Get free disk space

free.rb

#!/usr/bin/env ruby

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'json'
  gem 'sys-filesystem'
end

require 'sys/filesystem'

def fs_mounts
  File.read('/etc/fstab').lines.select {|l| l.start_with?('/') }.map do |ml|
    next if ml.split(' ')[2] == 'swap'
    ml.split(' ')[1]
  end.compact
end

def sys_mounts(mtypes: ['ext4']) = Sys::Filesystem.mounts.select {|m| mtypes.include? m.mount_type }

def space_available(mount, unit: :mb)
  stat = Sys::Filesystem.stat(mount)

  percent = 100 - (100.0 * stat.bytes_available.to_f / stat.bytes_total.to_f)

  [stat.bytes_available / 1024 / 1024, percent ]
end

sys_mounts.each do |mount|
  puts "'#{mount.mount_point}' -> %d MB available ; %0.1f %%  full" % space_available(mount.mount_point)
end