rocketmq linux 安装

### RocketMQ Installation Guide for Linux

#### Prerequisites
Before installing RocketMQ on a Linux system, ensure that the following prerequisites are met:

- Java Development Kit (JDK) version 8 or higher is installed.
- A stable internet connection.

To verify JDK installation, execute:

java -version

If not already present, install OpenJDK using package managers like `yum` or `apt-get`.

For CentOS/RHEL/Fedora systems:

sudo yum install java-1.8.0-openjdk-devel

For Debian/Ubuntu systems:

sudo apt update && sudo apt install openjdk-8-jdk-headless

#### Downloading RocketMQ
Download the latest release of Apache RocketMQ from the official website or via command line tools such as wget or curl. For instance,

wget http://mirrors.estointernet.in/apache/rocketmq/4.9.3/rocketmq-all-4.9.3-bin-release.zip
unzip rocketmq-all-4.9.3-bin-release.zip -d /opt/
cd /opt/rocketmq

Ensure directory permissions allow execution rights where necessary.

#### Configuring Environment Variables
Add environment variables to simplify starting services later on. Edit `/etc/profile`, adding lines at the end:

export ROCKETMQ_HOME=/opt/rocketmq
export PATH=$ROCKETMQ_HOME/bin:$PATH

Apply changes immediately without logging out/in again with source command:

source /etc/profile

#### Starting Name Server and Broker Service
Start the nameserver first since brokers need it running before they can start successfully:

nohup sh bin/mqnamesrv &

Check its status afterward:

tail -f ~/logs/rocketmq/namesrv.log

Once confirmed operational, proceed to launch broker service similarly but specify name server address explicitly through configuration file (`conf/broker.conf`) under property `namesrvAddr`. Then run:

nohup sh bin/mqbroker -n localhost:9876 autoCreateTopicEnable=true &

Verify operation by checking logs located typically within user home folder inside path similar to this one mentioned above regarding nameservers'.

#### Testing Setup
After both components have started properly, test setup completeness utilizing provided scripts found in `$ROCKETMQ_HOME/tools` subdirectory which includes examples demonstrating how messages could be sent/received between producers/consumers over topics created earlier during broker initialization phase when enabling automatic topic creation feature was set true previously while configuring broker properties.

--related questions--

1. What versions of JDK support RocketMQ?
2. How does one configure multiple instances of RocketMQ Brokers?
3. Can you explain more about message persistence options available in RocketMQ configurations?