Today I tried to switch to another shell.
First I tried fish, and used chsh -s fish to change fish to default. After some time I found it cannot use ~/.bashrc (&& needs to be replaced by and).
Because I prefer to reusing ~/.bashrc, I found zsh which seems an easier one and followed this documentation to switch to zsh.
While I was running sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)", suddenly it asked me to enter Password:. I entered the root password but got PAM: Authentication failure.
Then I tried chsh -s bash and chsh -s zsh, it always asked me for a password and threw PAM: Authentication failure (not system password). I can't figure this out.