Redis Basic Commands and Key Operations Tutorial
This article provides a concise tutorial on essential Redis commands, covering basic operations, database selection, key management, expiration settings, and practical examples demonstrated through the Redis CLI, including how to list keys with patterns, check existence, and clear databases.
The article begins with a brief invitation to follow the “DevOps Architecture Practice” account for daily technical updates.
1. Basic Redis Commands
127.0.0.1:6379> ping
PONG
127.0.0.1:6379> DBSIZE
(integer) 0
127.0.0.1:6379> SELECT 5 # Switch to database 5 (databases are indexed from 0 to 15)
OK
127.0.0.1:6379[5]> DBSIZE
(integer) 0
127.0.0.1:6379[5]> set k1 v2
OK
127.0.0.1:6379[5]> set k2 v1
OK
127.0.0.1:6379[5]> DBSIZE
(integer) 2
Delete all data in the current database: FLUSHDB
127.0.0.1:6379[5]> FLUSHDB
OK
127.0.0.1:6379[5]> DBSIZE
(integer) 0
2. Redis Key Operations
A. Syntax: keys pattern
Purpose: Find all keys matching the given pattern; the pattern can use wildcards.
* matches zero or more characters (e.g., keys * lists all keys – not recommended in production).
? matches a single character (e.g., keys he?lo matches hello and heolo ).
127.0.0.1:6379> set k1 v1
OK
127.0.0.1:6379> set k2 v3
OK
127.0.0.1:6379> keys *
1) "k2"
2) "k1"
127.0.0.1:6379> set hello hello
OK
127.0.0.1:6379> set heolo heolo
OK
127.0.0.1:6379> keys he?lo
1) "heolo"
2) "hello"
B. exists
Check whether a key exists.
127.0.0.1:6379> EXISTS hello
(integer) 1
127.0.0.1:6379> EXISTS helol
(integer) 0
127.0.0.1:6379> EXISTS heolo
(integer) 1
C. expire
Set a key’s time‑to‑live (TTL) in seconds; returns 1 if the timeout was set, 0 otherwise.
D. ttl
Returns the remaining TTL of a key in seconds.
-1: key has no expiration (never expires).
-2: key does not exist.
127.0.0.1:6379> ttl k1 # The key currently has no expiration
(integer) -1
127.0.0.1:6379> EXPIRE k1 20 # Set k1 to expire after 20 seconds
(integer) 1
127.0.0.1:6379> ttl k1 # 15 seconds remaining
(integer) 15
127.0.0.1:6379> ttl k1 # 11 seconds remaining
(integer) 11
127.0.0.1:6379> ttl k1 # 2 seconds remaining
(integer) 2
127.0.0.1:6379> ttl k1 # After expiration, the key is removed
(integer) -2
127.0.0.1:6379> keys * # Verify remaining keys
1) "heolo"
2) "k2"
3) "hello"
----------------------end---------------------
Recommended Reading:
Redis Advantages and Remote Client Connections
Redis Data Backup and Restoration
Setting Up Redis Sentinel
Redis Sentinel and Master‑Slave Replication
Detailed Summary of Redis Configuration Files
Practical DevOps Architecture
Hands‑on DevOps operations using Docker, K8s, Jenkins, and Ansible—empowering ops professionals to grow together through sharing, discussion, knowledge consolidation, and continuous improvement.
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