Custom tab completions in oksh

Software

A chat with @zoomosis made me realise that I never talked about oksh’s tab completion, which is half the reason I use and spruik it as a daily driver shell.

For a recap, I moved to oksh on my Macs and BSD boxes so I could keep roughly the same .kshrc config on each machine I own, even my ancient nostalgia boxes. FreeBSD notably doesn’t include a Kornshell, but macOS and NetBSD do. oksh adds a couple of nice features, while still being fast and lightweight.

oksh’s tab completion is the other reason. Using set statements you can define tab completions for commands you specify. I like to keep these in a separate file, and reference it in my .kshrc:

[ -f ~/.oksh_completions ] && . ~/.oksh_completions

The syntax is simple. Here are some common FreeBSD commands:

set -A complete_geli -- attach backup configure detach
set -A complete_iocage -- create destroy fetch get list rename restart set start stop
set -A complete_pkg -- clean info install lock search unlock update upgrade
set -A complete_pkgin -- autoremove avail install full-upgrade pkg-info remove search update
set -A complete_zfs -- clone create list receive send set snapshot
set -A complete_zpool -- create export import scrub set

Because it’s a shell script, you could do this for SSH hosts:

_SSH_HOSTS=$(awk '/^Host/{ print $2 }' ~/.ssh/config)
set -A complete_mosh -- $_SSH_HOSTS
set -A complete_scp -- $_SSH_HOSTS
set -A complete_ssh -- $_SSH_HOSTS

And for services:

_SERVICES=$(ls -1 /etc/rc.d/)
    
case `uname` in
    FreeBSD)
        _SERVICES="$_SERVICES $(ls -1 /usr/local/etc/rc.d/)"
esac

There’s a lot you could configure here, and I’ve probably only scratched the surface.

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