Redis PUBSUB command is an introspection command that allows to inspect the state of the Pub/Sub subsystem. It is composed of subcommands that are documented separately.
Following is the basic syntax of Redis PUBSUB command.
redis 127.0.0.1:6379> PUBSUB subcommand [argument [argument ...]]
Array reply, a list of active channels.
redis 127.0.0.1:6379> PUBSUB CHANNELS (empty list or set)