Command completion for :sh

[vp2177]

Typing :sh l<Tab> should display completions for (example) longcommand, ls, ln, etc... based on executables available in PATH, in addition to file/directory name completion.

Similar to, but distinct from #6717

[pascalkuthe]

I don't think that's possible, what commands are available depends in the system shell and there is no unified way to obtain completions from those. Crawling $PATH for binaries (if we assumed that there are no builtin shell commands which is not a good assumption at all) is way too slow and super problematic so I don't think thus can be implement

[vp2177]

It can be implemented, that's not the question (it's implemented in other editors like Vim). Is it a good idea? I am saying yes because it's a (minor) improvement to user experience

[the-mikedavis]

It can be implemented, that's not the question

Well, Pascal described a way to do it - we're just concerned about the performance: blocking the prompt for a while to scan the PATH is not a good UX. Also, if you're going to assert this it would be helpful to at least link to the code where another editor implements this.

It looks like Kakoune crawls PATH and has a nice way of caching the file lookups per directory: https://github.com/mawww/kakoune/blob/019fbc5439ad884f172c324ebc928463eab9bc74/src/file.cc#L534-L600. It takes a stat of each directory and caches the commands until a directory's mtime changes. The initial lookup could still be a little slow for large PATHs though - it would be nice to figure out the completion candidates async but I think this would be a much larger change. (I think we've discussed that previously but I can't find the issue/discussion.)

[pvarga-dni]

Crawling $PATH for binaries (if we assumed that there are no builtin shell commands which is not a good assumption at all) is way too slow and super problematic so I don't think thus can be implement

As for shell built-ins, this is not a great solution, but maybe Helix could complete a hard-coded list of POSIX standard built-ins. If the user's shell has additional ones, those won't be completed. Not ideal when the user's shell isn't POSIX compliant, though...

[mo8it]

Shell completion for Fish can be implemented pretty easily by using the complete --escape -C "…" command. I can implement that if you want.

I wasn't able to find an equivalent for Bash.