Bash 2.0 For Loop Counter

This is the syntax you can use for a simple for loop counter in bash version 2 (e.g. on Apple OS X version 10.4):

for ((i = 1; i <= 5; i++)); do echo $i; done

Otherwise for i in {1..5}; do ... is a simpler syntax that works in newer bash versions. More details can be seen at Vivek Gite's Bash For Loop Examples.

Ruby Command Line Parsing

require "optiflag"
require "log"

module Options extend OptiFlagSet
  optional_switch_flag "debug"
  optional_flag "date"
  usage_flag "help"

  and_process!
end

if Options.flags.debug?
  Log.on
  Log.log "debug mode on"
end

if Options.flags.date != nil
  puts "-date #{Options.flags.date}"
end

Here is the official documentation with an example.