What's the best free open source chatbot therapist that runs on Linux?

Emacs doctor is very rudimentary but can be surprisingly useful.

eliza is in linux standard repositories, for example on ubuntu 20.04:

sudo apt-cache search eliza

sudo apt install -y libchatbot-eliza-perl

dpkg-query -L libchatbot-eliza-perl

/usr/share/doc/libchatbot-eliza-perl/examples/simple