使用 Linux 时经常用到 ` service mysql restart ` 等命令, 方便进行服务的操作, 具体的服务是怎么写的呢,通过以下示例将了解以下内容:

• 如何写一个简单的服务
• 服务异常关闭时能自动开启配置

简单的示例

nano /lib/systemd/system/xx.service

1. [Unit]
2. Description=Check GPU INFO by chenwei # 服务描述
3. Wants=network-online.target # 服务依赖于网络
4. After=network-online.target
6. [Service]
7. Type=simple
8. ExecStart=/root/shell/agent/chkgpu # 服务开启时执行脚本
9. ExecReload=/bin/kill -HUP $MAINPID # 服务重新加载时执行脚本
10. RestartSec=5s # 自动启动间隔时间
11. Restart=on-failure # 在什么情况下会自动重启
13. [Install]
14. WantedBy=multi-user.target
16. [Unit]
17. Description=Advanced key-value store
18. After=network.target
20. [Service]
21. Type=forking
22. ExecStart=/usr/local/redis/bin/redis-server /usr/local/redis/etc/redis.conf
23. ExecStop=/bin/kill -s TERM $MAINPID
24. PIDFile=/var/run/redis_6379.pid
25. Restart=always
26. RestartSec=5s
27. Restart=on-failure
30. [Install]
31. WantedBy=multi-user.target
32. Alias=redis.service

nginx 示例

1. [Unit]
2. Description=A high performance web server and a reverse proxy server
3. After=network.target
5. [Service]
6. Type=forking
7. PIDFile=/var/run/nginx.pid
8. #ExecStartPre=/usr/local/nginx/sbin/nginx
9. ExecStart=/usr/sbin/nginx
10. ExecReload=/usr/sbin/nginx -s reload
11. ExecStop=-/sbin/start-stop-daemon --quiet --stop --retry QUIT/5 --pidfile /run/nginx.pid
12. TimeoutStopSec=5
13. KillMode=mixed
15. [Install]
16. WantedBy=multi-user.target

常用命令

1. systemctl enable --now nginx.service # 立刻开启并开机启动
3. systemctl daemon-reload #重新加载
5. systemctl enable nginx.service #开机时启动
6. systemctl disable nginx.service #开机时禁用
7. systemctl list-unit-files|grep enabled #已启动服务列表
8. systemctl --failed #启动失败服务列表

wssh

1. file=/lib/systemd/system/myssh.service mv $file $file.bak cat «EOF »$file
3. [Unit] Description=Web SSH server by chenwei. pip install webssh Wants=network-online.target
4. After=network-online.target
6. [Service] Type=simple ExecStart=wssh ExecReload=/bin/kill -HUP $MAINPID
7. RestartSec=5s
8. Restart=on-failure
10. [Install] WantedBy=multi-user.target
12. EOF cat $file

issh

1. file=/usr/bin/issh
2. mv $file $file.bak
3. cat <<EOF >>$file
4. #!/bin/bash
5. wssh
6. autossh -M 10111 -NR 0.0.0.0:11111:localhost:22 pc@1.10sh.cn
9. EOF
10. cat $file
12. chmod +x $file
14. file=/lib/systemd/system/issh.service
15. mv $file $file.bak
17. cat <<EOF >>$file
19. [Unit]
20. Description=autossh shell to connect to my server by chenwei. #sudo apt install autossh
22. Wants=network-online.target
23. After=network-online.target
25. [Service]
26. Type=simple
27. ExecStart=/usr/bin/issh
28. ExecReload=/bin/kill -HUP
29. RestartSec=5s
30. Restart=on-failure
32. [Install]
33. WantedBy=multi-user.target
36. EOF
37. cat $file
40. systemctl enable --now issh.service
42. systemctl status issh.service

pweb

使用python 启动一个简单的 http 文件服务。

1. sudo -i
4. file=/home/pweb.sh
5. mv $file $file.bak
6. cat <<EOF >>$file
9. #!/bin/bash
10. python3 -m http.server
12. EOF
13. cat $file
15. chmod +x $file
17. file=/lib/systemd/system/pweb.service
18. mv $file $file.bak
19. cat <<EOF >>$file
22. [Unit]
23. Description=Simple python pweb by chenwei.
25. Wants=network-online.target
26. After=network-online.target
28. [Service]
29. Type=simple
30. ExecStart=/home/pweb.sh
31. ExecReload=/bin/kill -HUP
32. RestartSec=5s
33. Restart=on-failure
35. [Install]
36. WantedBy=multi-user.target
39. EOF
40. cat $file
42. systemctl enable --now pweb.service
44. systemctl status pweb.service

原文地址：https://www.toutiao.com/a7005179018735518246/

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