How I Generate My RSS Feed

I only just now started supplying an RSS feed to you fine people! You + can subscribe to it at www.senders.io/blog/feed.rss!

I decided rather than manually generating the file contents I’d hook + into my pre-existing publish scripts to be able to generate the RSS + file.

Publishing blog posts - shell scripts ftw

In My Markdown -> HTML Setup I + touch on how I publish my markdown files into HTML for this blog. But + what I don’t really touch on is the shell scripts that tie the + whole process together.

What I have is two, now three, scripts that feed the whole + process:

publish-blog.sh - the main script
compile-md.sh - generates the HTML output
update-feed.sh - generates/appends the RSS feed

The update-feed.sh script is the new one I just + added.

publish-blog.sh is the primary interface, I supply the + date of the post and the path to the md file and that calls compile and + update to automate the entire process.

Without going into TOO much detail you can view the latest versions of + the scripts at git.senders.io/senders/senders-io/tree/.

But the gist of the scripts is I parse out the necessary details, + find/replace some tokens in template files I have setup for headers and + footers, and concat the outputs into the final output HTML files, and now + RSS feed.

update-feed.sh

Source File: git.senders.io/senders/senders-io/tree/update-feed.sh

This script is pretty interesting. I didn’t want to deal with any XML + parsers and libraries to just maintain a proper XML rss file and push + items into the tree. Rather, I just follow a similar setup to my markdown + generation. I leverage some temporary files to hold the contents, a + static temp file for the previously generated content, and at the end + swap the temp file with the real file.

I take in an input of the publish date (this is the date from the + publish script), the title, and the HTML file path. These are all already + variables in the publish script, but also something I can manually supply + if I need to publish an older article, or something I wrote directly in + HTML.

The core of the script is found here:

PUBDATE=$(date -d "$1" -R)
+TITLE=$2
+FILE_PATH=$3
+PERMALINK=$(echo "${FILE_PATH}" | sed -e "s,${TKN_URL_STRIP},${URL_PREFIX},g")
+LINK=$(echo "${PERMALINK}" | sed -e "s,${TKN_INDEX_STRIP},,g")
+
+# Generate TMP FEED File Header
+
+cat -s $FILE_RSS_HEADER > $FILE_TMP_FEED
+sed -i -E "s/${TKN_BUILDDATE}/${BUILDDATE}/g" $FILE_TMP_FEED
+sed -i -E "s/${TKN_PUBDATE}/${PUBDATE}/g" $FILE_TMP_FEED
+
+# Generate TMP Item File
+
+cat -s $FILE_RSS_ITEM_HEADER > $FILE_TMP_ITEM
+sed -i -E "s~${TKN_TITLE}~${TITLE}~g" $FILE_TMP_ITEM
+sed -i -E "s/${TKN_PUBDATE}/${PUBDATE}/g" $FILE_TMP_ITEM
+sed -i -E "s,${TKN_PERMALINK},${PERMALINK},g" $FILE_TMP_ITEM
+sed -i -E "s,${TKN_LINK},${LINK},g" $FILE_TMP_ITEM
+sed -n "/<article>/,/<\/article>/p" $FILE_PATH >> $FILE_TMP_ITEM
+cat -s $FILE_RSS_ITEM_FOOTER >> $FILE_TMP_ITEM
+
+# Prepend Item to items list and overwrite items file w/ prepended item
+## In order to "prepend" the item (so it's on top of the others)
+## We need to concat the tmp item file with the existing list, then
+## we can push the contents over the existing file
+## We use cat -s to squeeze the blank lines
+cat -s $FILE_ITEM_OUTPUT >> $FILE_TMP_ITEM
+cat -s $FILE_TMP_ITEM > $FILE_ITEM_OUTPUT
+
+# Push items to TMP FEED
+cat -s $FILE_ITEM_OUTPUT >> $FILE_TMP_FEED
+
+# Push RSS footer to TMP FEED
+cat -s $FILE_RSS_FOOTER >> $FILE_TMP_FEED
+echo $FILE_TMP_FEED
+
+# Publish feed
+cat -s $FILE_TMP_FEED > $FILE_RSS_OUTPUT
+
+echo "Finished generating feed"
+

Some key takeaways are:

sed lets you do regex with delimiters that AREN’T / so + you can substitute something that shouldn’t actually ever show up in + your regex. For me that is ~.
I always forget you can use sed to extract between tokens - which + is how I get the CDATA for the RSS: sed -n + "/<article>/,/<\/article>/p"
mktemp is really REALLY useful - and I feel is under + utilized in shellscripting

The obvious cracks are:

I rely SO much on sed that it’s almost certainly going + to break
I don’t have much other flag control to do partial generation - so + if I need to do something either starting partway through or not finish + the full process, I don’t have that.
Sometimes things can break silently and it will go through, there + is no verification or like manual checking along the way before + publishing the feed.rss

The final two can easily be managed by writing the feed to a location + that isn’t a temp file and I can manually do the cat -s + $FILE_TMP_FEED > www/blog/feed.rss myself after I check it + over.

But for now I’ll see if I ever have to redo it. I don’t think anyone + will actually sub to this so I don’t really need to care that much if I + amend the feed.

Where to put the feed URL

I never intended to provide an RSS feed. I doubt anyone but me reads + this, and from my previous experience with gemini feed generation was a + bit of a headache.

A quick aside: I really only decided thanks to Mastodon. I was + thinking during the Twitter meltdown “what if twitter but RSS” (I know + super unique idea). But basically like a true “microblog”. And some OSS + tools to publish your blog. This got me reading the RSS spec and looking + into it more - which then lead me down the using the RSS readers more (in + conjunction with gemini, and Cortex podcast talking about using RSS + more).

But I’ve decided to just put the RSS feed in the blog index, on my + homepage, and that’s it. I don’t need it permanently in the header.

Conclusion

I didn’t have much to share here, it doesn’t make too much sense to + write a big post on what can be explained better by just checking out the + shell scripts in my git source. The code speaks better than I ever + could.

I really, really like shell scripting.