Creates swap file on linux

setup_swap.rb

# Usage:
# curl -s https://gist.githubusercontent.com/cristianbica/10347658/raw/setup_swap.rb | sudo ruby - multiplier [remove_current_swap]
# multiplier - when creating the swap will multiply the current RAM with the multiplier
# remove_current_swap - true to remove current swap in /swapfile (default false)
# Ex: curl -s https://gist.githubusercontent.com/cristianbica/10347658/raw/setup_swap.rb | sudo ruby - 2
# Ex: curl -s https://gist.githubusercontent.com/cristianbica/10347658/raw/setup_swap.rb | sudo ruby - 2 true


if ARGV[1] and ARGV[1]=="true"
  puts "Removing swap from swapfile as requested ..."
  `swapoff /swapfile`
  `rm -rf /swapfile`
  `sed -i".bak" '/swapfile/d' /etc/fstab`
  puts "DONE"
end

if File.exists?("/swapfile")
  puts "/swapfile exists. Exiting"
else
  multiplier = (ARGV[0] || 2).to_f
  `cat /proc/meminfo  | grep MemTotal` =~ /(\d+)/
  current_ram = $1.to_i*1024
  swapsize = (current_ram*multiplier).to_f
  puts "Creating a swapfile of #{(swapsize/1024/1024/1024).round(2)}G .."
  `fallocate -l #{swapsize.to_i} /swapfile`
  `chmod 600 /swapfile`
  `mkswap /swapfile`
  `swapon /swapfile`
  `echo '/swapfile none swap defaults 0 0' >> /etc/fstab`
  puts "DONE"
end