What are some alternatives?
When comparing Rush and rc - a shell, you can also consider the following products
zsh - The Z shell (Zsh) is a Unix shell that can be used as an interactive login shell and as a powerful command interpreter for shell scripting.
DASH - DASH is a secure, blockchain-based global financial network which offers private transactions.
GNU Bourne Again SHell - Bash is the shell, or command language interpreter, that will appear in the GNU operating system.
Nu Shell - A modern shell written in Rust
fish - The friendly interactive shell.
Xiki - Xiki makes the command line friendlier and more powerful.