nexus3 配置systemd

要将 Nexus3 配置为 systemd 服务，请按照以下步骤进行操作：

1. 编写 Nexus3 的 systemd 配置文件 `/etc/systemd/system/nexus.service`，内容如下：

[Unit]
Description=Nexus3 Service
After=network.target

[Service]
Type=forking
LimitNOFILE=65536
ExecStart=/opt/nexus/bin/nexus start
ExecStop=/opt/nexus/bin/nexus stop
User=nexus
Group=nexus
Restart=on-abort

[Install]
WantedBy=multi-user.target

请注意，您需要将 `ExecStart` 和 `ExecStop` 中的 `/opt/nexus` 替换为您实际的 Nexus3 安装位置。

2. 执行以下命令启动 Nexus3 服务并设置开机自启：

systemctl daemon-reload
systemctl start nexus
systemctl enable nexus

3. 验证 Nexus3 是否已正常启动：

systemctl status nexus

如果 Nexus3 正常运行，则该命令的输出应该类似于下面的内容：

● nexus.service - Nexus3 Service
   Loaded: loaded (/etc/systemd/system/nexus.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2021-09-10 16:18:14 UTC; 2min 14s ago
  Process: 2363 ExecStop=/opt/nexus/bin/nexus stop (code=exited, status=0/SUCCESS)
  Process: 2370 ExecStart=/opt/nexus/bin/nexus start (code=exited, status=0/SUCCESS)
 Main PID: 2373 (java)
    Tasks: 79 (limit: 1074)
   CGroup: /system.slice/nexus.service
           └─2373 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java -Dinstall4j.jvmDir=/usr/lib/jvm/java-8-openjdk-amd64/jre -Dexe4j.moduleName=/opt/nexus/bin/nexus -Dexe4j...

Sep 10 16:18:17 ubuntu1804 nexus[2370]: WrapperManager: Initializing...
Sep 10 16:18:17 ubuntu1804 nexus[2370]: --> Wrapper Started as Daemon
Sep 10 16:18:18 ubuntu1804 nexus[2370]: Java Service Wrapper Standard Edition 64-bit 3.5.43
Sep 10 16:18:18 ubuntu1804 nexus[2370]:   Copyright (C) 1999-2016 Tanuki Software, Ltd. All Rights Reserved.
Sep 10 16:18:18 ubuntu1804 nexus[2370]:     http://wrapper.tanukisoftware.com
Sep 10 16:18:18 ubuntu1804 nexus[2370]: Licensed to Sonatype Inc. for Nexus Repository Manager
Sep 10 16:18:18 ubuntu1804 nexus[2370]: WrapperManager: JVM #1
Sep 10 16:18:18 ubuntu1804 nexus[2370]: Running a 64-bit JVM.
Sep 10 16:18:18 ubuntu1804 nexus[2370]: WrapperManager: Registering shutdown hook

这样，您就已经成功地将 Nexus3 配置为 systemd 服务了。