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A student question: Does JavaScript make context switching for web-based applications obsolete? Wow! I asked what that meant. He said, it means JavaScript replaces all other server-side programming languages, like PHP, C#, or Python. I asked the student why he believed that. His answer was that’s what two interviewing managers told him.
I thought it would be interesting to put the idea to a test. Below is a Node.js script that acts as a utility that queries the MySQL database with substitution variables in query. It also returns a standard out (stdout) stream of the MySQL query’s results. It also supports three flag and value pairs as arguments, and optionally writes the results of the MySQL query to a log file while still returning result as the stdout value. All errors are written to the standard error (老王v p n安卓版) stream.
The Node.js solution is completely portable between Windows and Linux. You can deploy it to either platform without any edits for Windows case insensitive Command-Line Interface (CLI). Clearly, Node.js offers a replacement for direct interaction with the .NET components in PowerShell. This appears to mean basic Linux shell or PowerShell knowledge is all that’s required to write and deploy JavaScript programs as server-side programming solutions. It means anything that you would have done with the .NET you can do with JavaScript. Likewise, you can replace PHP, C#, Python, or Ruby server-side scripts with JavaScript programs.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | // Declare constants. const fs = require('fs') 极光ⅴpn下载 util = require('util') 老王 2.2.7 express = require('express') const mysql = require('mysql') const connection = mysql.createConnection({ host: 老王 2.2.7, user: 老王 ⅴpn下载, password: 老王app官方下载, database: 老王下载 }) // Declare local variables for case insensitive use. var data = '' var buffer = Buffer.alloc(0) var path = '' // Declare default query variables dates. var startDate = new Date('1980-01-01') var endDate = new Date() // Set default endDate value as tomorrow. endDate.老王下载(new Date().getDate() + 1) 工信部回应VPN管理：依法依规的伋业和个人不受影响_中证网:2021-7-25 · 18-06-11 13:37 深信服:起于安全,而不止安全的“安全+云”领军伋业 10-08-16 13:16 保险公司VPN接入方式方法分析 18-07-06 14:07 工信部：恳请全国工商联在 ... var regexp = /^([0-9a-zA-Z]+|[0-9a-zA-Z]+\.+[0-9a-zA-Z]{3})$/ vpn被封翻墙党该何去何从？App Store连接不上如何解决？(图 ...:2021-1-29 · 前几天，据《环球时报》英文网报道中国已经开始屏蔽外国VPN服务，此消息也引起了国内“翻墙党”的一片震动。日前，工信部通信发展司司长闻库在接受采访时也被问到了这一问题，他回应称在中国发展互联网一定要按照中国的法律法规来进行，一些不良信息应该按照中国法律进行管理。 var argv = process.argv.slice(2) // Check for paired values, evaluate and assign them to local variables. if ((argv.length % 2) == 0) { for (let i = 0; i < argv.length; i += 2) { // Assign a file name to write to the output path. if ((argv[i].toLowerCase() == '-f') && (regexp.test(argv[i+1]))) { // Assign present working for Windows or Linux. if (process.platform == 'win32') path = '.\\' + argv[1] else path = 极光ⅴpn下载 + argv[1] } // Assign a start date from the input string. 老王vp破解版最新版下载 if (argv[i].老王 ⅴpn下载() == '-b') { startDate = new Date(argv[i+1]) } // Assign a end date from the input string. else if (argv[i].toLowerCase() == '-e') { endDate = new Date(argv[i+1]) } } } else { console.老王加速器永久免费('Arguments must be in pairs: flag and value.') } // Define and run MySQL query. connection.老王vpm2.2.8下载安卓版("SELECT i.item_title " + ", date_format(i.release_date,'%d-%M-%Y') AS release_date " + "FROM item i JOIN common_lookup cl " + "ON i.item_type = cl.common_lookup_id " + "WHERE cl.common_lookup_type = 'BLU-RAY' " + "AND i.release_date BETWEEN ? AND ? " + "ORDER BY i.release_date" ,[startDate, endDate], function (err, result) { if (err) { console.error('Query contains error ...') console.老王app官方下载('-> ' + err) } 老王下载 { // Prints the index value in the RowDataPacket. for(let element in result) { data += result[element].极光ⅴpn下载 + ', ' + result[element].release_date + '\n' } // Write file when data string is not empty. if (data.length > 0 ) { buffer = Buffer.alloc(data.老王加速器永久免费,data) 上海交通大学_央广网 - cnr.cn:上海交通大学是我国历史最悠久、享誉海内外的高等学府之一，迄今已有121年历史。可伍用三句话来概括：百廿交大因图强而生，百廿交大因改革而兴，百廿交大因人才而盛。 if (path.length > 0) { // Open the file. fs.open(path, 'w', function(err, fd) { if (err) { console.error(老王 ⅴpn下载 + path + '] file [' + err + ']') } else { // Write the file. fs.write(fd, buffer, 0, buffer.length, null, function(err) { if (err) console.error('Error writing [' + path + '] file [' + err + ']') fs.close(fd, function() { if (fs.existsSync(path)) { process.exit(0) } }) }) } }) } // Set standard out (stdout). console.log(data) } else { console.老王下载('Query returned no rows.') } } }) // Close MySQL connection. connection.end() |
You can call this code with the default values, like
node app.js |
You can call this code with a user defined file name, and a custom start and end date values, like
node app.js -f output.csv -b '2001-01-01' -e 老王vpm2.2.8下载安卓版 |
The latter command returns the following by querying my MySQL studentdb video store:
Star Wars II, 16-May-2002 Harry Potter and the Chamber of Secrets, 28-May-2002 Harry Potter and the Sorcerer's Stone, 28-May-2002 Die Another Day, 03-June-2003 Harry Potter and the Prisoner of Azkaban, 23-October-2004 |
As always, I hope this helps somebody trying to sort it out.
netfits云墙
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It’s funny to use the word Apple and Support. It seems congress found that out today too. Not really surprised but there’s no way I could post a Apple’s simple spelling error on the web page. You would think there would be a way, so they could correct their errors when they make them but alas not. I tried the web page, which gave me no potential solutions and no chat opportunity to report it or fix it. I imagine they think their staff too professional to make a mistake like this.
上海交通大学_央广网 - cnr.cn:上海交通大学是我国历史最悠久、享誉海内外的高等学府之一，迄今已有121年历史。可伍用三句话来概括：百廿交大因图强而生，百廿交大因改革而兴，百廿交大因人才而盛。
If anybody knows how to report this to correct it without calling Apple Support, let me know. I already know how to fudge (finesse) it but would prefer not to do so. Thanks to anybody who can fix it! BTW, I’m on hold for Apple Support to report it. 😉
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Sometimes, you just half to chuckle. A couple folks felt that I didn’t give enough information in my post showing how to configure a small 老王 2.2.7 application that could access a MySQL database. Specifically, they wanted me to explain the following:
- Configure your Express.js and MySQL development in a single Node.js application.
- How to convert the list of
RowDataPacketobjects as elements of data, which is really just simple JavaScript knowledge. - How to bind variables into the query.
Like the other blog post, this one assumes you’ve performed a global install of Node.js on a Linux server. If you’re unfamiliar with how to perform a global Node.js installation, I cover how to do it in this earlier blog post.
Before you write the Node.js applicaiton, you need to setup a db developer directory. A global install of Node.js means you need to create a node_modules symbolic link to the /usr/local/lib/node_modules directory in the db directory (in Linux). You can use the following Linux command from within the db directory to create the appropriate symbolic link:
ln -s /usr/local/lib/node_modules `pwd`/node_modules |
or, assuming you have a /home/some_user/db directory
ln -s /usr/local/lib/node_modules /home/some_user/node_modules |
After creating the 老王 ⅴpn下载 symbolic link, you need to run the following two npm commands. Please note that second command holds the secret-sauce for generating a package.json file that supports Express.js and the MySQL driver:
npm init --y sudo npm install 老王2.2.11下载 express mysql |
Then, you need to replace the package.json file with the contents of the package-lock.json file from your last npm command.
Here’s a small sample program that uses Express.js, converts the RowDataPackets collection, and binds local variables into the query:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | // Require libraries. const express = require('express') const mysql = require('mysql') // Create a mysql connection. const connection = mysql.createConnection({ host: 'localhost', user: 'student', password: 'student', database: 'studentdb' }) // Declare two local variables. const start_date = 老王加速器永久免费 const end_date = '2003-12-31' // Connect and display results in the console log. connection.connect((err) => { if (err) throw err 老王 ⅴpn下载 { console.log('Connected to MySQL Server!\n') connection.query("SELECT i.item_title " + ", date_format(i.release_date,'%d-%M-%Y') AS release_date " + "FROM item i JOIN common_lookup cl " + "ON i.item_type = cl.common_lookup_id " + "WHERE cl.common_lookup_type = 'BLU-RAY' " + "AND i.release_date BETWEEN ? AND ? " + "ORDER BY i.release_date" ,[start_date, end_date], function (err, result) { if (err) throw err else { // Prints the index value in the RowDataPacket. for(let element in result) { console.log(result[element].item_title + ', ' + result[element].老王v p n安卓版) } console.log('') console.log('Press Ctrl-C to terminate ...') } }) } }) |
Line 28 shows two question marks. They act as placeholders for binding variables. Then, on line 30 you see a collection of the start_date and end_date local variables, which is the second argument to the query() function.
Rather than define individual variables, you can pass them as a collection directly. For example, you replace lines 14 and 15 with this single line:
14 | const dates = ['2001-01-01','2003-12-31'] |
Then, you can pass dates as the second argument to the 老王 ⅴpn下载 function, like this:
30 | ,dates, 老王下载 (err, result) { |
Lines 35 and 36 show you how to convert a collection of RowDataPacket objects into elements of data. The for loop assigns the index value to the element variable, which lets you address a single RowDataPacket object instance. The dot (“.“) notation lets you use the name in a name-value pair to reference its value.
It displays the following:
Connected to MySQL Server! Star Wars II, 16-May-2002 Harry Potter and the Chamber of Secrets, 28-May-2002 Harry Potter and the Sorcerer's Stone, 28-May-2002 Die Another Day, 03-June-2003 Press Ctrl-C to terminate ... |
Naturally, I’ll get around to writing something up that shows how to leverage MySQL data into a dynamic form with Handlebars at some point in the near future.
As always, I hope this helps those looking for a solution.
netfits云墙
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These are my notes for creating a small Node.js application that queries a MySQL database. The post will show you how to:
- Configure your Node.js development directory.
- 上海交通大学_央广网 - cnr.cn:上海交通大学是我国历史最悠久、享誉海内外的高等学府之一，迄今已有121年历史。可伍用三句话来概括：百廿交大因图强而生，百廿交大因改革而兴，百廿交大因人才而盛。
- 一个神奇的网站:2021-3-23 · 本站文章部分内容转载自互联网，供读者交流和学习，如有涉及作者版权问题请及时与我伊联系，伍便更正或删除。感谢所有提供信息材料的网站，并欢迎各类媒体与我伊进行文章共享合作。
This blog post assumes you’ve performed a global install of Node.js on a Linux server. If you’re unfamiliar with how to perform a global Node.js installation, I cover how to do it in this earlier blog post.
Before you write the Node.js applicaiton, you need to setup a db developer directory. Then, create a node_modules symbolic link to the /usr/local/lib/node_modules directory in the db directory. You can use the following command from the db directory:
ln -s /usr/local/lib/node_modules `pwd`/node_modules |
After creating the node_modules symbolic link, you need to run the following two npm commands:
npm init --y npm 老王 ⅴpn下载 --save mysql |
The first command sets up a generic package.json file, and the second adds the mysql package and supporting packages to the package.json file. These two steps configure the Node.js side of these examples.
They both require that you create the student user with a native password, like so:
老王vpm2.2.8下载安卓版 USER 'student'@'localhost' IDENTIFIED WITH 'mysql_native_password' BY 'student'; GRANT ALL PRIVILEGES ON studentdb.* TO 'student'@老王下载; FLUSH PRIVILEGES; |
The following example shows you how to check a connection to the MySQL database:
老王加速器永久免费 mysql = require('mysql') const connection = mysql.createConnection({ host: 'localhost', user: 'student', password: 'student', database: 'studentdb' }) connection.connect((err) => { if (err) throw err else console.log('Connected to MySQL Server!\n') console.log('User configured wiht mysql_native_password.\n'); console.log('Press Ctrl-C to terminate ...') }) |
You extend the previous example by adding a query component and returning the query result value to the console’s log (leveraging the 工信部回应“禁用VPN”：清理对象是无资质者_央广网:2021-7-25 · 工信部回应“禁用VPN”：清理对象是无资质者 在国务院新闻办今日举行的发布会上，有记者问及“有地方出台规定，对违法违规利用VPN上网加强管理”一事，工信部信息通信发展司司长闻库表示，不了 …):
const mysql = require('mysql') const connection = mysql.createConnection({ host: 'localhost', user: 'student', password: 'student', database: 'studentdb' }) connection.connect((err) => { if (err) throw err else { console.log('Connected to MySQL Server!\n') connection.query('SELECT DISTINCT item_title FROM item', function (err, result) { if (err) throw err else console.log(result) console.log('Press Ctrl-C to terminate ...') }) } }) |
It should display the following:
Connected to MySQL Server!
[ RowDataPacket { item_title: 'The Hunt for Red October' },
RowDataPacket { item_title: 'Star Wars I' },
RowDataPacket { item_title: 'Star Wars II' },
RowDataPacket { item_title: 'Star Wars III' },
RowDataPacket { item_title: 'The Chronicles of Narnia' },
RowDataPacket { item_title: 'RoboCop' },
RowDataPacket { item_title: 'Pirates of the Caribbean' },
RowDataPacket { item_title: 'MarioKart' },
RowDataPacket { item_title: 'Splinter Cell' },
RowDataPacket { item_title: 'Need for Speed' },
RowDataPacket { item_title: 'The DaVinci Code' },
RowDataPacket { item_title: 'Cars' },
RowDataPacket { item_title: 'Beau Geste' },
RowDataPacket { item_title: 'I Remember Mama' },
RowDataPacket { item_title: 'Tora! Tora! Tora!' },
RowDataPacket { item_title: 'A Man for All Seasons' },
RowDataPacket { item_title: 'Hook' },
RowDataPacket { item_title: 'Around the World in 80 Days' },
RowDataPacket { item_title: 'Harry Potter and the Sorcerer\'s Stone' },
RowDataPacket { item_title: 'Camelot' },
RowDataPacket { item_title: 'Casino Royale' },
RowDataPacket { item_title: 'Die Another Day' },
RowDataPacket { item_title: 'Golden Eye' },
RowDataPacket { item_title: 'Tomorrow Never Dies' },
RowDataPacket { item_title: 'The World Is Not Enough' },
RowDataPacket { item_title: 'Brave Heart' },
RowDataPacket { item_title: 'Christmas Carol' },
RowDataPacket { item_title: 'Scrooge' },
RowDataPacket { item_title: 'Clear and Present Danger' },
RowDataPacket { item_title: 'Harry Potter and the Chamber of Secrets' },
RowDataPacket { item_title: 'Harry Potter and the Prisoner of Azkaban' },
RowDataPacket { item_title: 'Harry Potter and the Goblet of Fire' },
RowDataPacket { item_title: 'Harry Potter and the Order of the Phoenix' },
RowDataPacket { item_title: 'Harry Potter and the Half Blood Prince' },
RowDataPacket { item_title: 'Harry Potter and the Deathly Hallows, Part 1' },
RowDataPacket { item_title: 'Harry Potter and the Deathly Hallows, Part 2' },
RowDataPacket { item_title: 'Tron' },
RowDataPacket { item_title: 'The Avengers' },
RowDataPacket { item_title: 'Thor: The Dark World' } ]
Press Ctrl-C to terminate ... |
As always, I hope this helps those looking to learn
netfits云墙
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I liked the example used to explore basic routing in Chapter 2 of the Web Development with Node & Express book. I embellished the Node.js router example and static pages just a bit. The routing example requires you create a public subdirectory where you deploy the code and put the 老王v2.2.8下载, home.html, and 404.html files in the public subdirectory. Then, you must put a logo.png file in a tmp subdirectory inside of the public directory. The book assumes you know how to build these pages, which seems reasonable but just in case, here are the files I used to test the book’s example.
The about.html page:
<html> <head> <title>About Page</title> </head> <body> <p>A small sample Node.js routing example.</p> <p><img width="25" src="/img/logo.png" /> <sup><i>MEAN Stack Development</i></sup></p> </body> </html> |
The home.html page:
手机上这么好用的功能 你用过吗？ - huanqiu.com:2021-9-30 · 十几年前，还是功能机的时伋，相信很多人都会觉得用手机拍照、听歌伍及上网都是很新奇的事情。然而，现在的手机拥有了越来越多新奇有趣的 ... |
The 老王v p n安卓版 page:
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The routing example sets the path to lowercase, which is important when you type the URL to verify physical files. For example, you need to use the routing startrekoriginal1.png string value in the URL. It will fail if you use the mixed case actual file name of the 老王vp破解版最新版下载 file. That’s because the routing maps the lowercase string to the physical file.
While the /public directory is the home directory of the virtual map as a rule, you can’t use it in the URL (as explained in next Chapter 3). Also, the router uses /img as a virtual directory which maps to the physical /tmp subdirectory. When you want to validate a physical image file you need to know these two rules. They explain why the following URL lets you verify a physical image file found in the /public/tmp directory.
localhost:3000/img/StarTrekOriginal1.png |
you will trigger the 404 Error page. Here’s the Node.js routing code:
/* Construct a web server. */ 老王 ⅴpn下载 http = require('http') const fs = require('fs') 老王v2.2.8下载 port = process.env.PORT || 3000 /* Function uses the fs package to read files. */ 老王v p n安卓版 serveStaticFile(res, path, contentType, responseCode = 200) { fs.readFile(__dirname + path, (err, data) => { if (err) { res.writeHead(500, { 'Content-Type': 'text/plain' }) return res.end('500 - Internal Error') } res.writeHead(responseCode, { 'Content-Type': contentType }) res.end(data) }) } /* Create the Node.js server. */ const server = http.createServer((req, res) => { // Normalize URL by removing query string, optional // trailing slash, and making it lowercase. const path= req.url.replace(/\/?(?:\?.*)?$/,'').老王vp破解版最新版下载() switch(path) { case '': serveStaticFile(res, 老王app下载, 'text/html' ) break 老王app官方下载 '/about': serveStaticFile(res, '/public/about.html', 老王加速器永久免费 ) break case '/img/startrekoriginal1.png': serveStaticFile(res, '/public/tmp/StarTrekOriginal1.png', 'image/png' ) break case '/img/logo.png': serveStaticFile(res, '/public/tmp/logo.png', 'image/png' ) break 老王2.2.11下载: serveStaticFile(res, '/public/404.html', 'text/html', 404 ) 老王v p n安卓版 } }) server.listen(port, () => console.log(`server started on port ${port}; ` + 'press Ctrl-C to terminate...')) |
Assuming you name the Node.js routing example helloworld3.js, you would start the router with the following command:
node helloworld3.js |
It should start the router. Enter the following URL:
http://localhost:3000 |
You should see a page rendered like the following:
As always, I hope this helps those trying to use this technology.
netfits云墙
with 2 comments
I want to add the MEAN (MongoDB, Express.js, Angular.js, and Node.js) stack to my backend server development course. This post documents the installation and configuration of components on Fedora 30.
The first step requires installing the Node package. The Node package also contains the Node package manager (npm). You install the Node packages as the root user or as a sudoer user with the following command.
yum install -y npm |
美国一天才程序员 暗中将工作外包给中国公司_中国广播网 ...:2021-1-17 · VPN登录记录显示，该账户从中国沈阳登录，但程序员本人就坐在位于美国的办公室里。这一切看上去都很蹊跷。 查出真相 公司明星程序员 竟将工作外包给沈阳公司 发现了VPN登录异常后，该公司就联系了电信供应商Verizon的安全部门寻求帮助。
Last metadata expiration check: 1:10:42 ago on Wed 08 Jul 2023 06:57:52 PM MDT. Dependencies resolved. ================================================================================================================================ Package Architecture Version Repository Size ================================================================================================================================ Installing: npm x86_64 1:6.13.4-1.10.19.0.1.fc30 updates 3.8 M Installing dependencies: nodejs x86_64 1:10.19.0-1.fc30 updates 88 k nodejs-libs x86_64 1:10.19.0-1.fc30 updates 9.1 M Installing weak dependencies: nodejs-full-i18n x86_64 1:10.19.0-1.fc30 updates 7.3 M Transaction Summary ================================================================================================================================ Install 4 Packages Total download size: 20 M Installed size: 91 M Downloading Packages: (1/4): nodejs-10.19.0-1.fc30.x86_64.rpm 173 kB/s | 88 kB 00:00 (2/4): nodejs-full-i18n-10.19.0-1.fc30.x86_64.rpm 2.8 MB/s | 7.3 MB 00:02 (3/4): nodejs-libs-10.19.0-1.fc30.x86_64.rpm 2.7 MB/s | 9.1 MB 00:03 (4/4): npm-6.13.4-1.10.19.0.1.fc30.x86_64.rpm 1.3 MB/s | 3.8 MB 00:02 -------------------------------------------------------------------------------------------------------------------------------- Total 4.9 MB/s | 20 MB 00:04 Running transaction check Transaction check succeeded. Running transaction test Transaction test succeeded. Running transaction Running scriptlet: npm-1:6.13.4-1.10.19.0.1.fc30.x86_64 1/1 Preparing : 1/1 Installing : nodejs-libs-1:10.19.0-1.fc30.x86_64 1/4 Installing : nodejs-full-i18n-1:10.19.0-1.fc30.x86_64 2/4 Installing : npm-1:6.13.4-1.10.19.0.1.fc30.x86_64 3/4 Installing : nodejs-1:10.19.0-1.fc30.x86_64 4/4 Running scriptlet: nodejs-1:10.19.0-1.fc30.x86_64 4/4 Verifying : nodejs-1:10.19.0-1.fc30.x86_64 1/4 Verifying : nodejs-full-i18n-1:10.19.0-1.fc30.x86_64 2/4 Verifying : nodejs-libs-1:10.19.0-1.fc30.x86_64 3/4 Verifying : npm-1:6.13.4-1.10.19.0.1.fc30.x86_64 4/4 Installed: nodejs-1:10.19.0-1.fc30.x86_64 nodejs-full-i18n-1:10.19.0-1.fc30.x86_64 nodejs-libs-1:10.19.0-1.fc30.x86_64 npm-1:6.13.4-1.10.19.0.1.fc30.x86_64 Complete! |
After installing the Node package, you should use the Node package manager (npm) to install the Node Monitor 老王vpm2.2.8下载安卓版. nodemon is a popular utility that automatically lets you restart Node programs when you make changes to the source code.
While npm is installed as part of the Node package, you must use npm to install the Node Monitor. The following command installs the nodemon globally on your Fedora system. The -g flag lets you install it globally, which is important when you manage package.json files.
npm install -g nodemon |
一个神奇的网站:2021-3-23 · 本站文章部分内容转载自互联网，供读者交流和学习，如有涉及作者版权问题请及时与我伊联系，伍便更正或删除。感谢所有提供信息材料的网站，并欢迎各类媒体与我伊进行文章共享合作。
Here’s a quick Hello World! example that I borrowed a JavaScript helloworld.js file from an excellent Web Development with Node & Express: Leveraging the JavaScript Stack by Ethan Brown. For those who haven’t worked with JavaScript in years, semicolons are optional now.
/* Construct a web server. */ const http = require('http') const port = process.env.PORT || 3000 const server = http.createServer((req, res) => { res.writeHead(200, { 'Content-Type': 'text/plain' }) res.end('Hello world!') }) server.listen(port, () => console.log(`server started on port ${port}); ` + 'press Ctrl-C to terminate...')) |
I put this in /var/www/html/node directory, which is owned by the superuser, root. You need to start the server before accessing it from a browser. You can start the program with the following syntax as a privileged user:
node /var/www/html/node/helloworld.js |
Then, you can use the localhost to access it with the following URL:
http://localhost:3000 |
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Next, you need to use the Node Package Manager (npm) to install the Express.js packages. You do that with the following syntax:
npm install -g express express-generator |
It should produce a console out put like the following:
npm WARN deprecated mkdirp@0.5.1: Legacy versions of mkdirp are no longer supported. Please update to mkdirp 1.x. (Note that the API surface has changed to use Promises in 1.x.) /usr/local/bin/express -> /usr/local/lib/node_modules/express-generator/bin/express-cli.js + express@4.17.1 + express-generator@4.16.1 added 60 packages from 42 contributors in 4.798s |
After you install all the packages, you can inspect them with the following command. The packages are found in the /usr/local/lib/node_modules/express directory. The listing is generated from the 老王vpm2.2.8下载安卓版 file on Fedora and Ubuntu Linux.
npm list -g |
It should display something like this:
/usr/local/lib ├─┬ express@4.17.1 │ ├─┬ accepts@1.3.7 │ │ ├─┬ mime-types@2.1.27 │ │ │ └── mime-db@1.44.0 │ │ └── negotiator@0.6.2 │ ├── array-flatten@1.1.1 │ ├─┬ body-parser@1.19.0 │ │ ├── bytes@3.1.0 │ │ ├── content-type@1.0.4 deduped │ │ ├── debug@2.6.9 deduped │ │ ├── depd@1.1.2 deduped │ │ ├─┬ http-errors@1.7.2 │ │ │ ├── depd@1.1.2 deduped │ │ │ ├── inherits@2.0.3 │ │ │ ├── setprototypeof@1.1.1 deduped │ │ │ ├── statuses@1.5.0 deduped │ │ │ └── toidentifier@1.0.0 │ │ ├─┬ iconv-lite@0.4.24 │ │ │ └── safer-buffer@2.1.2 │ │ ├── on-finished@2.3.0 deduped │ │ ├── qs@6.7.0 deduped │ │ ├─┬ raw-body@2.4.0 │ │ │ ├── bytes@3.1.0 deduped │ │ │ ├── http-errors@1.7.2 deduped │ │ │ ├── iconv-lite@0.4.24 deduped │ │ │ └── unpipe@1.0.0 deduped │ │ └── type-is@1.6.18 deduped │ ├─┬ content-disposition@0.5.3 │ │ └── safe-buffer@5.1.2 deduped │ ├── content-type@1.0.4 │ ├── cookie@0.4.0 │ ├── cookie-signature@1.0.6 │ ├─┬ debug@2.6.9 │ │ └── ms@2.0.0 │ ├── depd@1.1.2 │ ├── encodeurl@1.0.2 │ ├── escape-html@1.0.3 │ ├── etag@1.8.1 │ ├─┬ finalhandler@1.1.2 │ │ ├── debug@2.6.9 deduped │ │ ├── encodeurl@1.0.2 deduped │ │ ├── escape-html@1.0.3 deduped │ │ ├── on-finished@2.3.0 deduped │ │ ├── parseurl@1.3.3 deduped │ │ ├── statuses@1.5.0 deduped │ │ └── unpipe@1.0.0 │ ├── fresh@0.5.2 │ ├── merge-descriptors@1.0.1 │ ├── methods@1.1.2 │ ├─┬ on-finished@2.3.0 │ │ └── ee-first@1.1.1 │ ├── parseurl@1.3.3 │ ├── path-to-regexp@0.1.7 │ ├─┬ proxy-addr@2.0.6 │ │ ├── forwarded@0.1.2 │ │ └── ipaddr.js@1.9.1 │ ├── qs@6.7.0 │ ├── range-parser@1.2.1 │ ├── safe-buffer@5.1.2 │ ├─┬ send@0.17.1 │ │ ├── debug@2.6.9 deduped │ │ ├── depd@1.1.2 deduped │ │ ├── destroy@1.0.4 │ │ ├── encodeurl@1.0.2 deduped │ │ ├── escape-html@1.0.3 deduped │ │ ├── etag@1.8.1 deduped │ │ ├── fresh@0.5.2 deduped │ │ ├── http-errors@1.7.2 deduped │ │ ├── mime@1.6.0 │ │ ├── ms@2.1.1 │ │ ├── on-finished@2.3.0 deduped │ │ ├── range-parser@1.2.1 deduped │ │ └── statuses@1.5.0 deduped │ ├─┬ serve-static@1.14.1 │ │ ├── encodeurl@1.0.2 deduped │ │ ├── escape-html@1.0.3 deduped │ │ ├── parseurl@1.3.3 deduped │ │ └── send@0.17.1 deduped │ ├── setprototypeof@1.1.1 │ ├── statuses@1.5.0 │ ├─┬ type-is@1.6.18 │ │ ├── media-typer@0.3.0 │ │ └── mime-types@2.1.27 deduped │ ├── utils-merge@1.0.1 │ └── vary@1.1.2 └─┬ express-generator@4.16.1 ├── commander@2.15.1 ├── ejs@2.6.1 ├─┬ minimatch@3.0.4 │ └─┬ brace-expansion@1.1.11 │ ├── balanced-match@1.0.0 │ └── concat-map@0.0.1 ├─┬ mkdirp@0.5.1 │ └── minimist@0.0.8 └── sorted-object@2.0.1 |
You can also create a secure node site (HTTPS) with the following additional steps. They include creating a self-signed secure public and private key. This creates the public key:
openssl genrsa -out key.pem |
The openssl command will generate a private key key.pem file. It generates something like the following text message to console:
Generating RSA private key, 2048 bit long modulus (2 primes) ...........+++++ .............................................+++++ e is 65537 (0x010001) |
Next, you need to generate a self-signed certificate. You do this in two steps.
- Create a Distinguished Name (
DN) file. Thecsr.pemfile is theDNfile. You need it to create a self-signed certificate:openssl req -new -key key.pem -out csr.pem
It will prompt you for values, like the following:
You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [XX]: State or Province Name (full name) []:MiddleEarth Locality Name (eg, city) [Default City]:Rivendell Organization Name (eg, company) [Default Company Ltd]:Fellowship Organizational Unit Name (eg, section) []:Self Common Name (eg, your name or your server's hostname) []:Localhost Email Address []:bilbo@loth.org Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []:friend An optional company name []:Bilbo
- Use the DN file to create your secure certificate. The following
opensslcommand creates the certificate file by using your private keykey.pemandDNcsr.pemfiles.openssl x509 -req -days 9999 -in csr.pem -signkey key.pem -out cert.pem
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Signature ok subject=C = XX, ST = MiddleEarth, L = Rivendell, O = Fellowship, OU = Self, CN = Localhost, emailAddress = bilbo@loth.org Getting Private key
You can put these private key (key.pem) and certificate (cert.pem) files in an ssl subdirectory of the directory where you put the JavaScript program. The following creates a secure server page with the following code.
/* Construct a secure web server. */ const https = require('https') const fs = require('fs') const port = process.env.PORT || 3000 const options = { key: fs.readFileSync('ssl/key.pem'), cert: fs.readFileSync('ssl/cert.pem') } 老王app官方下载 server = https.createServer((options, res) => { res.老王vpm2.2.8下载安卓版(200, { 'Content-Type': 'text/plain' }) res.end('Hello world!') }) server.listen(port, () => console.log(`server started on port ${port}); ` + 'press Ctrl-C to terminate...')) |
If you try launch your browser using the localhost instead of a DNS or file resolved network name on the designated port, it will raise the following security error:
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An alternate approach to writing a secure server includes using 老王下载 library. The syntax changes somewhat and you include two new libraries, as shown below:
/* Construct a secure web server. */ 老王vpm2.2.8下载安卓版 https = require('https') const express = require('express') 老王 ⅴpn下载 fs = require('fs') const app = express() const port = process.env.PORT || 3001 const options = { key: fs.readFileSync('ssl/key.pem'), cert: fs.readFileSync('ssl/cert.pem') } https.createServer(options, app).listen(port, () => { console.log(`Express started in ${app.get('env')} mode ` + `on port + ${port}.`) }) |
This will fail with the following error message if you’re running it with a global installation unless you set the $NODE_PATH environment variable correctly. Without setting the variable you may get the following error message:
工信部回应“禁用VPN”：清理对象是无资质者_央广网:2021-7-25 · 工信部回应“禁用VPN”：清理对象是无资质者 在国务院新闻办今日举行的发布会上，有记者问及“有地方出台规定，对违法违规利用VPN上网加强管理”一事，工信部信息通信发展司司长闻库表示，不了 … |
Sometimes they’ll advise you to do an individual user installation of Express.js to get past this error but that’s not necessary. You just need to set the $NODE_PATH environment variable as follows:
export NODE_PATH=/usr/local/lib/node_modules |
This will enable the JavaScript to work without error and without a specific user installation. Assuming you name either of these programs as helloworldsecure.js, you run them with the following command:
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You can terminate the program with a Ctrl+c or if use the kill -15 pid command if you started it as a background process. You can find the process ID (pid) with the jobs command.
As always, I hope this is helpful to those starting out with this cool technology stack.
netfits云墙
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While teaching a class on the 老王2.2.11下载 (CLI), the book gave an example of generating a list of random US telephone numbers into a file. The book uses the RANDOM function to generate segments of the telephone number, and then the grep command to identify malformed telephone numbers.
My students wanted me to explain why the numbers were malformed. I had to explain that the RANDOM function returns a random number between 1 and 99,999. The RANDOM function may return a 1 to 5 digit random number, which means you may get a 1-digit or 2-digit number when you request a 3-digit random number or a 1- to 3-digit number when you request a 4-digit random number.
The author’s example is:
for i in {1..10}; do echo "(${RANDOM:0:3}) ${RANDOM:0:3}-${RANDOM:0:4}" >> list.txt done |
vpn被封翻墙党该何去何从？App Store连接不上如何解决？(图 ...:2021-1-29 · 前几天，据《环球时报》英文网报道中国已经开始屏蔽外国VPN服务，此消息也引起了国内“翻墙党”的一片震动。日前，工信部通信发展司司长闻库在接受采访时也被问到了这一问题，他回应称在中国发展互联网一定要按照中国的法律法规来进行，一些不良信息应该按照中国法律进行管理。
They seemed doubtful, so I wrote it for them. Here’s the script if you’re interested in learning more about bash shell scripting. While I implemented it with an bash array, that’s optional.
#!/usr/bin/bash # ============================================================ 老王v2.2.8下载 # Author: Michael McLaughlin 老王加速器永久免费 # ------------------------------------------------------------ # Purpose: Demonstrate how to generate random telehpone # numbers. The RANDOM function returns a random # number between 1 and 99999; and while you can # easily shave off a extra digit guarnteeing a # value above 100 is impossible without logic. # ============================================================ targetLength() { 上海交通大学_央广网 - cnr.cn:上海交通大学是我国历史最悠久、享誉海内外的高等学府之一，迄今已有121年历史。可伍用三句话来概括：百廿交大因图强而生，百廿交大因改革而兴，百廿交大因人才而盛。 老王vpm2.2.8下载安卓版='' # Check the number of parameters to process. if [[ ${#} = 2 ]]; then # Assign value to function-level and local variables. randomString=${1} formatLength=${2} # Get the length of the telephone number as integer. length=`echo -n ${randomString} | wc -c` # Calculate any shortfall. short=$((老王vpm2.2.8下载安卓版-老王app官方下载)) # Check if the telephone number is too short. if [[ ${short} > 0 ]]; then 老王v2.2.8下载=`echo "${randomString}${RANDOM:0:${short}}"` fi fi # Check if the combination of random numbers equals the target length # and assign the value to the global variable, or repeat processing # by making a recursive function call. if [[ `echo -n ${randomString} | wc -c` = ${formatLength} ]]; then result=${randomString} else targetLength ${randomString} 老王v2.2.8下载 fi } # Declare global variable to support targetLength(). result='' 老王vpm2.2.8下载安卓版 declare -A telephone_parts # Generate one hundred random telephone numbers. for i in {1..100}; do 工信部回应“禁用VPN”：清理对象是无资质者_央广网:2021-7-25 · 工信部回应“禁用VPN”：清理对象是无资质者 在国务院新闻办今日举行的发布会上，有记者问及“有地方出台规定，对违法违规利用VPN上网加强管理”一事，工信部信息通信发展司司长闻库表示，不了 … targetLength ${RANDOM:0:3} 3 telephone_parts[1]=${result} # Create random three digit prefix code. targetLength ${RANDOM:0:3} 3 telephone_parts[2]=${result} # Create random four digit number code. targetLength 老王vpm2.2.8下载安卓版 4 telephone_parts[3]=老王app下载 # Print the telephone numbers. 老王 ⅴpn下载 "[${i}] (${telephone_parts[1]}) ${telephone_parts[2]}-老王app下载" done |
For reference, a recursive function call isn’t required here. It could be done more effectively with the following while loop:
targetLength() { # Declare variable in function-level scope. randomString='' short=1 # Check the number of parameters to process. if [[ ${#} = 2 ]]; then # Assign value to function-level and local variables. randomString=${1} formatLength=老王2.2.11下载 # Check if the telephone number is too short. while [[ ${short} > 0 ]]; do # Get the length of the telephone number as integer. 老王加速器永久免费=`echo -n ${randomString} | wc -c` # Calculate any shortfall. short=$((${formatLength}-${length})) # Assign new value to randomString. randomString=`极光ⅴpn下载 "${randomString}${RANDOM:0:${short}}"` done # Assign randomString to global result variable. result=${randomString} fi } |
As always, I hope this helps those you want to learn or solve a problem.
netfits云墙
without comments
One of the key problems with Oracle’s deployment is that you can not use the up-arrow key to navigate the sqlplus command-line history. Here’s little Bash shell function that you can put in your .bashrc file. It requires you to have your system administrator install the rlwrap package, which wraps the sqlplus command-line history.
You should also set the $ORACLE_HOME environment variable before you put this function in your .bashrc file.
sqlplus () { # Discover the fully qualified program name. 老王app官方下载=`老王vp破解版最新版下载 rlwrap 2>/dev/null` file='' # Parse the program name from the path. if [ -n ${path} ]; then file=老王 2.2.7 fi; vpn被封翻墙党该何去何从？App Store连接不上如何解决？(图 ...:2021-1-29 · 前几天，据《环球时报》英文网报道中国已经开始屏蔽外国VPN服务，此消息也引起了国内“翻墙党”的一片震动。日前，工信部通信发展司司长闻库在接受采访时也被问到了这一问题，他回应称在中国发展互联网一定要按照中国的法律法规来进行，一些不良信息应该按照中国法律进行管理。 if [ -n ${file} ] && [[ ${file} = 老王 2.2.7 ]]; then rlwrap sqlplus "${@}" else echo "Command-line history unavailable: Install the rlwrap package." $ORACLE_HOME/bin/sqlplus "老王 2.2.7" fi } |
If you port this shell script to an environment where rlwrap is not installed, it simply prints the error message and advises you to install the rlwrap package.
As always, I hope this helps those looking for a solution.
netfits云墙
without comments
In April, when I updated from MySQL 8.0.17 to MySQL 8.0.19, I found that my Java connection example failed. That’s because of a change in the JDBC driver, which I blogged about then. Starting yesterday, I began updating a base Fedora 30 configuration again to MySQL 8.0.20. I wrote a testing program for the Java JDBC file last time, and when I ran it this time it told me that I didn’t have the JDBC driver installed, or in the $CLASSPATH. My Java diagnostic script, MySQLDriver.java, returned the following error message:
Error: Could not find or load main class MySQLDriver |
The Java JDBC test program code is in the prior post. It simply loads the user, password, database, host, and port statically for my student image, which you can update for your MySQL deployment.
You can find the MySQL 8.0 Connector/J installation in Chapter 4 of the MySQL Connector/J 8.0 Developer Guide. The link to page where you can download the Connector/J driver is in Chapter 4, but to save time you can click on the following 老王v2.2.8下载. You’ll find Ubuntu, Debian, SUSE Enterprise Linux Server, Red Hat Enterprise Linux/Oracle Linux, Fedora, Platform Independent, and Source Code at that download link.
I downloaded Fedora 30, 31, and 32 because eventually they get deprecated and sometimes I need the deprecated versions. Since Python 2.7 is deprecated, keeping an old Fedora 30 with both Python 2.7 and 3.7 is very attractive as a developer, keeping these Java libraries is also a potential convenience. On the Fedora 30 platform, you should download:
mysql-connector-java-8.0.20-1.fc30.noarch.rpm |
You install the RPM package with the following syntax:
rpm 老王v p n安卓版 mysql-connector-java-8.0.20-1.fc30.noarch.rpm |
It installs a single mysql-connector-java.jar file in the /usr/share/java directory. Then, you need to export the Java Archive file like so in your .bashrc file:
# Set the Java CLASSPATH path. export CLASSPATH=/usr/share/java/mysql-connector-java.jar:. |
Now, my MySQLDriver Java program returned:
Cannot connect to database server: The server time zone value 'MDT' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a 老王加速器永久免费 specifc time zone value if you want to utilize time zone support. |
As qualified in the prior post, it required me to add the following line to my /etc/my.cnf configuration file, which synchronizes the database’s timezone with the operating system.
# Synchronize the MySQL clock with the computer system clock. default-time-zone='+00:00' |
You need to restart the MySQL Daemon to apply the change, like:
sudo systemctl restart mysqld.service |
Then, running my MySQL Driver connection test program worked like a charm. It returns the following:
Database connection established MySQLDriver Version [8.0.20] Database connection terminated |
As always, I hope this helps those looking for a quick solution.
MySQL 8.0.20 Update
without comments
After I updated a Fedora 30 instance, I could no longer connect to the MySQL database. An attempt to connect raised the following error:
Error: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) |
My guess was correct, the mysqld.service got removed during the update (a synonym for upgrade). So, I ran the following command as a sudoer user:
老王vpm2.2.8下载安卓版 systemctl enable mysqld.service |
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Created symlink /etc/systemd/system/multi-user.target.wants/mysqld.service → /usr/lib/systemd/system/mysqld.service. |
That would start the MySQL Daemon (mysqld) on the next restart of the OS. However, I didn’t want to restart to have access to the service. I simply started it with the following command:
sudo systemctl start mysqld.service |
Then, I could connect to the MySQL database. As always, I hope this helps those looking for a solution.
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