Fish has support to autocomplete the options of any command at the shell. (This is sometimes called tab completions.) For example, when I type
ls - and
TAB, Fish shows me the options available for the
ls command. This works even when you've typed out part of an option. Fish generates this information by parsing all the man pages installed on your system.
If you find that Fish autocomplete is not working for the options of a command, that can be fixed easily by asking Fish to reindex from man pages. The Fish function that you need to run for this is:
I recently installed Git. Since Git is infamous for its myriad command-line options I missed having autocomplete at the shell for Git command options. After running
fish_update_completions, I could get autocomplete for options of all Git commands! The icing on top was to discover that Fish could autocomplete options even for my Git aliases!
Tried with: Fish 2.2.0