I hope that your recovery will be swift. Whenever you feel ready to take this on, try the following:
I’m stuck on several fronts. E.g. I cannot upgrade to a compatible version of X-code (or cannot find the needed legacy link). […] Cd be this stale os version not the way forward.
I’m still using an older macOS version than yours, so don’t give up hope yet.
If the
xcode-select --install command isn’t working from Terminal on your computer, then an alternative approach would be to download the command-line development tools installer directly from Apple in your browser. To do that, use your Apple ID to log in at
https://developer.apple.com/downloads/index.action ; using the search pane there, enter “command line tools”, then select the appropriate Yosemite-targeted .dmg package to download.
Once you’ve downloaded the command-line development tools installer and have run it, run the
xcode-select -p command in Terminal; if it has installed correctly, that command will show the folder in which it has been installed, and you’ll be able to continue from step 3 in
the previously posted list.
Please note that in my last reply, the link to the MacPorts 2.9.0 Yosemite installer is incorrect; the correct link is
here.