How do I use Ruby for shell scripting?

Question

I have some simple shell scripting tasks that I want to do

For example: Selecting a file in the working directory from a list of the files matching some regular e

Answer 1

The above answer are interesting and very helpful when using Ruby as shell script. For me, I does not use Ruby as my daily language and I prefer to use ruby as flow control only and still use bash to do the tasks.

Some helper function can be used for testing execution result

#!/usr/bin/env ruby
module ShellHelper
  def test(command)
    `#{command} 2> /dev/null`
    $?.success?
  end

  def execute(command, raise_on_error = true)
    result = `#{command}`
    raise "execute command failed\n" if (not $?.success?) and raise_on_error
    return $?.success?
  end

  def print_exit(message)
    print "#{message}\n"
    exit
  end

  module_function :execute, :print_exit, :test
end

With helper, the ruby script could be bash alike:

#!/usr/bin/env ruby
require './shell_helper'
include ShellHelper

print_exit "config already exists" if test "ls config"

things.each do |thing|
  next if not test "ls #{thing}/config"
  execute "cp -fr #{thing}/config_template config/#{thing}"
end