When I was going back and forth between bash and zsh more, I started keeping a ~/.commonrc file that uses only some subset of syntax that's compatible with both

When I was going back and forth between bash and zsh more, I started keeping a ~/.commonrc file that uses only some subset of syntax that's compatible with both, and sourcing that file from both .bashrc + .zshrc . Things like adding to the PATH, aliases (well, ones that work in both bash and zsh), shell functions, etc, can just go in .commonrc and be forgotten. It's nice.