$ sudo apt-get install redis-server

$ redis-server --daemonize yes

$ redis-cli
127.0.0.1:6379> ping
PONG

$ ps -ef | grep redis-server
barwe    18165     1  0 14:26 ?        00:00:00 redis-server *:6379
barwe    23228 11728  0 14:43 pts/6    00:00:00 grep redis-server

$ redis-cli
127.0.0.1:6379> config set reqiurepass 123456
127.0.0.1:6379> auth 123456

gem "redis"

$redis = Redis.new(
  :host => "127.0.0.1",
  :port => 6379,
  :password => "123456",
)

$ rails c
irb(main):001:0> $redis.set(:age, 23)
=> OK
irb(main):003:0> $redis.get(:age)
=> "123"