^R is more powerful, though; it matches at any point in previous commands, not just at the beginning.
> The lack of this functionality actually really kills my ability to use any other shell.
You can achieve that behavior in readline (which is used by bash, python shell, etc.) by changing the up/down arrows from previous-history/next-history to history-search-backward/history-search-forward. In ~/.inputrc:
"\e[A": history-search-backward
"\e[B": history-search-forward
Note that you can still use ^P/^N for previous-history/next-history (or you can remap "\C-p"/"\C-n" as well).That's how it works in Fish as well.
user@system ~> echo wow
wow
user@system ~> echo something
something
user@system ~> wow█
...press the up arrow and the current line becomes... user@system ~> echo wow█ (reverse-i-search)`w': echo wow
Hit return to execute, or any motion keys to start editing. It was the first thing I missed in Fish. > echo w̲ow
Hit return to execute, or any motion keys to start editing. As long as you don't move sideways, you can repeatedly press up or down to navigate history. The underline is actually a highlight hinting at the substring match in the line.The difference is that typing an additional character after having moved in the history will start editing, appending the character to the line, instead of appending to the criteria.
What I miss in all of them is looking for a fuzzy match instead of a substring match.
In fish you just type 'w' hit the up arrow and then hit enter to execute or any motion keys to edit. The same number of keypresses as well.
Am I misunderstanding?
zsh definitely has this command, which I absolutely adore to be honest. ^R is one of my favourite features of the shell in general.
As you said at the end, Fish does have this. I don't know if it's full-featured enough for you though.
> Control+R. It is annoying to have to guess how much you must type before hitting the up arrow, instead of having it dynamically displayed
When you start typing a command-line in Fish that matches a previously-typed command, it automatically shows the rest of the line as an available completion, and pressing ^F or the right arrow will complete it for you. The lack of this functionality actually really kills my ability to use any other shell.
> Currently, it is impossible to pass a multi-line string from a command substitution as a single argument
Not actually true. If you set IFS to '' then that disables command substitution line splitting. That said, it is not well-known and is rather awkward. This is a known pain point with Fish today.
> More extensibility in general. I'd like to be able to customize my shell just as much as I can customize my WM. Probably more.
It's really hard to know what you're asking for here. What isn't extensible enough for you? What do you wish you could do that you can't?