add bash completion

[lucasew]

I use bash as my daily driver shell and missed the completions so I tried making one.

It doesn't show the descriptions of the commands but lists them already.

This is my first time hacking around completions tho.

[ianthehenry]

Hey neat thanks! I’m on vacation this week but I’ll take a look when I get back.

[ianthehenry]

Hey! Okay sorry I completely forgot to look at this when I got back from vacation.

I tried to test this with the extremely old version of bash that ships with macOS and found that it didn't work. The error I get is:

$ sd <TAB> bash: [: -v: unary operator expected
realpath: : No such file or directory
bash: COMP_WORDS: bad array subscript

Specifically that's:

$ bash --version
GNU bash, version 3.2.57(1)-release (arm64-apple-darwin22)
Copyright (C) 2007 Free Software Foundation, Inc.

Although the error here appears to be from /bin/[. I suspect this is just a difference between BSD test and GNU coreutils test? By replacing [] checks with [[ ]] checks we can remove the dependence on the rest of the system and keep things in pure bash. It looks like that [] construct does work on Linux with a newer bash.

Slightly unrelated but I would replace the ls | while read with a glob expansion? I'm not sure if there's a difference that I'm not seeing but a glob seems more natural.