Sending Webmentions with a Simple Shell Script

I came across a convenient way to send webmentions from my terminal using a simple Bash script. This page on the IndieWeb wiki includes a shell script one-liner. It references an older version of the webmention standard, but I was able to figure it out and get it working with my setup. I have the following in a file titled send-wm:

#!/usr/bin/env bash

my_url="$1"
target_url="$2"

curl -i -d "source=$my_url&target=$target_url" $(curl -i -s "$target_url" | grep 'rel="webmention"' | grep -o -E 'https?://[^ ">]+' | sort | uniq)

The example had rel="http://webmention.org/" instead of rel="webmention", which is the current standard. It also included an extra step — sed 's/rel="webmention"//'. I assume this was originally supposed to read something like sed 's/rel="http:\/\/webmention.org\/"//', which would be necessary to make sure there is only one "http(s)" to grep for. At any rate, that part doesn't appear to be currently necessary. (UPDATE: I edited the IndieWeb wiki to reflect the current version of this script!)

This script can be used as follows. Note that to do this, you will first need to run sudo chmod +x send-wm to make the script executable:

./send-wm <your_url> <target_url>

The basic command to send a webmention using cURL looks like this:

curl -i -d "source=$your_url&target=$target_url" $targets_webmention_endpoint

This script inserts the provided source/target URLs into the statement, and the part inside the parentheses evaluates to the webmention endpoint from the target page.

I also added this to my webmentions tutorial — I like to do that so all my webmention info is in one place. I regularly update this, and there's a table of contents to jump to specific sections.

Future Plans

I imagine it's possible to make a version of this that only needs the URL for the post sending the mention, and can parse out a list of URLs linked from that page and try sending webmentions to each, handling any failure gracefully. If I get around to doing that, I'll write another post and add it to the tutorial. Until next time!