Chapter 2 Coordinating IO

2-Coordinating-IO/source/communicating-over-sockets/client.js

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+'use strict'
+
+const net = require('net')
+
+const socket = net.connect(1337, 'localhost')
+const name = process.argv[2] || 'Dave'
+
+socket.write(name)
+
+socket.on('data', (data) => {
+  console.log(data.toString())
+})
+
+socket.on('close', () => {
+  console.log('-> disconnected by server')
+})

2-Coordinating-IO/source/communicating-over-sockets/net-sockets-are-streams/client.js

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+'use strict'
+
+const net = require('net')
+
+const socket = net.connect(1337)
+const name = process.argv[2] || 'Dave'
+
+socket.write(name)
+
+socket.pipe(process.stdout)
+
+socket.on('close', () => {
+  console.log('-> disconnected by server')
+})

2-Coordinating-IO/source/communicating-over-sockets/net-sockets-are-streams/echo-client.js

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+'use strict'
+
+process.stdin.pipe(require('net').connect(1338)).pipe(process.stdout)

2-Coordinating-IO/source/communicating-over-sockets/net-sockets-are-streams/echo-server.js

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+'use strict'
+
+require('net').createServer((socket) => socket.pipe(socket)).listen(1338)

2-Coordinating-IO/source/communicating-over-sockets/net-sockets-are-streams/server.js

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+'use strict'
+
+const net = require('net')
+
+net.createServer((socket) => {
+  console.log('-> client connected')
+  socket.once('data', name => {
+    socket.write(`Hi ${name}!`)
+  })
+  socket.on('close', () => {
+    console.log('-> client disconnected')
+  })
+}).listen(1337)

2-Coordinating-IO/source/communicating-over-sockets/server.js

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+'use strict'
+
+const net = require('net')
+
+net.createServer((socket) => {
+  console.log('-> client connected')
+  socket.on('data', name => {
+    socket.write(`Hi ${name}!`)
+  })
+  socket.on('close', () => {
+    console.log('-> client disconnected')
+  })
+}).listen(1337, 'localhost')

2-Coordinating-IO/source/communicating-over-sockets/udp-sockets/client.js

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+'use strict'
+
+const dgram = require('dgram')
+
+const socket = dgram.createSocket('udp4')
+const name = process.argv[2] || 'Dave'
+
+socket.bind(1400)
+socket.send(name, 1339)
+
+socket.on('message', (data) => {
+  console.log(data.toString())
+})

2-Coordinating-IO/source/communicating-over-sockets/udp-sockets/server.js

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+'use strict'
+
+const dgram = require('dgram')
+
+const socket = dgram.createSocket('udp4')
+socket.bind(1339)
+
+socket.on('message', (name) => {
+  socket.send(`Hi ${name}!`, 1400)
+})

2-Coordinating-IO/source/communicating-over-sockets/unix-sockets/client.js

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+'use strict'
+
+const net = require('net')
+
+const socket = net.connect('/tmp/my.socket')
+const name = process.argv[2] || 'Dave'
+
+socket.write(name)
+
+socket.on('data', (data) => {
+  console.log(data.toString())
+})
+
+socket.on('close', () => {
+  console.log('-> disconnected by server')
+})

2-Coordinating-IO/source/communicating-over-sockets/unix-sockets/server.js

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+'use strict'
+
+const net = require('net')
+
+net.createServer((socket) => {
+  console.log('-> client connected')
+  socket.on('data', name => {
+    socket.write(`Hi ${name}!`)
+  })
+  socket.on('close', () => {
+    console.log('-> client disconnected')
+  })
+}).listen('/tmp/my.socket')

2-Coordinating-IO/source/fetching-meta-data/checking-file-existence/check.js

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+'use strict'
+
+const fs = require('fs')
+
+const exists = (file) => new Promise((resolve, reject) => {
+  fs.access(file, (err) => {
+    if (err) {
+      if (err.code !== 'ENOENT') { return reject(err) }
+      return resolve({file, exists: false})
+    }
+    resolve({file, exists: true})
+  })  
+})
+
+exists(process.argv[2])
+  .then(({file, exists}) => console.log(`"${file}" does${exists ? '' : ' not'} exist`))
+  .catch(console.error)

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/meta.js

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+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+const tableaux = require('tableaux')
+
+const write = tableaux(
+  {name: 'Name', size: 20},
+  {name: 'Created', size: 30},
+  {name: 'Inode', size: 10},
+  {name: 'Mode', size: 8},
+  {name: 'Lnks', size: 4},
+  {name: 'Size', size:  6}
+)
+
+function print(dir) {
+  fs.readdirSync(dir)
+    .map((file) => ({file, dir}))
+    .map(toMeta)
+    .forEach(output)
+  write.newline()
+}
+
+function toMeta({file, dir}) {
+  const stats = fs.lstatSync(path.join(dir, file))
+  let {birthtime, ino, mode, nlink, size} = stats
+  birthtime = birthtime.toUTCString()
+  mode = mode.toString(8)
+  size += 'B'
+  return {
+    file,
+    dir,
+    info: [birthtime, ino, mode, nlink, size],
+    isDir: stats.isDirectory(),
+    isSymLink: stats.isSymbolicLink()
+  }
+}
+
+function output({file, dir, info, isDir, isSymLink}) {
+  if (isSymLink) {
+    outputSymlink(file, dir, info)
+    return
+  }
+  write(file, ...info)
+  if (!isDir) { return }
+  const p = path.join(dir, file)
+  write.arrow()
+  fs.readdirSync(p).forEach((f) => {
+    const stats = fs.lstatSync(path.join(p, f))
+    const style = stats.isDirectory() ? 'bold' : 'dim'
+    if (stats.isSymbolicLink()) { f = '\u001b[33m' + f + '\u001b[0m'}
+    write[style](f)
+  })
+  write.newline()
+}
+
+function outputSymlink(file, dir, info) {
+  write('\u001b[33m' + file + '\u001b[0m', ...info)
+  process.stdout.write('\u001b[33m')
+  write.arrow(4)
+  write.bold(fs.readlinkSync(path.join(dir, file)))
+  process.stdout.write('\u001b[0m')
+  write.newline()
+}
+
+print(process.argv[2] || '.')

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/absolute-symlink

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+/tmp

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/link-to-symlink

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+my-symlink

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/my-file

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+my edit

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/my-subdir/subdir-symlink

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+another-file

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/my-symlink

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+my-file

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/relative-symlink

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+../meta.js

2-Coordinating-IO/source/fetching-meta-data/getting-symlink-information/my-folder/too-deep

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+my-subdir/my-subsubdir/too-deep

2-Coordinating-IO/source/fetching-meta-data/manipulating-meta-data/make-file-efficiently.js

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+'use strict'
+
+const fs = require('fs')
+const {execSync} = require('child_process')
+
+const file = process.argv[2]
+if (!file) { 
+  console.error('specify a file')
+  process.exit(1)
+}
+try {
+  fs.accessSync(file)
+  console.error('file already exists')
+  process.exit(1)
+} catch (e) {
+  makeIt()
+}
+
+function makeIt() {
+  const nobody = Number(execSync('id -u nobody').toString().trim())
+  const fd = fs.openSync(file, 'w')
+  fs.fchmodSync(fd, 0)
+  fs.fchownSync(fd, nobody, nobody)
+  console.log(file + ' created')
+}
+

2-Coordinating-IO/source/fetching-meta-data/manipulating-meta-data/make-file.js

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+'use strict'
+
+const fs = require('fs')
+const {execSync} = require('child_process')
+
+const file = process.argv[2]
+if (!file) { 
+  console.error('specify a file')
+  process.exit(1)
+}
+try {
+  fs.accessSync(file)
+  console.error('file already exists')
+  process.exit(1)
+} catch (e) {
+  makeIt()
+}
+
+function makeIt() {
+  const nobody = Number(execSync('id -u nobody').toString().trim())
+  fs.writeFileSync(file, '')
+  fs.chownSync(file, nobody, nobody)
+  fs.chmodSync(file, 0)
+  console.log(file + ' created')
+}

2-Coordinating-IO/source/fetching-meta-data/meta.js

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+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+const tableaux = require('tableaux')
+
+const write = tableaux(
+  {name: 'Name', size: 20},
+  {name: 'Created', size: 30},
+  {name: 'Inode', size: 10},
+  {name: 'Mode', size: 8},
+  {name: 'Lnks', size: 4},
+  {name: 'Size', size:  6}
+)
+
+function print(dir) {
+  fs.readdirSync(dir)
+    .map((file) => ({file, dir}))
+    .map(toMeta)
+    .forEach(output)
+  write.newline()
+}
+
+function toMeta({file, dir}) {
+  const stats = fs.statSync(path.join(dir, file))
+  let {birthtime, ino, mode, nlink, size} = stats
+  birthtime = birthtime.toUTCString()
+  mode = mode.toString(8)
+  size += 'B'
+  return {
+    file,
+    dir,
+    info: [birthtime, ino, mode, nlink, size],
+    isDir: stats.isDirectory()
+  }
+}
+
+function output({file, dir, info, isDir}) {
+  write(file, ...info)
+  if (!isDir) { return }
+  const p = path.join(dir, file)
+  write.arrow()
+  fs.readdirSync(p).forEach((f) => {
+    const stats = fs.statSync(path.join(p, f))
+    const style = stats.isDirectory() ? 'bold' : 'dim'
+    write[style](f)
+  })
+  write.newline()
+}
+
+print(process.argv[2] || '.')

2-Coordinating-IO/source/fetching-meta-data/my-folder/my-file

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+my edit

2-Coordinating-IO/source/fetching-meta-data/my-folder/my-symlink

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+my-file

2-Coordinating-IO/source/fetching-meta-data/package.json

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+{
+  "name": "fetching-meta-data",
+  "version": "1.0.0",
+  "description": "",
+  "main": "meta.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "David Mark Clements",
+  "license": "MIT",
+  "dependencies": {
+    "tableaux": "^1.0.1"
+  }
+}

2-Coordinating-IO/source/interfacing-with-standard-io/base64.js

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+'use strict'
+
+process.stdin.on('data', data => {
+  process.stderr.write(`Converting: "${data}" to base64\n`)
+  process.stdout.write(data.toString('base64') + '\n')
+})

2-Coordinating-IO/source/interfacing-with-standard-io/piping/base64.js

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+'use strict'
+
+const encode = require('base64-encode-stream')
+process.stdin.pipe(encode()).pipe(process.stdout)

2-Coordinating-IO/source/interfacing-with-standard-io/piping/package.json

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+{
+  "name": "piping",
+  "version": "1.0.0",
+  "main": "base64.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "David Mark Clements",
+  "license": "MIT",
+  "dependencies": {
+    "base64-encode-stream": "^1.0.0"
+  },
+  "devDependencies": {},
+  "keywords": [],
+  "description": ""
+}

2-Coordinating-IO/source/watching-files-and-directories/my-file.txt

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+back again