Installing LyX from Source

I've been using LyX as my go-to document editor since its early days, and I really love it. Until recently, installation and upgrades (on Linux Mint) were a no-brainer. I could either install/update the package from the Canonical repositories (which tend to lag behind the current release) or get the latest version from a PPA (which, sadly, is no longer maintained). Yesterday I was running LyX 2.4.0 RC3, the version in the Canonical repo for Ubuntu 22.04 (the basis for the current version, 22, of Linux Mint), and ran into an issue. To see if it had already been resolved, I decided to upgrade to the current LyX version, 2.4.1. That entailed compiling it from source for the first time ever.

The process, while slow, was almost smooth. I did run into one speed bump, an error message (from the APT package manager, not from LyX) that was a trifle cryptic. Some serious googling turned up the solution. I thought I'd document the compilation process below in case other Mint (or Ubuntu) users want to try installing from source for the first time.

1. Open the Software Sources system app and make sure that Official Repositories > Optional Sources > Source code repositories is turned on. (On my first go-around it was turned off, which produced the cryptic error message I mentioned.)
2. Download the source tarball and signature file from the LyX download site. Verify the tarball as described here.
3. Unzip the tarball into a directory located wherever you want to keep the source code (if in fact you choose to keep it). I'm pretty sure you can delete the source folder after compiling and installing, but I'm hanging onto it for now.
4. In a terminal in that directory, run sudo apt-get build-dep lyx to install all necessary prerequisites. I found this useful tip in the LyX wiki. This was the step that generated the error message on the first attempt, due to my having skipped step 1 above.
5. Open the INSTALL.autoconf text file in the source folder and follow the directions (summarized here).
1. Run configure (which takes a while).
2. Run make (which takes an eternity).
3. Optional: run make check and verify all tests were passed.
4. Run make install to install the program.

Regarding the last step, I normally install LyX for all users on the system (which is just me, since this is my home PC). So I ran make install as root. If you just want it for the account under which you are logged in, you can run it without escalating privileges.

That's all there is to it.