Ability have the shell wait until a script returns a non zero

wait-for

#!/usr/bin/env ruby

require 'optparse'

options = {
  retries: 10,
  delay: 1
}

parser = OptionParser.new do |opts|
  opts.banner = "Usage: example.rb [options]"

  opts.on("-c", "--command THING", "Required: Command to execute") do |command|
    options[:command] = command
  end

  opts.on("-r", "--retry COUNT", Integer, "Number of retries to perform (default: #{options[:retries]})") do |retries|
    options[:retries] = retries
  end

  opts.on("-d", "--delay COUNT", Integer, "Seconds to wait for each check (default: #{options[:delay]})") do |delay|
    options[:delay] = delay
  end
end

parser.parse!

tries = 0
successful = false

command, retries, delay = options.values_at(:command, :retries, :delay)

if command.nil?
  puts parser
  exit 1
end

while tries < retries && successful == false
  system command

  if $?.success?
    successful = true
  else
    tries += 1
    puts "Failed (#{tries} of #{retries})"
    sleep delay
  end
end

if successful
  puts "Success! Executing next script."
  exit 0
else
  puts "Failed to run '#{command}' command after #{tries} attempts."
  exit $?.exitstatus
end