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Atomic Linux Distributions

How to change the default shell in fedora silverblue?

sudo usermod --shell $(which fish) $(id -un)

Mutable Linux Distributions

sudo chsh -s $(which fish) $(id -un)

You have to add the path of fish into /etc/shells, if you get the error message "chsh: /usr/bin/fish is an invalid shell".

Log out and then log in (or simplify reboot) for the change to take effect.