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<title> ELinks Mailcap support </title>
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<h1> ELinks Mailcap support </h1>
<p>
This document describes the support for mailcap (rfc1524) in ELinks.
It does not describe the mailcap format. There are plenty of documents
on the web that does this. Google and thou shall find. ;)
</p>
<p>Index:<br />
<a href="#intro"> 1. A short intro to mailcap</a><br />
<a href="#parameters"> 2. Parameters</a><br />
<a href="#reading"> 3. Reading of mailcap files</a><br />
<a href="#fields"> 4. Fields</a><br />
<a href="#config"> 5. Configuration</a><br />
<a href="#sample"> 6. Some sample mailcap entries</a><br />
</p>
<hr />
<h2 id="intro">1. A short intro to mailcap</h2>
<p>
Mailcap is a file format defined in rfc 1524. It is purpose is to
inform multiple mail reading user agent (MUA) programs about the
locally-installed facilities for handling mail in various formats.
It is designed to work with the Multipurpose Internet Mail Extensions,
known as MIME.
</p>
<p>
ELinks supports <a href="mime.html">MIME</a> quite well already
so why support mailcap ? It can be seen as an alternative or simply as
a supplement for setting up mime handler. Mailcap files are present at
most UNIX systems (/etc/mailcap) so this makes it possible for ELinks
to know how to handle a great variety of file formats with little
configuration.
To be able to use mailcap it has to be compiled into ELinks. This
is the default. If you don't need mailcap support just configure
ELinks with the flag: <b>--disable-mailcap</b>.
</p>
<hr />
<h2 id="parameters">2. Parameters</h2>
<p>
The code has been ported from mutt and thereby inherits some of it's various
features and limitation.
</p>
<p>
The following parameters are not supported. Since they do not make
much sense for non-MUA:</p>
<dl>
<dt><b>%n</b></dt>
<dd> is the integer number of sub-parts in the multipart</dd>
<dt><b>%F</b></dt>
<dd>is "content-type filename" repeated for each sub-part</dd>
<dt><b>%{parameter}</b></dt>
<dd>is replaced by the parameter value from the content-type field</dd>
</dl>
<p> The following parameters are supported: </p>
<dl>
<dt><b>%s</b></dt>
<dd>is the filename that contains the data.</dd>
<dt><b>%f</b></dt>
<dd>is the content type, like text/plain</dd>
</dl>
<hr />
<h2 id="reading">3. Reading of mailcap files</h2>
<p>
Mailcap files will be read when starting ELinks. The mailcap files
to use will be found from the a mailcap path a colon separated list
of files similar to $PATH environment variable. The mailcap path
will be determined in the following way:
</p>
<ul>
<li>From the value of the <i>protocol.mailcap.path</i> option in
<b>elinks.conf</b> For example:
<pre>
<b>set</b> <i>protocol.mailcap.path</i> = <b>"~/.mailcap:/usr/local/etc/mailcap"</b></pre>
</li>
<li>From <b>MAILCAP</b> environment variable</li>
<li>If non of the above is defined the mailcap path defaults to
<b>"~/.mailcap:/etc/mailcap"</b></li>
</ul>
<hr />
<h2 id="fields">4. Fields</h2>
<p>
Since mailcap handling is primarily for displaying of resources all
fields like <b>edit</b>, <b>print</b>, <b>compose</b> etc. is ignored.
</p>
<p>
<b>Note:</b>
Test commands are supported but unfortunately it's not possible to
provide the file when running the test. So any test that requires a
file will be considered failed and the handler will not be used.
</p>
<p>
Unfortunately there are no 'native' support for the <b>copiousoutput</b>
field. The field basicly mean 'needs pager'. So it is handled by appending
a pipe and a pager program to the command. The pager program will be
read from the <b>PAGER</b> environment variable. If this fails test are made
for common pager programs (<b>/usr/bin/pager</b>, <b>/usr/bin/less</b> and
<b>/usr/bin/more</b> in that order). So if you define <b>png2ascii</b>
as your handler for <i>image/png</i> and specify copiousoutput then the
executed command will be <b>png2ascii |/usr/bin/less</b> if less is
your pager or present on your system.
</p>
<hr />
<h2 id="config">5. Mailcap configuration</h2>
<p>
Apart from the <i>protocol.mailcap.path</i> option you can configure
if mailcap support should be disabled. The default being that it is
enabled. To disable it just put:
</p>
<pre>
<b>set</b> <i>protocol.mailcap.enable</i> = <b>0</b></pre>
<p>
in <b>elinks.conf</b>.
</p>
<p>
It is also possible to control wether ELinks should ask you before
opening a file. The option is a boolian and can be set like this:
</p>
<pre>
<b>set</b> <i>protocol.mailcap.ask</i> = <b>1</b></pre>
<p>
if you would like to be asked before opening a file.
</p>
<hr />
<h2 id="sample">6. Some sample mailcap entries</h2>
<pre>
<b># Use xv if X is running</b>
<i>image/*</i>; xv %s ; test=test -n "$DISPLAY";
<b># Convert images to text using the netpbm tools</b>
<i>image/*</i>; (anytopnm %s | pnmscale -xysize 200 150 | \
pnminvert | ppmtopgm | pgmtopbm | \
pbmtoascii -1x2 ) 2>&1 ; copiousoutput
<b># Various multimedia files</b>
<i>audio/mpeg</i>; xmms '%s'; test=test -n "$DISPLAY";
<i>application/pdf</i>; xpdf '%s'; test=test -n "$DISPLAY";
<i>application/postscript</i>; ps2ascii %s ; copiousoutput
</pre>
<p>
<tt>$Id: mailcap.html,v 1.4 2003/10/16 13:12:02 zas Exp $</tt>
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