我按照本指南安装了 no-ip 动态 ddns： https://www.noip.com/support/knowledgebase/installing-the-linux-dynamic-update-client/
我让服务运行
sudo /usr/local/bin/noip2
但是我希望服务在启动时启动，我尝试将以下脚本添加到 /etc/init.d/noip2.sh
#######################################################
#! /bin/sh
# . /etc/rc.d/init.d/functions # uncomment/modify for your killproc
case "$1" in
start)
echo "Starting noip2."
/usr/local/bin/noip2
;;
stop)
echo -n "Shutting down noip2."
killproc -TERM /usr/local/bin/noip2
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
#######################################################
其次是：
sudo chmod +x /etc/init.d/noip2.sh
sudo update-rc.d noip2.sh defaults
现在我应该能够使用以下命令启动该服务
sudo service noip2 start
但我没有。当我运行时，journalctl -xe我得到以下信息：
-- Unit noip2.service has begun starting up.
Nov 03 12:36:11 media systemd[3111]: noip2.service: Failed to execute command: Exec format error
Nov 03 12:36:11 media systemd[3111]: noip2.service: Failed at step EXEC spawning /etc/init.d/noip2.sh: Exec format error
-- Subject: Process /etc/init.d/noip2.sh could not be executed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- The process /etc/init.d/noip2.sh could not be executed and failed.
--
-- The error number returned by this process is 8.
Nov 03 12:36:11 media systemd[1]: noip2.service: Control process exited, code=exited status=203
Nov 03 12:36:11 media systemd[1]: noip2.service: Failed with result 'exit-code'.
Nov 03 12:36:11 media systemd[1]: Failed to start noip2.service.
-- Subject: Unit noip2.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
用户 PerDuck 的更新信息：我在尝试您的解决方案时收到以下错误... :( 尝试添加
RestartSec=30
至少它现在一直在尝试，但仍然无法启动。我仍然可以使用 sudo /usr/local/bin/noip2 启动它
错误：
Nov 03 23:26:42 media systemd[1]: noip2.service: Service hold-off time over, scheduling restart.
Nov 03 23:26:42 media systemd[1]: noip2.service: Scheduled restart job, restart counter is at 5.
Nov 03 23:26:42 media systemd[1]: Stopped noip2 service.
Nov 03 23:26:42 media systemd[1]: noip2.service: Start request repeated too quickly.
Nov 03 23:26:42 media systemd[1]: noip2.service: Failed with result 'start-limit-hit'.
Nov 03 23:26:42 media systemd[1]: Failed to start noip2 service.
答案1
从 Ubuntu 15.04 开始，控制后台进程（以及更多）的标准方法是systemd。我建议从init.d脚本切换到systemd 单元：
/etc/systemd/system/noip2.service创建包含以下内容的文件（并删除您的init.d脚本）：
[Unit]
Description=noip2 service
[Service]
Type=forking
ExecStart=/usr/local/bin/noip2
Restart=always
[Install]
WantedBy=default.target
然后发出
sudo systemctl daemon-reload
了解systemd新的单元（systemd缓存单元文件并且此命令重新systemd考虑其缓存）。
现在您可以尝试启动和停止您的单元并查看其状态：
sudo systemctl status noip2
sudo systemctl start noip2
sudo systemctl status noip2
sudo systemctl stop noip2
sudo systemctl status noip2
要让设备在启动时启动，您需要使能够它：
sudo systemctl enable noip2
要在启动时禁用自动启动，您必须禁用那个单位：
sudo systemctl disable noip2
大多数时候五个命令足以控制一个单位的行为：
systemctl start $unit # starts a unit NOW
systemctl stop $unit # stops a unit NOW
systemctl status $unit # shows status
systemctl enable $unit # starts a unit at boot time (but not NOW)
systemctl disable $unit # stops autostart (but doesn't stop the unit NOW)
您还可以启用自动启动并立即启动该设备，或者禁用自动启动并立即停止它：
systemctl enable --now $unit # enable and start in one go
systemctl disable --now $unit # disable and stop in one go
更新
一些研究表明noip2跑步是一种守护进程即当你启动它时，它会创建另一个在后台运行的进程（所谓的分叉)，前台进程立即返回（退出）。这就是 init.d 脚本和 systemd 单元失败的原因：它们启动后就noip2立即退出。因此，systemd 尝试一遍又一遍地重新启动它，但无济于事。（默认情况下，systemd 在 10 秒左右内最多重新启动进程 5 次，然后放弃并使其处于失败状态。）
告诉 systemd 该单元属于类型分叉添加行
Type=forking
就像[Service]我在上面的代码片段中所做的那样。这告诉 systemd预计主进程立即返回，而是观察由 生成（分叉）的进程noip2。