CHA-MAILCAP(5)

Mailcap
By default, Chawan’s buffers only handle HTML and plain text. The mailcap file can be used to view other file formats using external commands, or to convert them to HTML/plain text before displaying them in Chawan.

Note that Chawan’s default mime.types file only recognizes a few file extensions, which may result in your entries not being executed if your system lacks an /etc/mime.types file. Please consult cha-mime.types(5) for details.

For an exact description of the mailcap format, see RFC 1524 (https://www.rfc-editor.org/rfc/rfc1524) .

  Search path
The search path for mailcap files is set by the configuration variable external.mailcap. This matches the recommended path in the RFC:

        $HOME/.mailcap:/etc/mailcap:/usr/local/etc/mailcap

By default, mailcap entries are only executed if the user types r (run) after the prompt. Other options are to view the file with t (text), or to save the file with s.

If a capital letter is typed (e.g. shift + R), then a corresponding entry is appended to external.auto-mailcap (default: ~/.chawan/mailcap, or ~/.config/chawan/mailcap with XDG basedirs). (T)ext and (S)ave may also be used to append entries corresponding to the other display options.

Entries in auto-mailcap are automatically executed, so it is recommended to add your Chawan-specific entries there (or just set it to your personal mailcap file).

  Format
Chawan adheres to the format described in RFC 1524, with a few extensions.

text/html and text/plain entries are ignored.

  Templating
The command part of entries may include template strings which are substituted by the browser at execution.

Templates do not have to be quoted; Chawan quotes them automatically. (This works with $(command substitutions) as well.) However, other software may misbehave on such templates, so it may be better to assign them to a variable first, e.g.

        text/x-example; s=%s cat "$s"; copiousoutput

Following templates are supported:

•   %s expands to the path. Specifying %s forces download of the external resource before the entry is executed. If %s is not specified, the resource is instead piped to standard input. (In this case, needsterminal does not apply.)

•   %t expands to the content type. Named content type fields can also be specified with the syntax %{charset}. For example, in

            text/html; charset=utf-8

    %t would expand to the above string, while %{charset} would expand to “utf-8”.

•   Non-standard templates for the resource’s original URL: %u (from Netscape) expands to the original URL of the resource, %h (from w3mmee) expands to the hostname without the port, %H expands to the hostname including the port, and %? (from w3mmee) expands to the query string including the question mark.

    (w3mmee did not actually include the question mark in %?. However, that design could not express the difference between the empty query string and the null query string, so it has been changed in Chawan.)

  Fields
Following fields are recognized.

•   When the test named field is specified, the mailcap entry is only used if the test command returns 0. For example, you can restrict entries that require X11 as follows:

            image; feh -; test=test -n "$DISPLAY"

    Warning: %s does not work with test. test named fields with a %s template are skipped, and no data is piped into test commands.

•   copiousoutput makes Chawan redirect the output of the external command’s output into a new buffer. If either x-htmloutput or x-ansioutput is defined too, then copiousoutput is ignored.

•   needsterminal hands over control of the terminal to the command while it is running. It does nothing if one of copiousoutput, x-ansioutput, x-saveoutput or x-htmloutput is specified.

•   nametemplate provides a specific template for the temporary file created when %s is specified. See the RFC for details.

•   x-htmloutput (from w3m) behaves the same as copiousoutput, but makes Chawan interpret the command’s output as HTML.

•   x-ansioutput pipes the output through the “text/x-ansi” content type handler, so that ANSI colors, formatting, etc. are displayed correctly.

•   x-saveoutput prompts the user to save the entry’s output in a file.

•   x-needsstyle forces CSS to be processed for the specific type, even if styling is disabled in the config. Only useful when combined with x-htmloutput. (Also see the -cha-content-type media query in cha-css(7).)

•   x-needsimage forces images to be displayed in x-htmloutput, even if images are disabled.

•   x-type (from w3mmee) specifies a MIME type substitution. The command part is interpreted as a MIME type (without template expansion) which is used instead of the original type. Such entries are only respected in external.auto-mailcap.

    Entries with x-type also match text/plain and text/html documents (which are normally excluded from mailcap). However, x-type does not apply if the content type was forced (e.g. using the -T flag).

    (Note: x-type is experimental. Future changes to its semantics are to be expected.)

•   x-match (from w3mmee) restricts the entry’s URL to the specified regex. x-nc-match is the same, but it is case-insensitive. For example, x-match=https?://example\.org/.* restricts the entry to example.org (note the backslash.)

    When one of these fields is present together with test, the result is ANDed together.

•   x-netpath (from w3mmee) restricts the entry to URIs that match the net_path production of RFC 2396. In other words, the URI must have an authority (hostname etc.), so e.g. example://blah/path is matched, while example:/path isn’t.

    For schemes other than file, two slashes after the colon signify a net_path. file:///path is a special case: it looks like a net_path, but it isn’t one. (This is inherited from the WHATWG URL standard.)

  Examples
To automatically execute these entries, place them in ~/.chawan/mailcap (or ~/.config/chawan/mailcap if you use XDG basedirs). Alternatively, if you already have a mailcap file to share with other programs, you can set external.auto-mailcap to ~/.mailcap.

        # Note: these examples require an entry in mime.types that sets e.g. md as
        # the markdown content type.

        # Handle markdown files using pandoc.
        text/markdown; pandoc - -f markdown -t html -o -; x-htmloutput

        # Show syntax highlighting for JavaScript source files using bat.
        text/javascript; bat -f -l es6 --file-name %u -; x-ansioutput

        # Play music using mpv, and hand over control of the terminal until mpv exits.
        audio/*; mpv -; needsterminal

        # Play videos using mpv in the background, redirecting its standard output
        # and standard error to /dev/null.
        video/*; mpv -

        # Open docx files using LibreOffice Writer.
        application/vnd.openxmlformats-officedocument.wordprocessingml.document; lowriter %s

        # Display manpages using pandoc. (Make sure the mime type matches the one
        # set in your mime.types file for extensions .1, .2, .3, ...)
        application/x-troff-man; pandoc - -f man -t html -o -; x-htmloutput

        # epub -> HTML using pandoc. (Again, don't forget to adjust mime.types.)
        # We set http_proxy to keep it from downloading whatever through http/s.
        application/epub+zip; http_proxy=localhost:0 pandoc - -f epub \
        --embed-resources --standalone; x-htmloutput

        # Hex viewer.  Usage: alias chadump='cha -Ttext/x-hexdump'
        # (Uses GNU-specific flags, adjust as needed on other systems.)
        text/x-hexdump; od -w12 -A x -t x1z -v; copiousoutput

        # Following entry will be ignored, as text/html is supported natively by Chawan.
        text/html; cha -dT text/html -I %{charset}; copiousoutput

  See also
cha(1)