Newsboat contains support for Snownews extensions. The
RSS feed readers Snownews and Liferea share a common way of extending the
readers with custom scripts. Two mechanisms, namely "execurl" and "filter" type
scripts, are available and supported by Newsboat.

An "execurl" script can be any program that gets executed and whose output is
interpreted as RSS feed, while "filter" scripts are fed with the content of a
configured URL and whose output is interpreted as RSS feed.

The configuration is simple and straight-forward. Just add to your _urls_ file
configuration lines like the following ones:

	exec:~/bin/execurl-script
	filter:~/bin/filter-script:https://some.test/url

The first line shows how to add an execurl script to your configuration: start
the line with `exec:` and then immediately append the path of the script that
shall be executed.  If this script requires additional parameters, simply use
quotes (see <<_using_double_quotes>> for details):

	"exec:~/bin/execurl-script param1 param2"

The second line shows how to add a filter script to your configuration: start
the line with `filter:`, then immediately append the path of the script, then
append a colon (`:`), and then append the URL of the file that shall be fed to
the script. Again, if the script requires any parameters,
<<_using_double_quotes,simply quote the whole thing>>:

	"filter:~/bin/filter-script param1 param2:https://url/foobar"

In both cases, the tagging feature as described above is still available:

	exec:~/bin/execurl-script tag1 tag2 "quoted tag"
	filter:~/bin/filter-script:https://some.test/url tag3 tag4 tag5

If you need to write your own extension, see
https://web.archive.org/web/20090724045314/http://kiza.kcore.de/software/snownews/snowscripts/writing[this
short guide] for an introduction. A collection of existing
https://github.com/msharov/snownews/tree/de3bd8b28191c4d4bc1be18275786613bcbc0c94/docs/untested[scripts]
and
https://github.com/msharov/snownews/tree/9fb45e4cdf1cf9dea55b9af66c13a4c238809851/docs/filters[filters]
might help, too.

Newsboat comes with an example exec script which shows one way to generate an
RSS channel. It also includes a way to see which exact arguments are passed to
the script by Newsboat. This example can be found in the _doc/examples_
subdirectory.
