About 98% of common POSIX shell usage is covered by fish, right down to identical syntax. (Not everything is.)
Biggest tip for fish switchers: set fish as your terminal's shell instead of changing your login shell.
Biggest tip for fish switchers: set fish as your terminal's shell instead of changing your login shell.
That's an interesting idea - I will try that. This bit me recently when I used Migration Assistant to move from a Mac with Catalina to one with Big Sur; my login shell was still set to the path for fish installed via Homebrew, but none of those packages were copied over. I managed to hack around it by copying bash into that location so that I could reinstall Homebrew and fish to finish repairing things.
You can use Fish on any system where Nix runs on, btw. For example, I use it on Synology's DSM.
By default your terminal program uses that, but most terminals let you override that to be something else.
Perhaps not having to run chsh on a new machine, which I have to run -h on to remember how to use ever few years.
Being new increases the chances of doing something like that that breaks the shell. It's annoying to fix for those of us with experience, and extremely difficult to fix for those without experience. It gets even worse when you consider that some distros like Ubuntu don't set a root password, so you can't log into the root account without sudo, which requires your user to have a functional login shell. I wouldn't want a new user to paint themselves into a corner where the only way to get their desktop working again is to remember how to boot into single user mode or boot from removable media and mount their hard drive. Doubly so if their Linux desktop is their only PC; it's going to be really annoying if the only way to write removable media to boot from is the machine that's currently broken.