OSH is a bash-compatible shell, and is part of the Oil project (http://www.oilshell.org).
This file describes how to install OSH. (It's in the release tarball and also published on the web.)
If you haven't already done so, extract the tarball:
tar -x --xz < oil-0.6.pre5.tar.xz
cd oil-0.6.pre5
Either install as /usr/local/bin/osh:
./configure # completes very quickly
make # 30-60 seconds
sudo ./install
or install as ~/bin/osh:
./configure --prefix ~
make
./install
The latter doesn't require root access, but it requires ~/bin to be in your PATH.
NOTE: Out-of-tree builds are NOT currently supported, so you have to be in the oil-0.6.pre5 directory.
OSH behaves like a POSIX shell:
$ osh -c 'echo hi'
hi
This parses and prints a syntax tree for the 'configure' script.
osh -n configure
Roughly speaking, you need:
(I want to eventually remove the GNU requirements and require just POSIX sh instead).
Optional:
Debian/Ubuntu and derivatives:
sudo apt install build-essential libreadline-dev
Alpine Linux:
apk add libc-dev gcc bash make readline-dev
OSH hasn't been tested on non-Linux systems, but eventually it should run on any POSIX-compatible system.
./configure --help will show the options. Right now, the only significant options are --prefix and --{with,without}-readline.