Question: How to check if Redis is running?

Answer

To check if Redis is running, you can use the redis-cli command-line interface or the systemctl command on Linux systems.

1. Using redis-cli:

You can run the following command in a terminal window:
```
redis-cli ping
```
If Redis is running, it will return "PONG". If it's not running, you'll get an error message.

2. Using systemctl:

On Linux systems that use systemctl for service management, you can run the following command in a terminal window:
```
systemctl status redis
```
This will show you the current status of the Redis service. If Redis is running, you should see output similar to the following:
```
● redis.service - Redis In-Memory Data Store
Loaded: loaded (/lib/systemd/system/redis.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2023-04-17 08:27:46 UTC; 3h 23min ago
Docs: http://redis.io/documentation,
man:redis-server(1)
Main PID: 12345 (redis-server)
Tasks: 4 (limit: 16384)
Memory: 22.8M
CGroup: /system.slice/redis.service
└─12345 /usr/bin/redis-server 127.0.0.1:6379
```
If Redis is not running, you'll see an error message indicating that the service is inactive or failed.

In addition to these methods, you can also check the Redis logs to see if there are any errors or warnings. The default location for Redis logs is /var/log/redis/redis-server.log. You can view the last few lines of the log file using the tail command:
```
sudo tail -f /var/log/redis/redis-server.log
```
This will show you the last few lines of the log file in real-time. If Redis is running, you should see messages indicating that it's accepting connections and processing commands. If there are any errors or warnings, they'll be displayed here as well.

Overall, these methods should help you determine whether Redis is running or not and troubleshoot any issues that may arise.