Ruby version requirement auto discovery wrapper / "conditional shebang"

rubyscript.sh

#!/bin/sh
for ruby in $(which -a ruby); do
  if $ruby -e "exit 1 if RUBY_VERSION < '2.1'"; then
    exec $ruby -x "$0" "$@"
  fi
done
echo "No suitable ruby 2.1+ interpreter found" >&2
exit 1
#!ruby

puts "Hey there from: #{RUBY_VERSION}"
puts "Because ruby -x skips until the first occurence of #!ruby"
puts "The ruby code here will be executed just fine"