Updating tlmgr on Ubuntu/Linux Mint

[Willow Liquorice]

Hello,

I run TeXLive on Linux Mint, but I've been unable to update or install 
new TeXLive packages for quite some time because tlmgr is outdated. I 
would use update-tlgmr-latest, but it is common on Ubuntu for the 
kpsewhich command the script runs to return filesystem root, which 
doesn't seem very helpful.

There are instructions for this eventuality, involving adding a TeXLive 
path to $PATH, but I am unsure about which path is needed. I think the 
Ubuntu package fiddles with where things are installed a bit, which 
doesn't make the answer obvious.

I hope someone here can help me out.

Best wishes,
	Willow