Ruby/Database/dbm

require "bdb"
db = BDB::Btree.create("e.db", nil, BDB::CREATE)
db["earth"] = "M"
db["water"] = "A"
db["air"] = "s"
db["fire"] = "P"
db.each { |k,v| puts k }
puts db["water"]
db.close

require "bdb"
db = BDB::Hash.create("r2.db", nil, BDB::CREATE)
db["W"] = "i"
db.close
db = BDB::Hash.open("r2.db", nil, "r")
db["W"]
db.close

require "dbm"
d = DBM.new("data")
d["123"] = "123"
puts d["123"]  
d.close
puts d["123"]             # RuntimeError: closed DBM file
e = DBM.open("data")
e["123"]       
w=e.to_hash    
e.close
e["123"]                  # RuntimeError: closed DBM file
w["123"]

require "dbm"
DBM.open("r") do |db|
  db["t"] ="W"
  db[23] = "F"
end
DBM.open("r") do |db|
  puts db["t"]
  puts db["23"]
end
p Dir["r.*"]