London | Ameneh Keshavarz | Implement-shell-tools| WEEK3

implement-shell-tools/cat/cat.js

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+const { promises: fs } = require("fs");
+const { program } = require("commander");
+
+program
+  .name("cat")
+  .description("Implement a version of the cat program")
+  .option("-n, --number", "Number all output lines, starting at 1")
+  .option("-b, --number2", "Number non-empty output lines, starting at 1")
+  .argument("<paths...>", "The file paths to process")
+  .parse();
+
+const { number: nOption, number2: bOption } = program.opts();
+const paths = program.args;
+
+let lineNumber = 1;
+let nonEmptyLineNumber = 1;
+
+function printLinesWithOptions(lines) {
+  lines.forEach(line => {
+    if (nOption) {
+      console.log(`${String(lineNumber++).padStart(6)}  ${line}`);
+    } else if (bOption && line.trim()) {
+      console.log(`${String(nonEmptyLineNumber++).padStart(6)}  ${line}`);
+    } else {
+      console.log(line);
+    }
+  });
+}
+
+async function readFileContent(path) {
+  try {
+    const content = await fs.readFile(path, "utf-8");
+    const lines = content.split("\n");
+    printLinesWithOptions(lines);
+  } catch (err) {
+    console.error(`Error reading file ${path}: ${err.message}`);
+  }
+}
+
+Promise.all(paths.map(readFileContent));

implement-shell-tools/ls/ls.js

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+const fs = require('fs');
+const { program } = require('commander');
+
+program
+  .option('-a, --all', 'Show hidden files')
+  .option('-1', 'Show one file per line')
+  .argument('[dirPaths...]', 'Directory paths', ['.']) // Support multiple directories
+  .parse(process.argv);
+
+const { all, '1': onePerLine } = program.opts();
+const dirPaths = program.args;
+
+function listDirectoryContents(dirPath, showHidden = false, onePerLine = false) {
+  fs.readdir(dirPath, (err, files) => {
+    if (err) {
+      console.error(`Error reading directory '${dirPath}': ${err.message}`);
+      return;
+    }
+
+    if (!showHidden) {
+      files = files.filter(file => !file.startsWith('.'));
+    }
+
+    console.log(`\n${dirPath}:`);
+    if (onePerLine) {
+      files.forEach(file => console.log(file));
+    } else {
+      console.log(files.join(' '));
+    }
+  });
+}
+
+dirPaths.forEach(dirPath => {
+  if (typeof dirPath !== 'string') {
+    console.error(`Error: Invalid directory path '${dirPath}'`);
+    return;
+  }
+  listDirectoryContents(dirPath, all, onePerLine);
+});

implement-shell-tools/package.json

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+{
+    "type": "commonjs",
+    "dependencies": {
+      "commander": "^11.0.0"
+    }
+  }
+

implement-shell-tools/wc/wc.js

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+const { promises: fs } = require('fs');
+const path = require('path');
+const { program } = require('commander');
+
+program
+  .description('Count lines, words, and characters in the specified files')
+  .option('-l, --lines', 'Count the lines')
+  .option('-w, --words', 'Count the words')
+  .option('-c, --characters', 'Count the characters')
+  .parse(process.argv);
+
+const options = program.opts();
+const files = program.args;
+
+if (files.length === 0) {
+  console.error("Error: No files provided.");
+  process.exit(1);
+}
+
+async function countFileStats(filePath, options) {
+  try {
+    const data = await fs.readFile(filePath, 'utf8');
+
+    const lines = (data.match(/\n/g) || []).length;
+    const words = data.split(/\s+/).filter(Boolean).length;
+    const characters = data.length;
+
+    const result = { lines, words, characters };
+    const output = [];
+    if (options.lines) output.push(result.lines);
+    if (options.words) output.push(result.words);
+    if (options.characters) output.push(result.characters);
+    if (output.length === 0) output.push(result.lines, result.words, result.characters);
+
+    return { file: filePath, output: output.join(' '), lines, words, characters };
+  } catch (err) {
+    console.error(`Error reading file: ${filePath}`);
+    return null;
+  }
+}
+
+async function processFiles() {
+  let totalLines = 0;
+  let totalWords = 0;
+  let totalCharacters = 0;
+
+  for (const file of files) {
+    const filePath = path.resolve(file);
+    const result = await countFileStats(filePath, options);
+
+    if (result) {
+      console.log(result.output, file);
+      totalLines += result.lines;
+      totalWords += result.words;
+      totalCharacters += result.characters;
+    }
+  }
+
+  if (files.length > 1) {
+    const totals = [];
+    if (options.lines) totals.push(totalLines);
+    if (options.words) totals.push(totalWords);
+    if (options.characters !== false) totals.push(totalCharacters);
+
+    if (totals.length > 0) {
+      console.log(totals.join(' ') + ' total');
+    }
+  }
+}
+
+processFiles();