深海游弋的鱼 – 第 103 页 – 智障儿童欢乐多

Ubuntu 17.10使用minicom通过USB串口线连接开发板(解决不能输入的问题）

Ubuntu 17.10上比较好用的串口终端是minicom，下面我们介绍一下使用方法。

继续阅读Ubuntu 17.10使用minicom通过USB串口线连接开发板(解决不能输入的问题）

OpenMediaVault-4.0.15执行更新(apt update)时报错“TypeError: 'NoneType' object is not callable”

OpenMediaVault-4.0.15执行更新(apt update)时报错,详细错误信息如下：

命中:12 http://packages.openmediavault.org/public arrakis InRelease

Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at 0x7f7dc337b730>

Traceback (most recent call last):

File "/usr/lib/python3.5/weakref.py", line 117, in remove

TypeError: 'NoneType' object is not callable

Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at 0x7f7dc337b730>

Traceback (most recent call last):

File "/usr/lib/python3.5/weakref.py", line 117, in remove

TypeError: 'NoneType' object is not callable

通过观察发现，只要从packages.openmediavault.org中下载文件失败，就会报告这个错误。

发生错误之后，重新执行

1	$ sudo apt update

即可解决这个问题，或者忽略这个错误信息即可。

Python中用Ctrl+C终止threading初始化的多线程脚本

在编写Python脚本的时候，难免会遇到使用多线程操作的情况。

正常情况下，我们都习惯在Shell中使用Ctrl+C终止脚本的执行，但是在多线程环境中，我们发现Ctrl+C并不能有效终止开启了多线程的脚本。

由于Python提供的threading模块并没有提供线程的退出接口，导致我们没有办法终止已经正常运行的线程，尤其是线程被阻塞在内核的情况下。

解决这个问题的办法就是在线程初始化之后设置为守护模式（setDaemon），并且不要调用join阻塞主线程。这样当主线程退出的时候，其他线程也随之退出了。

下面是我们解决这种问题的一个例子：

#!/bin/env python

# -*- coding: utf-8 -*-

import threading

import signal

import sys

import time

global is_exit

is_exit = False

def doWork(i):

print "thread[%d] enter\n"%(i)

while not is_exit:

time.sleep(0.2)

print "thread[%d] terminated\n"%(i)

def sig_handler(signum, frame):

is_exit = True

sys.exit(0)

if __name__ == "__main__":

signal.signal(signal.SIGINT, sig_handler)

signal.signal(signal.SIGTERM, sig_handler)

cc = 5

for i in range(cc):

t = threading.Thread(target=doWork, args=(i,))

t.setDaemon(True)

t.start()

raw_input("Waiting For Ctrl+C\n")

参考链接

Python 中用 Ctrl+C 终止多线程程序的问题解决

ubuntu 14.04/ubuntu 17.10做主机双网卡共享上网(NAT)

需求是电脑通过无线上网，然后把有线共享给其他设备，其他设备通过电脑代理上网。

电脑上有两张网卡，一张有线网卡，名字为eth0,一张无线网卡，名字为wlan0。

电脑的有线网卡配置的静态IP地址为：192.168.0.1。

对于Ubuntu 16.10/17.10系统，请参考 Ubuntu 16.10/17.10无法通过/etc/rc.local开机启动应用激活系统对于/etc/rc.local功能的支持。

电脑上执行如下命令：

$ echo "1" | sudo tee /proc/sys/net/ipv4/ip_forward

$ sudo iptables -F

$ sudo iptables -P INPUT ACCEPT

$ sudo iptables -P FORWARD ACCEPT

#打开NAT,无线网卡这里大eth0改wlan0

$ sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

#保存设置信息，下次开机自动开启代理

$ sudo sed -i '$a\net.ipv4.ip_forward = 1' /etc/sysctl.conf

$ sudo sed -i '$a\iptables -F' /etc/rc.local

$ sudo sed -i '$a\iptables -P INPUT ACCEPT' /etc/rc.local

$ sudo sed -i '$a\iptables -P FORWARD ACCEPT' /etc/rc.local

$ sudo sed -i '$a\iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE' /etc/rc.local

此时，由于我们没有开启DHCP功能，因此只能设置静态IP地址。客户机设置如下：
eth0:192.168.0.10 掩码：255.255.255.0 网关：192.168.0.1

参考链接

ubuntu做主机双网卡共享上网方法

Python简单实现WebSocket

实现一个简单的聊天室程序，代码如下：

#-*- coding:utf8 -*-

import threading
import hashlib
import socket
import base64

global clients
clients = {}

#通知客户端
def notify(message):
    for connection in clients.values():
        connection.send('%c%c%s' % (0x81, len(message), message))

#客户端处理线程
class websocket_thread(threading.Thread):
    def __init__(self, connection, username):
        super(websocket_thread, self).__init__()
        self.connection = connection
        self.username = username
    
    def run(self):
        print 'new websocket client joined!'
        data = self.connection.recv(1024)
        headers = self.parse_headers(data)
        token = self.generate_token(headers['Sec-WebSocket-Key'])
        self.connection.send('\
HTTP/1.1 101 WebSocket Protocol Hybi-10\r\n\
Upgrade: WebSocket\r\n\
Connection: Upgrade\r\n\
Sec-WebSocket-Accept: %s\r\n\r\n' % token)
        while True:
            try:
                data = self.connection.recv(1024)
            except socket.error, e:
                print "unexpected error: ", e
                clients.pop(self.username)
                break
            data = self.parse_data(data)
            if len(data) == 0:
                continue
            message = self.username + ": " + data
            notify(message)
            
    def parse_data(self, msg):
        v = ord(msg[1]) & 0x7f
        if v == 0x7e:
            p = 4
        elif v == 0x7f:
            p = 10
        else:
            p = 2
        mask = msg[p:p+4]
        data = msg[p+4:]
        return ''.join([chr(ord(v) ^ ord(mask[k%4])) for k, v in enumerate(data)])
        
    def parse_headers(self, msg):
        headers = {}
        header, data = msg.split('\r\n\r\n', 1)
        for line in header.split('\r\n')[1:]:
            key, value = line.split(': ', 1)
            headers[key] = value
        headers['data'] = data
        return headers

def generate_token(self, msg):
        key = msg + '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
        ser_key = hashlib.sha1(key).digest()
        return base64.b64encode(ser_key)

#服务端
class websocket_server(threading.Thread):
    def __init__(self, port):
        super(websocket_server, self).__init__()
        self.port = port

def run(self):
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        sock.bind(('127.0.0.1', self.port))
        sock.listen(5)
        print 'websocket server started!'
        while True:
            connection, address = sock.accept()
            try:
                username = "ID" + str(address[1])
                thread = websocket_thread(connection, username)
                thread.start()
                clients[username] = connection
            except socket.timeout:
                print 'websocket connection timeout!'

if __name__ == '__main__':
    server = websocket_server(9000)
    server.start()

#-*- coding:utf8 -*-

import threading

import hashlib

import socket

import base64

global clients

clients = {}

#通知客户端

def notify(message):

for connection in clients.values():

connection.send('%c%c%s' % (0x81, len(message), message))

#客户端处理线程

class websocket_thread(threading.Thread):

def __init__(self, connection, username):

super(websocket_thread, self).__init__()

self.connection = connection

self.username = username

def run(self):

print 'new websocket client joined!'

data = self.connection.recv(1024)

headers = self.parse_headers(data)

token = self.generate_token(headers['Sec-WebSocket-Key'])

self.connection.send('\

HTTP/1.1 101 WebSocket Protocol Hybi-10\r\n\

Upgrade: WebSocket\r\n\

Connection: Upgrade\r\n\

Sec-WebSocket-Accept: %s\r\n\r\n' % token)

while True:

try:

data = self.connection.recv(1024)

except socket.error, e:

print "unexpected error: ", e

clients.pop(self.username)

break

data = self.parse_data(data)

if len(data) == 0:

continue

message = self.username + ": " + data

notify(message)

def parse_data(self, msg):

v = ord(msg[1]) & 0x7f

if v == 0x7e:

p = 4

elif v == 0x7f:

p = 10

else:

p = 2

mask = msg[p:p+4]

data = msg[p+4:]

return ''.join([chr(ord(v) ^ ord(mask[k%4])) for k, v in enumerate(data)])

def parse_headers(self, msg):

headers = {}

header, data = msg.split('\r\n\r\n', 1)

for line in header.split('\r\n')[1:]:

key, value = line.split(': ', 1)

headers[key] = value

headers['data'] = data

return headers

def generate_token(self, msg):

key = msg + '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'

ser_key = hashlib.sha1(key).digest()

return base64.b64encode(ser_key)

#服务端

class websocket_server(threading.Thread):

def __init__(self, port):

super(websocket_server, self).__init__()

self.port = port

def run(self):

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

sock.bind(('127.0.0.1', self.port))

sock.listen(5)

print 'websocket server started!'

while True:

connection, address = sock.accept()

try:

username = "ID" + str(address[1])

thread = websocket_thread(connection, username)

thread.start()

clients[username] = connection

except socket.timeout:

print 'websocket connection timeout!'

if __name__ == '__main__':

server = websocket_server(9000)

server.start()

测试页面：

<!DOCTYPE html>
</html>
    <head>
        <meta charset="utf-8">
    </head>
    <body>
        <h3>WebSocketTest</h3>
        <div id="login">
            <div>
                <input id="serverIP" type="text" placeholder="服务器IP" value="127.0.0.1" autofocus="autofocus" />
                <input id="serverPort" type="text" placeholder="服务器端口" value="9000" />
                <input id="btnConnect" type="button" value="连接" onclick="connect()" />
            </div>
            <div>
                <input id="sendText" type="text" placeholder="发送文本" value="I'm WebSocket Client!" />
                <input id="btnSend" type="button" value="发送" onclick="send()" />
            </div>
            <div>
                <div>
                    来自服务端的消息
                </div>
                <textarea id="txtContent" cols="50" rows="10" readonly="readonly"></textarea>
            </div>
        </div>
    </body>
    <script>
        var socket;

function connect() {
            var host = "ws://" + $("serverIP").value + ":" + $("serverPort").value + "/"
            socket = new WebSocket(host);
            try {

socket.onopen = function (msg) {
                    $("btnConnect").disabled = true;
                    alert("连接成功！");
                };

socket.onmessage = function (msg) {
                    if (typeof msg.data == "string") {
                        displayContent(msg.data);
                    }
                    else {
                        alert("非文本消息");
                    }
                };

socket.onclose = function (msg) { alert("socket closed!") };
            }
            catch (ex) {
                log(ex);
            }
        }

function send() {
            var msg = $("sendText").value
            socket.send(msg);
        }

window.onbeforeunload = function () {
            try {
                socket.close();
                socket = null;
            }
            catch (ex) {
            }
        };

function $(id) { return document.getElementById(id); }

Date.prototype.Format = function (fmt) { //author: meizz 
            var o = {
                "M+": this.getMonth() + 1, //月份 
                "d+": this.getDate(), //日 
                "h+": this.getHours(), //小时 
                "m+": this.getMinutes(), //分 
                "s+": this.getSeconds(), //秒 
                "q+": Math.floor((this.getMonth() + 3) / 3), //季度 
                "S": this.getMilliseconds() //毫秒 
            };
            if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
            for (var k in o)
                if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
            return fmt;
        }

function displayContent(msg) {
            $("txtContent").value += "\r\n" +new Date().Format("yyyy/MM/dd hh:mm:ss")+ ":  " + msg;
        }
        function onkey(event) { if (event.keyCode == 13) { send(); } }
    </script>
</html>

<!--

@http://www.cnblogs.com/zhuweisky/p/3930780.html

-->

<!DOCTYPE html>

</html>

<head>

</head>

<body>

<h3>WebSocketTest</h3>

<div>

</div>

<div>

</div>

<div>

来自服务端的消息

</div>

</div>

</body>

var socket;

function connect() {

var host = "ws://" + $("serverIP").value + ":" + $("serverPort").value + "/"

socket = new WebSocket(host);

try {

socket.onopen = function (msg) {

$("btnConnect").disabled = true;

alert("连接成功！");

};

socket.onmessage = function (msg) {

if (typeof msg.data == "string") {

displayContent(msg.data);

}

else {

alert("非文本消息");

}

};

socket.onclose = function (msg) { alert("socket closed!") };

}

catch (ex) {

log(ex);

}

function send() {

var msg = $("sendText").value

socket.send(msg);

}

window.onbeforeunload = function () {

try {

socket.close();

socket = null;

}

catch (ex) {

}

};

function $(id) { return document.getElementById(id); }

Date.prototype.Format = function (fmt) { //author: meizz

var o = {

"M+": this.getMonth() + 1, //月份

"d+": this.getDate(), //日

"h+": this.getHours(), //小时

"m+": this.getMinutes(), //分

"s+": this.getSeconds(), //秒

"q+": Math.floor((this.getMonth() + 3) / 3), //季度

"S": this.getMilliseconds() //毫秒

};

if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));

for (var k in o)

if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));

return fmt;

}

function displayContent(msg) {

$("txtContent").value += "\r\n" +new Date().Format("yyyy/MM/dd hh:mm:ss")+ ": " + msg;

}

function onkey(event) { if (event.keyCode == 13) { send(); } }

</script>

</html>

参考链接

python简单实现websocket

原生JS写Ajax的请求函数

一般我们写网页的时候，如果用到Ajax请求服务器，都是使用JQuery等已经封装好的库来调用，比较简单。

但是一般这些库的功能很多，引入了太多我们用不到的东西，如果我们需要写一个功能单一，简单的页面，完全用不到引用如此庞大的库文件。

我们可以简单实现一个自己的Ajax请求功能，具体的代码如下：

var ajax = {};
ajax.x = function () {
	if (typeof XMLHttpRequest !== 'undefined') {
		return new XMLHttpRequest();
	}
	var versions = [
	"MSXML2.XmlHttp.6.0",
	"MSXML2.XmlHttp.5.0",
	"MSXML2.XmlHttp.4.0",
	"MSXML2.XmlHttp.3.0",
	"MSXML2.XmlHttp.2.0",
	"Microsoft.XmlHttp"
	];

var xhr;
	for (var i = 0; i < versions.length; i++) {
		try {
			xhr = new ActiveXObject(versions[i]);
			break;
		} catch (e) {
		}
	}
	return xhr;
};

ajax.send = function (url, method, data, success,fail,async) {
	if (async === undefined) {
		async = true;
	}
	var x = ajax.x();
	x.open(method, url, async);
	x.onreadystatechange = function () {
		if (x.readyState == 4) {
			var status = x.status;
			if (status >= 200 && status < 300) {
				success && success(x.responseText,x.responseXML)
			} else {
				fail && fail(status);
			}
			
		}
	};
	if (method == 'POST') {
		x.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
	}
	x.send(data)
};

ajax.get = function (url, data, callback, fail, async) {
	var query = [];
	for (var key in data) {
		query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));
	}
	ajax.send(url + (query.length ? '?' + query.join('&') : ''), 'GET', null, callback, fail, async)
};

ajax.post = function (url, data, callback, fail, async) {
	var query = [];
	for (var key in data) {
		query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));
	}
	ajax.send(url,'POST', query.join('&'), callback, fail, async)
};

var ajax = {};

ajax.x = function () {

if (typeof XMLHttpRequest !== 'undefined') {

return new XMLHttpRequest();

}

var versions = [

"MSXML2.XmlHttp.6.0",

"MSXML2.XmlHttp.5.0",

"MSXML2.XmlHttp.4.0",

"MSXML2.XmlHttp.3.0",

"MSXML2.XmlHttp.2.0",

"Microsoft.XmlHttp"

];

var xhr;

for (var i = 0; i < versions.length; i++) {

try {

xhr = new ActiveXObject(versions[i]);

break;

} catch (e) {

}

return xhr;

};

ajax.send = function (url, method, data, success,fail,async) {

if (async === undefined) {

async = true;

}

var x = ajax.x();

x.open(method, url, async);

x.onreadystatechange = function () {

if (x.readyState == 4) {

var status = x.status;

if (status >= 200 && status < 300) {

success && success(x.responseText,x.responseXML)

} else {

fail && fail(status);

}

};

if (method == 'POST') {

x.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');

}

x.send(data)

};

ajax.get = function (url, data, callback, fail, async) {

var query = [];

for (var key in data) {

query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));

}

ajax.send(url + (query.length ? '?' + query.join('&') : ''), 'GET', null, callback, fail, async)

};

ajax.post = function (url, data, callback, fail, async) {

var query = [];

for (var key in data) {

query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));

}

ajax.send(url,'POST', query.join('&'), callback, fail, async)

};

使用方法：GET

ajax.get('/test.php', {foo: 'bar'}, function(response,xml) {

//success

function(status){

//fail

});

POST

ajax.post('/test.php', {foo: 'bar'}, function(response,xml) {

//succcess

},function(status){

//fail

});

这里需要注意一个问题，如果我们想要发送类似

1	http://www.mobibrw.com/control?op_code=code&op_cmd=cmd

的URL，是不能通过上面的发送方式（字段填写在data参数中）发送的，上面的发送方式是属于表单的上传方式。

我们需要用下面的方式进行处理（自己拼凑URL）

var sendCmd = "?op_code=" + code + "&op_cmd=" + cmd;

ajax.post('/control' + sendCmd,'',function(response,xml) {

console.log('success');

function(status){

console.log('failed:' + status);

});

参考链接

树莓派2 B+任务栏(LXPanel)不断闪烁消失(RASPBIAN STRETCH WITH DESKTOP)

长时间不用的一个树莓派2 B+，使用的系统为RASPBIAN STRETCH WITH DESKTOP。在重新加电后，任务栏(LXPanel)不断闪烁消失，貌似启动的时候发生了异常，然后崩溃，重启，循环往复（并不是一直消失不见，而是不断闪烁）。但是查看系统日志，却找不到相关的异常日志。

这种现象，可以通过如下方法解决：

$ sudo apt-get remove --purge lxpanel

$ sudo apt-get install lxpanel

$ sudo apt-get autoremove

$ rm -rf ~/.config/lxpanel/LXDE-pi

$ sudo reboot

参考链接

树莓派3 B+下次启动强制检查系统分区

树莓派使用的过程中，难免会由于突然断电等原因导致SD卡发生错误。这个时候我们就需要强制让树莓派在下次启动的时候进行磁盘检查。

如果是普通分区，可以卸载后执行fsck命令，但是如果是系统分区，由于一直被占用，因此是没有办法进行磁盘检查的。

网上找了一下，找到了解决办法，可以强制让树莓派在下次系统启动的时候，强制检查系统分区。具体的方式如下：

$ sudo touch /forcefsck

$ sudo reboot

参考链接

Checking sdcard for errors, unmount problem

树莓派3 B+设置静态IP

最近需要为一台树莓派3 B+设置静态IP地址，结果尝试了半天总是不成功。

网上搜索了一下，找到解决方法。

修改/etc/dhcpcd.conf文件

1	$ sudo vim /etc/dhcpcd.conf

在文件的尾部增加如下内容：

interface eth0

static ip_address=192.168.0.10/24

static routers=192.168.0.1

static domain_name_servers=192.168.0.1

interface wlan0

static ip_address=192.168.0.200/24

static routers=192.168.0.1

static domain_name_servers=192.168.0.1

上面的配置文件中,eth0是有线的配置, wlan0是无线配置
ip_address就是静态IP, 后面要接/24
routers是网关
domain_name_servers是DNS

参考链接

设置树莓派3 B+的静态IP

树莓派3 UART及GPIO针脚定义

树莓派GPIO接口只能输入输出数字信号（0&1等），传感器等模拟信号，需要通过ADC（模数转换器）进行转化。

树莓派3的GPIO管脚定义与前代有所差别了，具体的管脚参照下图：

继续阅读树莓派3 UART及GPIO针脚定义

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