我制作了一个网络应用程序来关闭计算机的屏幕，虽然有几种不同的技术，但是非常简单：
我有一个html / js前端，它检测按钮单击（屏幕打开/屏幕关闭），该按钮通过ajax将选项发送到PHP后端
然后，PHP通过TCP端口连接，将选项发送到用golang编写的程序
然后，我的golang程序执行命令以关闭/打开屏幕。 它运行的命令是（“ xset -display：0 dpms force off”）
我遇到的问题是该命令仅在在终端中运行golang程序时才有效，但是当我将其设置为服务时，该命令将不起作用。
这是golang代码：
package main
import (
"os/exec"
"net"
"fmt"
"bufio"
)
func main() {
fmt.Println("Launching server")
ln, _ := net.Listen("tcp", ":7777")
fmt.Println("Listening...
")
for {
// accept connection on port
conn, _ := ln.Accept()
fmt.Println("New connection")
// listen for message ending in
message, _ := bufio.NewReader(conn).ReadString('
')
rec := string(message)
// remove trailing
rec = rec[:len(rec)-1]
fmt.Println("Message Received: ", "\""+rec+"\"")
returnMessage := "fail"
if (rec == "screensOff") {
fmt.Println("Turning off screens...")
//execute screens off command
cmd := exec.Command("xset", "-display", ":0", "dpms", "force", "off")
stdout, err := cmd.Output()
if err != nil {
fmt.Println(err.Error())
} else {
fmt.Println(string(stdout))
returnMessage = "done"
}
} else if (rec == "screensOn") {
fmt.Println("Turning on screens...");
//execute screens on command
cmd := exec.Command("xset", "-display", ":0", "dpms", "force", "on")
stdout, err := cmd.Output()
if err != nil {
fmt.Println(err.Error())
} else {
fmt.Println(string(stdout))
returnMessage = "done"
}
returnMessage = "done"
}
conn.Write([]byte(returnMessage + "
"))
conn.Close()
fmt.Println("Connection closed
")
}
}
相关的PHP代码：
<?php
function sendServiceMessage($message) {
$host = "localhost";
$port = 7777;
$timeout = 30;
// connect to service
$socket = fsockopen($host, $port, $errnum, $errstr, $timeout);
if (!is_resource($socket)) {
exit("connection fail: ".$errnum." ".$errstr);
}
else {
// send message
fputs($socket, $message."
");
// receive return message
$recieved = "";
while (!feof($socket)) {
$recieved .= fgets ($socket, 1024);
}
}
// close connection
fclose($socket);
if ($recieved == "done") {
return true;
}
return false;
}
sendServiceMessage("screensOff");
我使用systemd来设置服务，因此在构建程序并将其放在/usr/bin/中之后/
...$ go build screenControl.go
...$ sudo cp screenControl /usr/bin/screenControl
I can run the screenControl program in the terminal, and select "screens off" in the web app and it all works as expected:
...$ screenControl
Launching server
Listening...
New Connection
Message Received: "screensOff"
Turning off screens...
Connection closed
然后，我创建了一个systemd单位文件（/etc/systemd/system/screenControl.service）:
[Unit]
Description=Screen control service
[Service]
ExecStart=/usr/bin/screenControl
Restart=on-abort
[Install]
WantedBy=multi-user.target
于是我启动服务并检查了一下它：
...$ systemctl start screenControl
...$ systemctl status screenControl
● screenControl.service - Screen control service
Loaded: loaded (/etc/systemd/system/screenControl.service; disabled; vendor preset: enabled)
Active: active (running) since Sun 2015-12-13 22:31:54 GMT; 6s ago
Main PID: 19871 (screenControl)
CGroup: /system.slice/screenControl.service
└─19871 /usr/bin/screenControl
Dec 13 22:31:54 User systemd[1]: Started Screen control service.
Dec 13 22:31:54 User screenControl[19871]: Launching server
Dec 13 22:31:54 User screenControl[19871]: Listening...
因此它正在运行，但是当我现在在Web应用程序中选择关闭屏幕时，什么也没发生...我再次检查了服务状态，它收到了关闭屏幕的消息，但是命令退出并出现错误：
...
Dec 13 22:31:54 User screenControlTest[19871]: Launching server
Dec 13 22:31:54 User screenControlTest[19871]: Listening...
Dec 13 22:32:25 User screenControlTest[19871]: New connection
Dec 13 22:32:25 User screenControlTest[19871]: Message Received: "screensOff"
Dec 13 22:32:25 User screenControlTest[19871]: Turning off screens...
Dec 13 22:32:25 User screenControlTest[19871]: exit status 1
Dec 13 22:32:25 User screenControlTest[19871]: Connection closed
这是什么问题，如何使该命令作为服务工作？ 一旦运行正常，我想在机器开机时自动启动服务，尽管使用systemd我认为这很简单:
...$ systemctl enable screenControl
xset: unable to open display ""
