rush - the really uninteractive shell

Rush is designed to run POSIX scripts, and run them fast. Think of it as a Rust dash.

I know that the name is overused, but it's too good to pass up.

// TODO:

• Simple command execution ls -ltr
• Pipes exa | grep cargo
• Exit status logic ! false && ls || date
• Redirection
  • File descriptor to another ls error 2>&1
  • To/from file date > time.txt < Cargo.toml wc
  • Appending >>
  • Here-docs <<
  • Raw, non-io file descriptors 4>&7
• Async execution &
• Shell builtins
  • Normal built-ins
    • alias unalias
    • cd
    • etc
  • Special built-ins
    • exit
    • export
    • exec
    • etc
• Expansions
  • Tilde expansion ls ~
  • Parameter expansion
    • Basic expansion echo ${var:-other}
    • String length echo ${#var}
    • Suffix/prefix removal echo ${var%%pattern}
  • Command substitution
  • Arithmetic expansion
• Variables
• Quotes
• IFS
• Functions
• Control flow if for while case etc
• Expand this to-do list

Decisions to make

• Should this shell replicate commands that are typically built-in but also have system alternatives?