Redis CLI Basics

The Redis command line interface, called redis-cli, is the fastest way to talk to a Redis server. You type a command, press Enter, and Redis answers within a millisecond. Developers use it to learn commands, test ideas, inspect data, and fix problems on live servers.

The Walkie-Talkie Analogy

Think of redis-cli as a walkie-talkie. You press the button, speak one short message, and the other side replies at once. Each message is a single command, and each reply is a single answer.

  You (redis-cli)                    Redis Server
  ┌──────────────┐   PING            ┌──────────────┐
  │  Type a      │ ───────────────►  │  Reads the   │
  │  command     │                   │  command     │
  │              │ ◄───────────────  │  Sends reply │
  └──────────────┘   PONG            └──────────────┘

Starting redis-cli

Run the tool with no options to connect to a server on your own machine at port 6379.

$ redis-cli
127.0.0.1:6379>

Add options to reach a remote server or to log in with a password.

$ redis-cli -h 192.168.1.20 -p 6380 -a MySecret

Passing a password with -a stores it in your shell history. Type AUTH after connecting when you work on shared machines.

Your First Commands

127.0.0.1:6379> PING
PONG
127.0.0.1:6379> ECHO "Hello Redis"
"Hello Redis"
127.0.0.1:6379> SET course "Redis"
OK
127.0.0.1:6379> GET course
"Redis"

PING checks that the server is alive. ECHO returns the text you send. SET and GET store and read a value.

Understanding Replies

Redis replies in a few simple shapes. Learning these shapes helps you read any command output.

Reply Type        Example Output            Meaning
────────────────  ────────────────────────  ──────────────────────────
Simple string     OK                        Command succeeded
Bulk string       "Redis"                   A stored value
Integer           (integer) 5               A count or number result
Nil               (nil)                     Key does not exist
Array             1) "a"  2) "b"            A list of results
Error             (error) ERR ...           Command failed

Getting Help Inside the Shell

Type HELP followed by a command name to see its syntax and a short description.

127.0.0.1:6379> HELP SET

  SET key value [NX|XX] [GET] [EX seconds|PX milliseconds|...]
  summary: Set the string value of a key

Type CLEAR to wipe the screen. Type QUIT or press Ctrl+D to leave.

Switching Databases

A Redis server offers 16 numbered databases, from 0 to 15. Database 0 is the default. Use SELECT to move between them.

127.0.0.1:6379> SELECT 2
OK
127.0.0.1:6379[2]>

The number in square brackets shows your current database.

Handy Command Line Options

Run One Command Without Entering the Shell

$ redis-cli GET course
"Redis"

Repeat a Command

Use -r for the repeat count and -i for the delay in seconds.

$ redis-cli -r 5 -i 1 INCR visitors
(integer) 1
(integer) 2
(integer) 3
(integer) 4
(integer) 5

Watch Live Statistics

$ redis-cli --stat

This option prints a new line of keys, memory, clients, and request counts every second.

Practical Example – Checking a Login Counter

Goal: Confirm that the app records every login.

Step 1:  redis-cli
Step 2:  GET logins:today        → "152"
Step 3:  (user logs in on the website)
Step 4:  GET logins:today        → "153"

Result: The counter moved by one, so the app writes to Redis correctly.

Key Points

• redis-cli connects to a server and runs commands one at a time.
• Use -h, -p, and -a to set host, port, and password.
• Replies come as strings, integers, nil, arrays, or errors.
• HELP shows command syntax without leaving the shell.
• SELECT switches between the 16 default databases.
• Options such as -r, -i, and --stat save time during testing.