Because macOS' `apropos` is just using grep, and we only need
a prefix match for __fish_describe_command, we can shave off
some ok total execution time here.
No longer uses the __fish_apropos hack on every version of macOS.
Juat Catalina+.
The whatis database generated and replaced daily is 2 megabytes on
my computer, and in ~/.cache on a home dir might wind up on a net
mount or something annoying. or, definitely it's backed up by default.
It's wiser to throw that junk in with other cache files on the system
aka DARWIN_USER_CACHE_DIR, and only use the XDG directory if
someone specifically configured that.
Mainly, this just means at least it won't automatically get backed
up by Time Machine and stuff every day, which is no big deal but
y'know...
Rearranged stuff a little to not shell out every time.
This actually *worked* in my tests which confuses me.
It really shouldn't, `apropos -foo` will complain about "-o" not being
a valid option.
It should be `apropos -- -foo`.
Now, of course there are awful apropos implementations, so let's see
if someone complains
In the new __fish_apropos, makewhatis is run explicitly to generate the
whatis database. However this can be a little slow. Run it in the
background, after the apropos call completes so as to avoid a weird
race.
This means that descriptions may not be available the first time the
user invokes it, but that's better than appearing to hang for a while.
override MANPATH used by apropos with local whatis database and update it once a day
get rid of xargs
Created __fish_apropos and fixed __fish_complete_man to use that as well
moved macos apropos comment
