Use wordexp to support super fancy expansions

- Expands environment variables, e.g. $HOME -> /home/tina

- Expands tildes, e.g. ~/bin -> /home/queso/bin

- Performs command substitution, e.g. `date +%F` -> 2022-01-16
                                  or $(date +%F) -> 2022-01-16

ruby/Gemfile

@@ -1,2 +1,4 @@
 source 'https://rubygems.org'
 ruby '3.1.0'
+
+gem 'wordexp', '~> 0.1'

ruby/Gemfile.lock

@@ -1,11 +1,13 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    wordexp (0.1.1)
 
 PLATFORMS
   arm64-darwin-21
 
 DEPENDENCIES
+  wordexp (~> 0.1)
 
 RUBY VERSION
    ruby 3.1.0p0

ruby/main.rb

@@ -3,7 +3,7 @@
 require 'English'
 require 'open3'
 require 'readline'
-require 'shellwords'
+require 'wordexp'
 
 require './builtins'
 require './colours'
@@ -92,9 +92,9 @@ class Shell
     exit 0 if line.nil? # EOF, ctrl-d
     return if line.empty? # no input, no-op
 
-    args = Shellwords.split(line)
+    args = Wordexp.expand(line)
     cmd = args.shift
-    logger.verbose "Words: #{cmd} #{args.inspect}"
+    logger.verbose "Parsed command: #{cmd} #{args.inspect}"
     if @builtins.builtin?(cmd)
       logger.verbose "Executing builtin #{cmd}"
       @builtins.exec(cmd, args)