I am getting a strange message whenever I run sudo, ever since upgrading my MS Windows 10 WSL Ubuntu 16 –> Ubuntu 18.
The message is
sudo: setrlimit: Function not implemented
The upgrade seemed to go very well, with the only hickup coming at the very end, when it complained that the ssh configuration files had been modified. After some strangeness with trying to compare configuration files, I finally just told it to overwrite the old files, and things seemed to finish smoothly.
Best Answer
It turns out that steeldriver had the right of it. The issue was caused by my out-of-date version of MS Windows 10. Removing and re-installing WSL didn't do any good.
However, once I was finally able to find a path that would upgrade the version of MS Windows, then it was trivial to install WSL, followed by doing a "Get" from the MS App Store to install the latest Ubuntu.
After the typical initialization, getting my version of Ubuntu fully current was just a matter of typing
sudo apt update -y && sudo apt upgrade -y && sudo apt autoremove -y.