R3R man page

 r3r [URL]
 r3r-conv -i input_file -t output_type [-o output_file]
 r3r_opml 0|1 [infile [outfile]]

  r3r takes an HTTP URL or a local file and reads it. The subscriptions file can be used to load certain feeds on every startup.

R3R currently supports the formats RSS (0.9—2.0), RSS 3.0, Atom, and ESF. It will extract the format from the HTTP content type or the file extension. Content-type guessing can be enabled, which will analyze HTTP URLs for hopefully better results.

Content types:
 application/rdf+xml, application/rss+xml: RSS (0.9—2.0)
 application/atom+xml: Atom
 text/x-rss, text/plain: RSS 3.0
 esf/text: ESF

File extensions:
 .rss, .rdf: RSS (0.9—2.0)
 .r3, .rss3: RSS 3.0
 .atom: Atom
 .esf: ESF

 r3r-conv can be used to convert between file formats.

 config/r3r/r3r.ini
  Settings file.
 data/r3r/clav
  Key bindings (TUI).
 data/r3r/history
  History of visited URLs.
 data/r3r/subscriptions.txt
  URLs to which you've subscribed.
  r3r_opml can be used to import an OPML file from an existing feed reader.

Filters can be created in the data directory. They have the name <field>.filter, where <field> can be title, subject, author, etc. The file will contain text entries or regular expressions to block, one on each line. Example:
foo
/b[aeiou]r/i
/Baz/

The TUI is the most mature of the user interfaces (the one I use most often). It displays a list of items in the left pane and important data about it in the right pane. You can scroll through the items via customary keys. Press h within the program for more help about the keys.

The GUI is nothing but a technology demonstration of using the Pascal shared library from a C++ program (it should be usable also from other programming languages), but it's usable. It displays a list of items in a list view. Selecting an item, will display its contents in a web widget. Subscriptions can be managed from the settings dialog.

The HTML UI is also usable. When called, it writes an HTML web page to standard output. That output can be directed to a file. On a web server, this can easily be invoked for remote access of your favorite feeds.

Please look in subdirectories in ./doc of the source distribution for pertinent information about building, development, writing your own UI, etc.