slackbuilds_ponce/system/fish/README

fish (Friendly Interactive Shell)

fish is a user friendly command line shell for UNIX-like systems.
fish includes case insensitive completions, a multiline editing
system, a new and simplified key binding system, and a large number
of command specific completions.

This package will potentially conflict with the /usr/games/fish
binary from the y/bsdgames package.  In a stock installation with
default PATH ordering, /usr/bin should be checked before /usr/games,
so it shouldn't be an issue, but we thought it was worth noting
just in case.

NOTES:

This SlackBuild automatically adds fish to /etc/shells.

To use fish as your login shell, run this command:

 $ chsh -s /usr/bin/fish

To remove it from the /etc/shells (in case of fish removal), run:

 $ su -c "sed -ri '\|^/usr/bin/fish$|d' /etc/shells"

To use fish_update_completions see README.Slackware from man-db
SlackBuild or typically (as normal user or root):

 $ fish
 $ source /etc/profile.d/man-db.sh
 $ fish_update_completions