from Mutt and thereby inherits some of its various
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features and limitation.
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The following parameters are supported:
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`---------------`-------------------------------------------------------------
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Parameter Description
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------------------------------------------------------------------------------
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%s The filename that contains the data.
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%f The content type, like 'text/plain'.
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------------------------------------------------------------------------------
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The following parameters are not supported, since they do not really make much
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sense for a non-MUA program:
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`---------------`-------------------------------------------------------------
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Parameter Description
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------------------------------------------------------------------------------
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%n The integer number of sub-parts in the multipart
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%F The "content-type filename" repeated for each sub-part
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%{ parameter} The "parameter" value from the content-type field
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------------------------------------------------------------------------------
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Reading of Mailcap Files
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~~~~~~~~~~~~~~~~~~~~~~~~
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Mailcap files will be read when starting ELinks. The mailcap files to use will
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be found from the mailcap path, a colon separated list of files similar to the
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$PATH environment variable. The mailcap path will be determined in the
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following way:
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- From the value of the mime.mailcap.path option in elinks.conf; for example:
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set mime.mailcap.path = "~/.mailcap:/usr/local/etc/mailcap"
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- From MAILCAP environment variable.
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- If non of the above is defined, the mailcap path defaults to
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`~/.mailcap:/etc/mailcap`.
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Fields
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~~~~~~
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Since mailcap handling is primarily for displaying of resources, all fields
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like edit, print, compose etc. are ignored.
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Note: Test commands are supported, but unfortunately, it's not possible to
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provide the file when running the test. So any test that requires a file will
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be considered failed and the handler will not be used.
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Unfortunately, there are no 'native' support for the copiousoutput field. The
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field basically mean 'needs pager'. So it is handled by appending a pipe and a
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pager program to the command. The pager program will be read from the `PAGER`
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environment variable. If this fails, test are made for common pager programs
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(`/usr/bin/pager`, `/usr/bin/less` and `/usr/bin/more` in that order). So if you
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define png2ascii as your handler for image/png and specify copiousoutput then
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the executed command will be "`png2ascii |/usr/bin/less`" if less is your pager
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or present on your system.
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Mailcap Configuration
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~~~~~~~~~~~~~~~~~~~~~
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Apart from the mime.mailcap.path option, you can configure if mailcap support
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should be disabled. The default being that it is enabled. To disable it just
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put:
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set mime.mailcap.enable = 0
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in elinks.conf.
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It is also possible to control whether ELinks should ask you before opening a
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file. The option is a boolean and can be set like this:
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set mime.mailcap.ask = 1
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if you would like to be asked before opening a file.
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Some Sample Mailcap Entries
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Below are examples of how to specify external viewers:
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-------------------------------------------------------------------------------
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# Use xv if X is running
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image/*; xv %s ; test=test -n "$DISPLAY";
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text/x-csrc; view %s; needsterminal
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# Various multimedia files
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audio/mpeg; xmms '%s'; test=test -n "$DISPLAY";
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application/pdf; xpdf '%s'; test=test -n "$DISPLAY";
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application/postscript; ps2ascii %s ; copiousoutput
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-------------------------------------------------------------------------------
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