newslinkrss 0.12.0

Generate RSS feeds for sites that do not have them

About

newslinkrss generates RSS feeds for websites that do not provide their own. It works by loading URLs with lists of articles, looking for links matching regular expressions, and optionally visiting them to get more information and even processing these target pages with XPath and CSS Selectors if necessary. It is basically a purpose-specific crawler or scraper.

The results are printed as a RSS feed to stdout or optionally to a file. The simplest way to use it is just configure your local feed reader, like Liferea or Newsboat, to use a "command" source and pass the correct command line arguments to generate a suitable feed -- this allows you to centralize the configuration in the reader itself and let it handle update times, etc.

Run newslinkrss --help for the complete list of command line options.

Intended audience (and a rant)

This script is mostly intended to technically versed people using some kind of Unix operating system (e.g. Linux). I was planning to write a detailed documentation but I just gave up. There is no much hope of making it friendly to casual users when every use case requires complex command lines, abuse of regular expressions, strftime strings, XPath, CSS Selectors, etc.

The Rant

Everything would be just easier if websites simply provided clean and complete RSS or Atom feeds, but these sites are becoming rarer every day. Most sites assume we want to follow them through social media (or that we use social media!) and expect us to give away our privacy and submit ourselves to tracking and personal data collection in exchange for timelines algorithmically optimized to improve "engagement" with advertisers.

I'm still resisting and wrote lots of feed scrapers/filters in the last 18 or so years; newslinkrss is one that replaced several of these ad-hoc filters by centralizing some very common pieces of code and it is polished enough to be published.

Installation

Installing from PyPI

This is the simplest installation method and will deliver the latest stable version of the program. To install in your $HOME directory, just type:

pip3 install newslinkrss

This assumes pip3 is installed and configured (which usually happens by default in Linux distributions intended for general use).

Installing from the Git repository

This installation process is recommended for developers and people wanting the newest version. For that, just clone the Git repository and install or update the program with:

pip3 install -U .

You may want to do this in a virtual environment so it won't interfere with other user-level or system-wide components and make experimentation with development versions easier. In this case, just do:

python3 -m venv my-venv
. my-venv/bin/activate
pip install -U .

newslinkrss depends on a few libraries, this will ensure all them are also installed correctly.

Installing from the Snap

newslinkrss is also available as a Snap. This makes easy to always have the latest version, updated automatically, and do not requires creating Python virtual environments or touching user or system level Python modules. To install in any Snap-enabled distribution, run:

sudo snap install newslinkrss

This will install and follow to the latest stable version; if you want to always have the latest development version, freshly built from the Git master branch, install it from the "edge" channel with:

sudo snap install newslinkrss --edge

Usage examples

newslinkrss is lacking a lot of documentation, but the following examples can show a bit of what it can and can not do. To make understanding easier, examples uses mostly the long, verbose, form of some options even when abbreviations are available. A complete list of options, abbreviations, default values, etc. can be read by typing newslinkrss --help.

Simplest case

The simplest use case is just load a website, select all links matching a pattern and expose a feed using the text of that link as description and setting the publish date to the date and time that the command was run. For example, to generate a feed from site https://www.jaraguadosul.sc.gov.br/noticias.php , collecting all links with the substring /news/ in the URL, use:

newslinkrss -p '.+/news/.+' https://www.jaraguadosul.sc.gov.br/noticias.php

It won't generate a good feed (the limitation with the dates being the biggest issue) but we will go back to this example later. It is already more practical than checking this government website manually, however.

Following pages

To improve the situation exposed in the previous example, we may want to get information that it not is available from the URL or anchor text. Option --follow (shortcut -f) will make newslinkrss load the candidate target page and look for more data there. By default, it automatically captures the title of the page as the title of the feed entry, keeps the summary from anchor text, and loads author information and the page publishing and update dates and times from the page metadata (if this information is available in some common format, like Open Graph or Twitter cards.

Reuters killed its RSS feeds in mid 2020, so let's take them as an example and use newslinkrss to bring the feed back to life and right into our news readers. Our criteria will be:

• First we must find every link that appears as plain HTML on the front page: https://www.reuters.com/ There is an infinite scroll and more links are added periodically with JavaScript, but we can just ignore this and poll the page more frequently, giving enough chance to capture them;

• We want to be very selective with filtering so we only get the current news and do not waste time downloading things like section listings, utility pages, links for other domains, etc. By looking at the URLs of the news pages, we can notice that all of them follow a pattern similar to: https://www.reuters.com/world/europe/eu-proposes-create-solidarity-fund-ukraines-basic-needs-2022-03-18/ Notice they all are in domain "https://www.reuters.com/", have at least one section ("/world/europe/") that is followed by part of the title and the publish date. This format is really great, as it allows us to ignore anything that does not look like a news article on the spot. So, a good pattern will be 'https://www.reuters.com/.+/.+\d{4}-\d{2}-\d{2}.+';

• newslinkrss deduplicates URLs automatically, so we don't need to worry if we end up capturing the same link twice;

• Target pages have Open Graph meta tags, so by just following them we can get accurate publish dates and times with no extra effort. Better yet, as we know that all news pages that we want have them, we can also instruct newslinkrss to ignore any page without a valid date, preventing any non-news article, captured by accident, from appearing in our feed. This is done with option --require-dates;

• All page titles are something like "The actual headline | Reuters". This format is nice for a website but not so for feed items: the "| Reuters" part is not only redundant (the feed title already tells us about the source of the article) but also noisy, as it makes scanning through the headlines harder. newslinkrss has an option --title-regex for exactly this use case of cleaning up redundant text from titles. It accepts a regular expression with a single capture group; if the expression matches, the text from the group will be used as the title, otherwise the original text will be used (so we don't loose titles if something changes at the source, for example). For this case, a good choice would be --title-regex '(.+)\s+\|' .

• When following pages we must be very careful as we do not want to abuse the website or get stuck downloading gigabytes of data. newslinkrss has several options to prevent these problems, all with sensible default values, but we should check if they work for every use case. At first we must limit number of links to be followed with option --max-links (the default value is 50, so it is OK for this so we can just omit the option for now), then we may use option --max-page-length to only load the first 512 kB of data from the every followed link, and stop processing a page after after a few seconds with option --http-timeout (the default value is 2 s, so we can omit this option for now too);

• Cookies will be remembered among these requests, but they will only be kept in memory and forgotten once the program finishes (there is an option --no-cookies if this behavior becomes a problem for a particular source).

So, our syntax for this will be:

newslinkrss \
    --follow \
    -p 'https://www.reuters.com/.+/.+\d{4}-\d{2}-\d{2}.+' \
    --max-page-length 512 \
    --require-dates \
    --title-regex '(.+)\s+\|' \
    https://www.reuters.com/

Generating complete feeds

Complete feeds are the ones which include the full text of the article with it, instead of just a summary and a link. They are really nice as we can read everything in the news aggregator itself. A good item body should be mostly static and clean HTML (so no scripts, interactive content, aggressive formatting, etc.) leaving everything else to the aggregator to handle.

So let's extend the previous example from Reuters website: as we are already following and downloading the links, there is no much extra work to generate the full feed from it. Option --with-body will copy the entire contents of the "body" element from the page into the feed, just removing a few obviously unwanted tags (scripts, forms, etc.).

Including the entire body works for every case, but for this site we can filter a bit more and pick only actual text of the news article, ignoring unwanted noise like menus, sidebars, links to other news, etc. Running a quick "inspect element" in Firefox shows us that there is a single "article" element in the pages and that it has the text we want. newslinkrss allows using both XPath expressions and CSS Selectors to pick particular elements from the DOM and, for this case, we choose XPath by using option --body-xpath '//article' — sometimes CSS Selectors are easier and cleaner, if it appears that you are struggling too much with a particular XPath expression, try using a CSS Selector with --body-csss instead.

So, the updated syntax will be:

newslinkrss \
    --follow \
    -p 'https://www.reuters.com/.+/.+\d{4}-\d{2}-\d{2}.+' \
    --max-page-length 512 \
    --with-body \
    --body-xpath '//article' \
    --require-dates \
    --title-regex '(.+)\s+\|' \
    https://www.reuters.com/

And now we have our feed!

The body for this example is very simple but the selectors (both XPath and CSSS) are surprisingly powerful. They can return any number of elements in any order, so you can create a readable item body from whatever exists in the source page by carefully picking elements in the right order (XPath operator "|" and CSSS "," are your friends!).

Cleaning body elements (and handling bad CSS class names)

If we look at the bodies captured with the previous Reuters example, we will notice that (at least in July 2023 when this text is being written) there are still some unwanted elements that add too much noise to the output. Inside the article element, we also get:

• Social media share buttons: actually, not the buttons themselves because for elements are removed by default, but the ul and li elements that encapsulated them remain -- newslinkrss simple does not know which ones are useful and which ones are not, so it can not remove them automatically;

• Related articles and "Read next" sections: we want only the text of the current article in a clean and readable format.

Usually it is very easy to get rid of these using options --body-remove-xpath (shortcut -X) and --body-remove-csss (shortcut -C), but this particular site has a very non-semantic structure and uses automatically generated and unstable-looking class names like article-header__toolbar__3lT1M, article-body__toolbar__1_CO8, and article__read-next__Kjxdw. However, we can notice a pattern here: there are some stable prefixes and random suffixes that will possibly change faster than the "stable" part.

We can handle these with a bit more advanced object selections. For this case, let's use CSS Selectors as they are a bit shorter and more readable:

• First, we look for attribute substrings and remove the toolbars with a --body-remove-csss 'div[class*="article-header__toolbar__"], div[class*="article-body__toolbar__"]'. Notice that we are playing really loose here! The first rule does not mean "any div element marked with a class with a name starting with article-header__toolbar__", it actually means "any div element with a class attribute containing the substring article-header__toolbar__". In a site with shorter class names, we would probably face a lot of false positives! But extracting feeds is almost always a game of kludges, so let it be.

• Do the same hack for the related articles but, looking a bit closer we can notice that inside its main div we also have another tagged with class read-next-panel, which is a pretty readable and stable-looking name! So let's add an extra standard match for it as a fail-safe in the event the external div stops matching; it will still leave some garbage text, but will remove the most of the article list. The syntax is --body-remove-csss 'div[class*="article__read-next__"], div.read-next-panel'.

We could have combined these two rules in one, but leaving them separate makes debugging easier as the rules are printed with the log messages when running with --log debug, allowing us to see which ones are matching.

It is also important to notice that options --body-remove-* work over the DOM that was generated from --body-xpath or --body-csss. These options allows a lot of control over the way the elements are copied from the main document DOM, and the result can end up being very different once we start using some clever selections.

So, our updated command line is now:

newslinkrss \
    --follow \
    -p 'https://www.reuters.com/.+/.+\d{4}-\d{2}-\d{2}.+' \
    --max-page-length 512 \
    --with-body \
    --body-xpath '//article' \
    --body-remove-csss 'div[class*="article-header__toolbar__"], div[class*="article-body__toolbar__"]' \
    --body-remove-csss 'div[class*="article__read-next__"], div.read-next-panel' \
    --require-dates \
    --title-regex '(.+)\s+\|' \
    https://www.reuters.com/

... and it gives us a cleaner feed!

A single feed from multiple start URLs

It is possible to have several start URLs and make newslinkrss generate a single feed with content gathered from all of them, all other options remaining the same. Typically, this can be used to filter only the sections of interest from a site while keeping all articles in the same subscription in your newsreader.

Let's continue with our Reuters example, but imagine we only want articles from sections "World" and "Technology". We noticed before that the section names appears in the URL, so a first approach may be just hack the link pattern to require (world|technology) in it. However this solution may fail to grab, for example, some news articles that appears in the "technology" page but have a different section in their URLs (as they can be related to both) or skip articles that do not appear in the front page at all (as space there is limited).

This can be solved with this command:

newslinkrss \
    --follow \
    -p 'https://www.reuters.com/.+/.+\d{4}-\d{2}-\d{2}.+' \
    --max-page-length 512 \
    --with-body \
    --body-xpath '//article' \
    --body-remove-csss 'div[class*="article-header__toolbar__"], div[class*="article-body__toolbar__"]' \
    --body-remove-csss 'div[class*="article__read-next__"], div.read-next-panel' \
    --require-dates \
    --title-regex '(.+)\s+\|' \
    --title "Reuters (Technology and World only)" \
    https://www.reuters.com/technology/ https://www.reuters.com/world/

Notice that it is almost the same command line used in the previous example, except for the multiple URLs and option --title, which allow us to give an alternate title to the feed. This is welcome because newslinkrss picks the title from the first URL that has one, and it may be related to the first section only (alternatively, you can rename the feed in your newsreader if it has an option for it).

When using multiple start pages, a special attention is required to the parameter --max-links! If the limit is reached in a page, links loaded from later pages will be skipped.

This feature may be also used to capture more items from sites that split them in very short pages but does still have stable pagination URLs, like: https://news.example.org/page-1.html https://news.example.org/page-2.html https://news.example.org/page-3.html. If you are using newslinkrss in a shell script, you may avoid repeated URLs by using sequence expansions (in bash) or seq -f (in everything else).

Gathering information from limited metadata

Some sites do not provide standard (not even quasi-standard) metadata that newslinkrss can use automatically, so we must gather it from the pages with site-specific approaches, following links and stitching information from several elements together. Assume we want to generate a feed from https://revistaquestaodeciencia.com.br/ , which provides no much facilities for it. Looking into the site we find that:

• URLs for news articles have a date on them (in format YYYY/MM/DD), so it is possible to use this in the URL pattern (option -p) to limit which links the script will look for. Some are prefixed by a section stub and all are followed by a string generated from the title, so the regex must accept the date anywhere in it. Anything could be a filter here, but as all articles have a date on it we don't need to look anywhere else;

• There is no standard, not even de-facto standard, representation for the date an article was published, so the alternative is taking it from the URL too. This is done with options --date-from-url (which requires regular expression with a group capturing the substring that contains the date) --url-date-fmt (which defines the format of the date);

• Inconsistencies in the link formats prevent us from getting all articles titles from the links in the front page, so the alternative is to --follow every candidate link, downloading the target page and looking for the title there.

• As we are already following, there is no much extra effort to also generate a complete feed. The full text of the article is in an "article" element, so we can use --body-xpath "//article" here too.

• The target page has no author information in its metadata so newslinkrss will not be able to find their names automatically. However, it has a link to the list of articles from the same author in format <a href="/autor/author-name">Author Name</a> and we can use the prefix from attribute href to pick it with XPath (using option --author-from-xpath) or CSS Selectors (with --author-from-csss). The CSS approach is simpler for this particular case, so let's use an --author-from-csss 'a[href^="/autor/"]'. While not required for this site (name is the only child element of "a"), some sites may prefix the author name with a "by " or similar; For these cases, we could also use options --csss-author-regex and --xpath-author-regex to select only the name with a regular expression. Also notice that author is an optional element in both RSS and Atom, but it is nice to have it appearing in the correct fields in the news reader so we can use this information for filtering reading lists, for example.

The resulting command line is:

newslinkrss \
    -p 'https://revistaquestaodeciencia.com.br/.*\d{4}/\d{2}/\d{2}/.+' \
    --date-from-url '.*/(\d{4}/\d{2}/\d{2})/.*' \
    --url-date-fmt '%Y/%m/%d' \
    --follow \
    --with-body \
    --body-xpath "//article" \
    --author-from-csss 'a[href^="/autor/"]' \
    --max-page-length 512 \
    --http-timeout 4 \
    --title-regex '(.+)\s+\|' \
    'https://revistaquestaodeciencia.com.br/'

Using complex XPath expressions

Sometimes we need to fight really hard to get the date that a particular item was last updated. Taking GitHub issues as an example: while GH provides Atom feeds for releases and commits (but always to specific branches), there is no equivalent for issues and pull requests. Of course, there is an API for that but it requires authentication with a GitHub account, enables tracking, and requires writing a specific bridge to get the data as a feed. This makes the scraping approach easier even with the very convoluted example that follows.

The URLs for issues and PRs are pretty usable, we can already use them to limit how many issues will be shown, their status, filter by date, etc. Just look at the one used in the example.

However, we need to get the date of the last comment on the issue and set it as the publishing date of the item, otherwise the reader won't show us that it was updated. A solution is to follow every issue page while using a XPath expression to find the last occurrence of a "relative-time" tag that GitHub uses to mark the timestamp of a comment and parse the absolute date from attribute "datetime". This is done with options --date-from-xpath and --xpath-date-fmt.

The resulting command line is the following:

newslinkrss \
    --follow \
    --with-body \
    --http-timeout 5 \
    --max-links 30 \
    --max-page-length 1024 \
    -p '^https://github.com/.+/issues/\d+$' \
    --date-from-xpath '(//h3/a/relative-time)[last()]/@datetime' \
    --xpath-date-fmt '%Y-%m-%dT%H:%M:%SZ' \
    'https://github.com/lwindolf/liferea/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc'

Debugging XPath expressions is not a very easy task, the simplest way is just open the target page in Firefox, launch web developer tools and use the $x() helper function to get what the expression will return, for example: $x('(//h3/a/relative-time)[last()]/@datetime').

The first example, revisited

Now that we have a few extra tricks in our sleeves we can check back that very first example and fix some of its limitations:

• First, we need the correct publish dates; they are neither in the URL nor in the anchor text, so we need to --follow the pages and get the dates from there. The pages also have no metadata to do this easily, but they have a publish date intended for human readers in a slice of HTML like this: <small class="text-muted"><b>23/12/2022</b> - some unrelated text</small>, so it is pretty easy to get it with a CSS selector: --date-from-csss 'small.text-muted > b'. It will capture the "23/12/2022" from the text node of inner element "b", no need to filter through --csss-date-regex to remove unwanted text, but the date format is still ambiguous so we need to give an explicit format with option --csss-date-fmt '%d/%m/%Y';

• Let's be extra careful with the URL pattern and never capture (or follow!) links pointing to other domains. We can replace it with a more restricted -p 'https://www.jaraguadosul.sc.gov.br/news/.+';

• As we are already following the pages, let's also generate a full feed. The relevant part of the articles are inside a "div" element with attribute "id" set to "area_impressao" (that's Portuguese for "printing_area" and one may imagine it is being used to format the page for printing, however there is neither an alternate style sheet nor a @media selector for it ... anyway, at least it helps us to select the correct text). We can isolate this element with a XPath expression '//div[@id="area_impressao"]' but this is slightly more complex than the equivalent CSS Selector div#area_impressao, so let's stick with the later;

• That site can be a bit slow sometimes, so let's be extra tolerant and increase the HTTP timeout to 10 s;

And then we have our fixed command line:

newslinkrss \
    -p 'https://www.jaraguadosul.sc.gov.br/news/.+' \
    --http-timeout 10 \
    --follow \
    --with-body \
    --body-csss 'div#area_impressao' \
    --date-from-csss 'small.text-muted > b' \
    --csss-date-fmt '%d/%m/%Y' \
    https://www.jaraguadosul.sc.gov.br/noticias.php

... not perfect, but it gives us a very practical and usable feed!

More useful notes

Capturing good titles

The title of an item is one of the most important attributes you can get from a feed, as you probably will choose between continue reading or not based on it. newslinkrss has some strategies for finding a good title even if the source site has some very bad design choices.

If you are not following the target pages (i.e. not using option --follow), the only title available will be the anchor text. If following, newslinkrss will, by default, use the target document title with a fall back to the anchor text or description for pages that do not have titles.

Some sites have titles that are just too polluted but also have an alternate element with a descriptive text which can be used in its place. For these cases, newslinkrss has options --title-from-xpath and --title-from-csss. Both have the same effect but the former selects the element or attribute with the alternate title using a XPath expression and the later picks an element using a CSS Selector (it is not possible to select attributes with CSS). If these options are given but do not return any valid text, newslinkrss will fall back to the usual title selection.

After the title is selected, it is also interesting to remove redundant text from it. newslinkrss has an option --title-regex for this exact purpose: it accepts a regular expression with a single capture group and, if the expression matches, the captured text will be used as the title. Otherwise it will keep the original text, so we do not loose titles if something changed at the source, for example. Most common use case for this option is to remove the name of the site from article titles: it is a good design to have them in the web but, on a news reader, we do not want them using the very limited space available for item titles just to repeat information already shown in the feed title.

It is also possible to limit the length of the title, as sometimes errors in the source site can give us insanely long ones. This is done with option --max-title-length (shortcut: -l) and the default value, 150, should probably work for the most use cases.

Capturing publish dates

The date when a particular item was published is another very useful piece of information from a feed, so newslinkrss also has several ways of getting it from source pages, with availability depending on the way it is used (i.e. with or without --follow) and the information available in the HTML. Related options are the following:

• If explicitly used, options --date-from-xpath, --xpath-date-regex, and --xpath-date-fmt will allow reading dates from any element in the target page which can be found with a XPath expression. Naturally, the target page which must be downloaded with --follow; The XPath expression must return a string (from the inner text or the attributes of an element), the second is optional, but if given it must provide a regular expression with a single capture group with the date, and the third should give the date format. If no regex is given, all the string will be used and if no date format is given, the code will try some common date formats;

• If explicitly used, options --date-from-csss, --csss-date-regex, and --csss-date-fmt work in a similar way as the previous ones, but using CSS Selectors instead. They are not as powerful or flexible as XPath, but simpler, cleaner, and more suitable for HTML;

• If explicitly used, options --date-from-text and --text-date-fmt allow reading the date from the anchor text (i.e., the text inside tag <a>) associated to a particular entry in the index page; no --follow is necessary. The first option must provide a regular expression with a single capture group for the date (which allows removing non-date parts of the string) and the second option should give the date format. If the format is not given, the code will try some common date formats;

• If explicitly used, options --date-from-url and --url-date-fmt allow reading the date from the item link; this is specially interesting for sites that have URLs in format "https://example.org/posts/2020/09/22/happy-hobbit-day/" but provide no better source for a publish date. Again, no --follow is necessary. The first option must provide a regular expression with a single capture group with the date and the second option should give the date format. If the format is not given, code will try some common date formats;

• If no date was found yet and option --follow is used, dates will be read automatically from standard metadata (Open Graph, etc.) if they exists in the target page;

• If no date was found yet, but the HTTP request returned a "Last-Modified" header, assumes it as the actual last modification date (even if the server may be lying to us here).

These options are tried in this order with the first valid date being picked. This way, options explicitly included in command line have priority, with higher precedence being given to the ones which may return a "good" date. If no date options are listed, or if could not grab a date from the document, standard metadata and HTTP headers will be used (in this order).

Locale-dependent dates

Some date formats depend on the system locale, most common cases being month names (tokens %b and %B), and the date parsing options will also depend on it to interpret these dates correctly. By default, newslinkrss will use the locale set for the current user, read from environment variables, and ignore any failure if it is not available or is invalid. Option --locale allows setting an explicit locale name, so newslinkrss will use it or abort in the event of a failure. If you want to keep the default best-effort approach for a non-default locale, set environment variable LC_ALL when calling newslinkrss (i.e. call with "LC_ALL=pt_BR.UTF-8 newslinkrss <options>").

Ignoring URLs

The link pattern (-p) has a counterpart --ignore-pattern (shortcut -i) which also accepts a regular expression and makes newslinkrss ignore any matching URL. Depending on the amount of information that the website puts on the URLs, this can be used for excluding native advertisement, uninteresting sections, or other unwanted content from the feed, without support from the feed reader and without counting to the total URL limit (-n). While it is possible to add this ignore rule to the link pattern itself, using -i prevents that regular expression from becoming excessively complex and makes debugging easier. This option can be used multiple times, a URL that match any of them will be ignored.

Cleaning URL query strings

Sometimes the source page has URLs with unwanted query string parameters, like the UTM trackers, or multiple URLs differing only by irrelevant query string parameters and pointing to the same destination page (and therefore confusing the duplicate link detection). Option --qs-remove-param (shortcut -Q) may be used to fix this. If the name of a parameter matches the regular expression given in this option, that name/value pair will be removed from the URL query string. This option may be repeated many times if necessary. Example: -Q '^utm.+' (notice the anchor to only match prefixes).

Excluding body elements

When generating a complete feed we may sometimes end up including some unwanted elements from the source page into the item body, usually ads, "related news" boxes, section headers, random images, distracting formatting, unrelated links, etc. Some, but not all, of these noise sources can be removed by carefully crafting XPath expressions or CSS selectors, but for the cases where this is not possible, demand too much effort, or result in a fragile solution, we can just remove the unwanted elements explicitly.

newslinkrss has tree command line options for this:

• Option --body-remove-tag (shortcut -R) will remove all occurrences of the given tag from the feed body and move their child elements to their parents. This can be used to remove formatting while preserving the inner text (e.g. -R strong) or to remove images from the body (with -R img, as "img" elements have no children);

• Option --body-remove-xpath (shortcut -X) will remove the elements given by a XPath expression and their children. This is a good way to remove banners, divs, etc. from the generated feed;

• Option --body-remove-csss (shortcut -C) will remove the elements given by a CSS Selector and their children. This is another way to remove banners, divs, etc. from the generated and more practical when selecting element by their CSS classes.

All three options can be repeated in the command line how many times as necessary to express all required rules.

Renaming tags and attributes

Sometimes we need to replace all occurrences of a HTML tag by another one while preserving all attributes and structure; this is exceptionally common when facing sites "infected" by Google AMP and exceptionally rare for anything else. Option --body-rename-tag (shortcut: -N) exists for this exact reason; assuming that we want to replace all instances of tag amp-img by img, we can just do a -N amp-img img.

A similar use case appears when sites use lazy loading strategies for images. It is a bit common to have the image "src" attribute pointing to a placeholder image, sometimes inlined in a "data:" URL, while the URL for the actual image is in another attribute, with a script loading the image only after the user scrolls the page. Option --body-rename-attr can fix some of these cases. Assuming that a site has all src attributes for img tags in the attribute data-src, we can do --body-rename-attr img data-src src. Elements that do not have the old attribute will not be changed. If the element already has an attribute with the new name, it will be replaced. This operation always runs after --body-rename-tag and sees the DOM as already modified by it, so when renaming both tags and attributes, you must look for the new tag name.

Capturing categories

Every item of a feed can have a list of categories (the RSS name for tags or topics) and they can be pretty valuable for sorting and filtering. By default, newslinkrss tries to get them from Open Graph or quasi-standard metadata, but some sites may only put them in some other element. Options --categories-from-xpath and --categories-from-csss allow reading the categories from the DOM using XPath and CSS Selectors, respectively.

For example, assume that a site has a list of tags in an element like this:

<ul class="tags">
  <li><a href="/tag/essays">Essays</a></li>
  <li><a href="/tag/tolkien">Tolkien</a></li>
  <li><a href="/tag/the-silmarillion">The Silmarillion</a></li>
  <li><a href="/tag/unfinished-tales">Unfinished Tales</a></li>
</ul>

We can easily get them using --categories-from-csss 'ul.tags li a'.

Sometimes list of tags can be trickier. Assume another site with a list of topics in a single HTML meta tag similar to:

<meta property="topics" content="essays, tolkien, the silmarillion, unfinished tales">

These categories are in an attribute, so we can use the XPath version to get them, i.e. --categories-from-xpath '//meta[@property="topics"]/@content'. The value, however, is a single string with no markup that allow us to get the individual category names. For these cases we can use option --split-categories "," (which applies to the results of both XPath and CSSS versions) to split this string in a list of categories at every comma.

newslinkrss also does some simple cleanup for the list of categories automatically (removing spaces, putting sensible limits to the number and length of categories, etc.) to prevent some crazy situations.

Handling request language options

Some sites change their rendering, response language, date formats, etc. according to the preferred language information sent by the user's browser. By default, newslinkrss uses the "LANG" environment variable to set this language information (it is a bit of an optimization for the most common case where the system language is the same as the one of the browser used for debugging the options for a particular feed). To set a different one, you may overwrite the LANG variable or use option --lang. The later option is more flexible as it may be repeated to set several languages in order of preference (e.g. "--lang pt-BR --lang en-US --lang de-DE").

To not send any preferred language information to the server, independently of one currently set for the system, clear the LANG variable for the newslinkrss process invocation (e.g. "LANG='' newslinkrss <other options>").

Managing cookies

newslinkrss persists cookies among requests from the same program invocation and forgets them once the program finishes; this is usually the most practical choice for typical use cases, but there is an option --no-cookies to disable all cookies if it becomes a problem for a particular source.

Conversely, sites may expect a particular cookies to be set to a specific value, for example, to show news from a particular geographic region. Command line option --cookie allows the user to define customized cookies to handle these cases. This option supports the complete syntax defined by RFC 2965, but a simple name=value will work for the majority of use cases. Example: --cookie 'cookie-banner-consent-accepted=false'. This option can be repeated as many times as necessary.

If user-defined cookies are used together with option --no-cookies, the target site will have access to them, but will not be able to change or delete them (by overwriting or redefining the expiry date) or set new cookies. This results in a read-only cookie jar that can be very useful for sites that require cookies but use them to change behavior in unwanted ways after some number of pages are processed.

Setting arbitrary HTTP headers

Some sites may require unusual request options to work correctly. newslinkrss has an option --header (shortcut: -H) to set any HTTP header for the requests it sends. To use it, just pass the header in format "NAME: VALUE" (e.g. --header 'X-Clacks-Overhead: GNU Terry Pratchett'). This should not be a common requirement, however. It is also not recommended to use this option for handling language preferences and cookies, as the dedicated options --lang and --cookie will take care of the specific behavior of these headers.

Testing links

newslinkrss has an option --test that will skip the feed generation step and just print the links and titles that were captured for a particular set of options to stdout. That's a simple way to check if a pattern is working as intended.

Logging

Things will go wrong when experimenting with ugly regexes and confusing XPath expressions or when fighting unexpected changes in some website's DOM. Simplest way to see how newslinkrss is reacting internally is to increase output verbosity with option --log; default value is "warning", but "info" and "debug" will give more information like which element a XPath expression found, if a regex matched or how some date was interpreted.

This information is always printed to stderr so it will not affect the feed output written to stdout; when debugging in the terminal, remember to redirect the output to a file with the shell or command line option -o.

Error reporting

By default, newslinkrss writes exceptions and error messages to the feed output itself. This is a very practical way to report errors to the user, as this program is intended to work mostly on the background of the actual user-facing application. It is possible to disable this behavior with option --no-exception-feed (shortcut -E).

Notice that the program always return a non-zero status code on failures. Some news readers (e.g. Liferea) won't process the output in these cases and discard the feed entries with the error reports. You may need to override the status code with something like newslinkrss YOUR_OPTIONS; exit 0.

Writing output to a file

Option -o allows writing the output to an file; it is no much different than redirecting stdout, but will ensure that only valid XML with the right encoding is written.

Writing output to files and error reporting on the feed itself allows for some unusual but interesting use patterns: for example, it is trivial for a company, group, or development team to have an internal "feed server", where feeds are centrally downloaded by a cron job, saved to a web server public directory and then transparently provided to the end users. A setup with Alpine and nginx running in a LXD container is surprisingly small.

Caveats

Be very careful with escape characters! In the shell, it is recommended to use single quotes for regexes, so "\" is not escaped. This becomes more confusing if your feed reader also use escape sequences but with different or conflicting rules (e.g. Newsboat uses "\" as escapes but does not follow the same rules used by bash). When in doubt, run the command in the shell or use a wrapper script to test for any unusual behavior introduced by the program.

Some feed readers run commands in a synchronous (blocking) mode and their interface will get stuck until the command terminates. Liferea had this behavior until version 1.13.7, for example. A typical workaround is to create a script with all calls to newslinkrss that saves the generated feeds to files (see option -o), schedule this script to run from cron and configure Liferea to load the feed from the files. This solves the frozen interface problem, but requires configuring feeds in two different places.

Bugs

Yes :-)

Contributing

For this project I started an experiment: I'm using sourcehut as the primary repository for code and other tools, leaving the usual Github and Gitlab as non-advertised mirrors. Sourcehut does everything by the old-school way and most features just work without an user account. Check the project page there to see how it works.

If this sounds too strange, just clone the repository with an git clone https://git.sr.ht/~ittner/newslinkrss, publish your fork somewhere and send an email with the branches to be merged to ~ittner/[e-mail] (that's correct: tildes and slashes are valid characters for email addresses).

If you change the code, please run in through pyflakes for static analysis and black to ensure a consistent formatting.

License

Copyright (C) 2020 Alexandre Erwin Ittner [e-mail]

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Contact information

• Author: Alexandre Erwin Ittner
• Email: [e-mail]
• Web: https://www.ittner.com.br