# Cheat Sheet #day2 - Redis Commands

Redis commands are the fundamental building blocks for interacting with Redis, an open-source, in-memory data structure store used as a database, cache, and message broker. These commands enable users to perform a wide range of operations on Redis data structures such as strings, hashes, lists, sets, and sorted sets. Here are some key Redis commands and their uses:

### Key Redis Commands:

1.  String Commands:

    -   `SET key value`: Sets the value of a key.
    -   `GET key`: Retrieves the value of a key.
    -   `INCR key`: Increments the integer value of a key by one.
2.  Hash Commands:

    -   `HSET key field value`: Sets the value of a field in a hash.
    -   `HGET key field`: Retrieves the value of a field in a hash.
    -   `HGETALL key`: Retrieves all fields and values in a hash.
3.  List Commands:

    -   `LPUSH key value`: Inserts a value at the head of a list.
    -   `RPUSH key value`: Inserts a value at the tail of a list.
    -   `LPOP key`: Removes and returns the first element of a list.
    -   `LRANGE key start stop`: Retrieves a range of elements from a list.
4.  Set Commands:

    -   `SADD key member`: Adds a member to a set.
    -   `SMEMBERS key`: Retrieves all members of a set.
    -   `SREM key member`: Removes a member from a set.
5.  Sorted Set Commands:

    -   `ZADD key score member`: Adds a member to a sorted set, or updates its score if it already exists.
    -   `ZRANGE key start stop [WITHSCORES]`: Retrieves a range of members in a sorted set, optionally with scores.
    -   `ZREM key member`: Removes a member from a sorted set.
6.  Key Commands:

    -   `DEL key`: Deletes a key.
    -   `EXISTS key`: Checks if a key exists.
    -   `EXPIRE key seconds`: Sets a timeout on a key.
7.  Transaction Commands:

    -   `MULTI`: Marks the start of a transaction block.
    -   `EXEC`: Executes all commands issued after MULTI.
    -   `DISCARD`: Discards all commands issued after MULTI.
8.  Pub/Sub Commands:

    -   `PUBLISH channel message`: Publishes a message to a channel.
    -   `SUBSCRIBE channel`: Subscribes to a channel to receive messages.
9.  Connection Commands:

    -   `PING`: Tests if a connection to the server is still alive.
    -   `AUTH password`: Authenticates to the server with a password.