Ruby OptParse example

db_backup.rb

#!/usr/bin/env ruby

# A sample use of optparse to parse command line arguments/flags
# Sample run:
#   $> ./db_backup.rb -u bijan.hoomand --password blahblah -s local --verbosity 3
#   {:user=>"bijan.hoomand", :password=>"blahblah", :server=>"127.0.0.1", :verbosity=>3}
#
#   $> ./db_backup.rb -u bijan --password blahblah --server dev -v 5 --iteration
#   ./db_backup.rb:40:in `<main>': invalid argument: -u bijan (OptionParser::InvalidArgument)

# If you want to have mandatory arguments, without any - or --, have a look at:
# https://stackoverflow.com/questions/2449171/how-to-parse-an-argument-without-a-name-with-rubys-optparse

require 'optparse'

servers = {
    local: '127.0.0.1',
    dev: '192.168.1.10',
    prod: '52.40.42.5'
}.freeze

options = {}

op = OptionParser.new do |opts|
    opts.banner = 'Usage: db_backup.rb [options]'
    # create a switch
    opts.on('-i', '--iteration', 'end of iteration?') do
        options[:iteration] = true
    end
    # create a flag with validation
    # raises exception if username is not like firstname.lastname
    opts.on('-u', '--user USER', /^.+\..+$/, "server's username") do |user|
        options[:user] = user
    end

    opts.on('-p', '--password PASSWORD', "server's password") do |password|
        options[:password] = password
    end

    # user can enter '-s dev' and it translates to servers[dev]
    opts.on('-s', '--server SERVER', servers, 'server to connect to') do |server|
        options[:server] = server
    end

    # built in converstion to given class
    # LEVEL given will be converted to Integer
    opts.on('-v', '--verbosity LEVEL', Integer, 'verbosity level') do |level|
        options[:verbosity] = level
    end
end

op.parse!

puts options.inspect