Ubuntu中自定义服务 + 修改优先级 ____ 开机脚本

upstart把应用封装成系统服务

http://blog.fens.me/linux-upstart/

永驻后台之程序或者脚本

# /etc/init/cs.conf
# cat /etc/issule -> 14.04 或者 Debian （可能有debian 由的systemd的方案， 查看最下面） GNU/Linux 8 已验证
# 启用 sudo start cs
# 停止 sudo stop cs

description "iibul_service"
author "iibull"

start on startup
stop on shutdown

respawn

console output

# if to run App, then
#exec /work/myServ  #启用一个后台的应用程序
# if you want to script
env var=bar
export var

pre-start script
        logger "pre-start: before: var=$var"
        var=pre-start
        export var
        logger "pre-start: after: var=$var"
end script

post-start script
        logger "post-start: before: var=$var"
        var=post-start
        export var
        logger "post-start: after: var=$var"
end script

script
        logger "script: before: var=$var"
        var=main
        export var
        sleep 60000
        logger "script: after: var=$var"
end script

post-stop script
        logger "post-stop: before: var=$var"
        var=post-stop
        export var
        logger "post-stop: after: var=$var"
end script

%E4%B8%AD%E8%87%AA%E5%AE%9A%E4%B9%89%E6%9C%8D%E5%8A%A1/
在Ubuntu中定义一些服务，可以对该服务进行全局控制，比较常见的就是用sudo service servcie_name start/stop/restart 进行服务的启停

在/etc/init.d/目录下面定义控制服务的脚本

service_name="service_name"
service_script_path="service_script_path"

start()
{
    echo "$service_name service start"
    chmod a+x $service_script_path && nohup ./$service_script_path
}

stop()
{
    echo "$service_name service stop"
    server_process_id=`ps -aux | grep $service_name | cut -d " " -f 6`
    echo "server_process_id="server_process_id
    kill -9 $server_process_id
}

case $1 in
start)
    start
    ;;
stop)
    stop
    ;;
restart)
    echo "resert the $service_name"
    stop
    start
    ;;
*)
    echo "undefine operation"
    ;;
esac

自己写了个服务脚本扔到/etc/init.d/，service启停服务目前OK了。 
使用update-rc.d命令可以设置服务2-5级别开机自动启动。 

参照 /etc/init.d/README文档。

### BEGIN INIT INFO
# Provides: skeleton
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Should-Start: $portmap
# Should-Stop: $portmap
# X-Start-Before: nis
# X-Stop-After: nis
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# X-Interactive: true
# Short-Description: Example initscript
# Description: This file should be used to construct scripts to be
#                    placed in /etc/init.d.
### END INIT INFO

然后使用命令update-rc.d default myserv 来设置我自定义的服务开机自启动

在rc2-5.d目录下生成了S20myserv

改变优先级别

/etc/rc2.d/S20redis-server
/etc/rc2.d/S21rtds2
2是Ubuntu默认的runlevel，S表示Start的意思。
20的优先级比21高，也就是说S20服务先启动，然后才轮到S21服务启动。

删除原来运行级的启动软链接：
sudo update-rc.d -f redis-server remove
sudo update-rc.d -f rtds2 remove

设置新的服务启动优先级：
sudo update-rc.d redis-server defaults 20
sudo update-rc.d rtds2 defaults 21

例如我们要添加一个开机脚本 运行 

# 采自于 http://minecraft.gamepedia.com/Tutorials/Ubuntu_startup_script
#为服务制定专用的用户组 和 分配服务组目录权限
sudo adduser --system --no-create-home --home /srv/minecraft-server minecraft
sudo addgroup --system minecraft
sudo adduser minecraft minecraft # this adds user "minecraft" the group "minecraft"
sudo chown -R minecraft.minecraft /srv/minecraft-server

#写开机脚本 /etc/init/minecraft-server.conf
#create and edit the start/stop script creating a new file under /etc/init/minecraft-server
#(NOT /etc/init.d but /etc/init (without the .d) ) 
#make sure that you save the file as minecraft-server.conf
sudo nano /etc/init/minecraft-server.conf

#脚本内容如下
## description "start and stop the minecraft-server"

start on runlevel [2345]
stop on runlevel [^2345]

console log
chdir YOUR_INSTALLATION_DIRECTORY
setuid minecraft
setgid minecraft

respawn
respawn limit 20 5

exec /usr/bin/java -Xms1536M -Xmx2048M -jar minecraft_server.jar nogui

#脚本各行的解释信息如下
-----------------------------------------------------------------
# description "start and stop the minecraft-server" <-- Adds a tip to what this script does.

start on runlevel [2345] <-- 何时开启服务. Runlevels 2, 3, 4, and 5 are the "normal operation".
stop on runlevel [^2345] <-- 何时停止服务. The ^ means NOT.

console log <-- Log的提示方式
chdir YOUR_INSTALLATION_DIRECTORY <-- 改变当前的活动目录.
setuid minecraft <-- 切换到 minecraft 用户
setgid minecraft <-- 切换到 minecraft 用户组

respawn <-- 当检测到程序异常时， 允许程序自动重启
respawn limit 20 5 <--自动重启 20次/5秒内

exec /usr/bin/java -Xms1536M -Xmx2048M -jar minecraft_server.jar nogui <-- Below...
'exec' > 执行命令
'/usr/bin/java' > 调用的程序
'-Xms1536M' > Sets minimum allocated memory limit.
'-Xmx2048M' > Sets MAXIMUM allowable memory limit.
'-jar minecraft-server.jar' > Tells Java to run the jarfile minecraft_server.jar
'nogui' > Tells minecraft-server.jar to run without a GUI. (Graphical screen).

#现在是的脚本生效
sudo initctl reload-configuration

#开关服务
sudo start minecraft-server
sudo stop minecraft-server
#查看日志
sudo tail /var/log/upstart/minecraft-server.log

###########################################################################################
#在有systemd的系统内，可以这样做，15.04之后systemd 被取消了。

sudo gedit /etc/systemd/system/minecraft-server.service

[Unit] 
Description=start and stop the minecraft-server 

[Service]
WorkingDirectory=/srv/minecraft-server
User=minecraft
Group=minecraft
Restart=on-failure
RestartSec=20 5
ExecStart=/usr/bin/java -Xms1536M -Xmx1536M -jar minecraft_server.jar nogui

[Install]
WantedBy=multi-user.target
Alias=minecraft-server.service

sudo service minecraft-server start
sudo systemctl enable minecraft-server
systemctl status minecraft-server.service

SSH 客户端执行GUI程序，实现在客户端上

DISPLAY=:0.0
执行你的程序即可。