post_install() {
	grep -qe '^/bin/zsh$' etc/shells || echo '/bin/zsh' >> etc/shells
	grep -qe '^/usr/bin/zsh$' etc/shells || echo '/usr/bin/zsh' >> etc/shells
}

post_upgrade() {
	post_install
}

pre_remove() {
	sed -i -r '/^(\/usr)?\/bin\/zsh$/d' etc/shells
}