Backup script using git

Backup.rb

#!/usr/bin/env ruby

medium = ARGV.shift || 'Spinn'
user = ENV['USER']
hostname = `hostname`.chomp

path = "/media/#{user}/#{medium}"
rc = "#{ENV['HOME']}/.bashrc-backup"

unless File.directory?(path)
  raise RuntimeError, "please mount #{medium}"
end

git_path = "#{path}/git/#{user}-#{hostname}-home.git/"

unless File.directory?(git_path)
  raise RuntimeError, "repository does not exist: #{git_path}"
end

ENV['BACKUP_RUNNING'] = "true"
ENV['GIT_DIR'] = git_path
ENV['prompt_char']="backup >"
ENV['HISTFILE']="#{ENV['HOME']}/.backup_bash_history"

puts "Starting Backup env"
commands = <<-EOMAN
  . ~/.bashrc
  unalias -a
  alias s="git status --untracked-files=all --ignore-submodules=all"
  alias ss="s | less"
  alias a="git add -A"
  alias r="git reset HEAD"
  alias ci="a ~/.gitignore && git commit -m"
  i() {
    git rm --cached -r $1
    echo $1 >> ~/.gitignore
  }
  snap() {
    ci "snapshot $(date -R)"
  }
  alias -p
  echo "i=ignore given files"
  echo 'awaiting you command'
EOMAN
File.open(rc, 'w') { |f| f.write commands }
exec(%Q~bash --rcfile #{rc} -i~)