cat, ls, wc commands

Author: delmorallopez

implement-shell-tools/cat/script-01.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+//import process from "node:process";
+
+// Setup CLI with commander
+program
+    .name("count-containing-words")
+    .description("Counts words in a file that contain a particular character")
+    .option("-c, --char <char>", "The character to search for", "e")
+    .argument("<path>", "The file path to process");
+
+// Parse CLI arguments    
+program.parse();
+const argv = program.args;
+
+// Validate arguments
+if (argv.length != 1) {
+    console.error(`Expected exactly 1 argument (a path) to be passed but got ${argv.length}.`);
+    process.exit(1);
+}
+
+
+const path = argv[0];
+const char = program.opts().char;
+
+// Read file content
+const content = await fs.readFile(path, "utf-8");
+console.log("content",content)
+
+// Count words containing the character
+const countOfWordsContainingChar = content
+  .split(" ")
+  .filter((word) => word.includes(char))
+  .length;
+console.log(countOfWordsContainingChar);
+

implement-shell-tools/ls/script-01.js

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+#!/usr/bin/env node
+import { program } from "commander";
+import fs from "fs";
+import path from "path";
+
+// Define CLI
+program
+  .name("ls-clone")
+  .description("A simple implementation of ls")
+  .option("-1", "list one file per line")
+  .option("-a", "include hidden files")
+  .argument("[dirs...]", "directories to list", "."); // default is current dir
+
+program.parse();
+
+const options = program.opts();
+const dirs = program.args.length ? program.args : ["."];
+const onePerLine = options["1"];
+const showAll = options.a;
+
+for (const dir of dirs) {
+  let files;
+  try {
+    files = fs.readdirSync(dir);
+  } catch (err) {
+    console.error(`ls-clone: cannot access '${dir}': No such file or directory`);
+    continue;
+  }
+
+  if (!showAll) {
+    files = files.filter(name => !name.startsWith("."));
+  }
+
+  // Output
+  if (onePerLine) {
+    files.forEach(f => console.log(f));
+  } else {
+    console.log(files.join("  "));
+  }
+}

implement-shell-tools/wc/script-01.js

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+#!/usr/bin/env node
+import { program } from "commander";
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+// Setup CLI with commander
+program
+  .name("wc-clone")
+  .description("A simplified implementation of the wc command")
+  .option("-l", "count lines")
+  .option("-w", "count words")
+  .option("-c", "count bytes")
+  .argument("[files...]", "files to process");
+
+program.parse();
+
+const options = program.opts();
+const files = program.args;
+
+if (files.length === 0) {
+  console.error("Please provide at least one file.");
+  process.exit(1);
+}
+
+// Helper function to count lines, words, bytes
+function countContent(content) {
+  const lines = content.split("\n").length;
+  const words = content.trim().split(/\s+/).filter(Boolean).length;
+  const bytes = Buffer.byteLength(content, "utf-8");
+  return { lines, words, bytes };
+}
+
+// Process each file
+(async () => {
+  let total = { lines: 0, words: 0, bytes: 0 };
+  let multipleFiles = files.length > 1;
+
+  for (const file of files) {
+    let content;
+    try {
+      content = await fs.readFile(file, "utf-8");
+    } catch (err) {
+      console.error(`wc-clone: cannot open '${file}': No such file`);
+      continue;
+    }
+
+    const counts = countContent(content);
+
+    total.lines += counts.lines;
+    total.words += counts.words;
+    total.bytes += counts.bytes;
+
+    // Determine what to display
+    let output = "";
+    if (options.l) output += `${counts.lines.toString().padStart(8)} `;
+    if (options.w) output += `${counts.words.toString().padStart(8)} `;
+    if (options.c) output += `${counts.bytes.toString().padStart(8)} `;
+    if (!options.l && !options.w && !options.c) {
+      // default: all counts
+      output = `${counts.lines.toString().padStart(8)} ${counts.words.toString().padStart(8)} ${counts.bytes.toString().padStart(8)} `;
+    }
+
+    output += file;
+    console.log(output);
+  }
+
+  // If multiple files, show total
+  if (multipleFiles) {
+    let output = "";
+    if (options.l) output += `${total.lines.toString().padStart(8)} `;
+    if (options.w) output += `${total.words.toString().padStart(8)} `;
+    if (options.c) output += `${total.bytes.toString().padStart(8)} `;
+    if (!options.l && !options.w && !options.c) {
+      output = `${total.lines.toString().padStart(8)} ${total.words.toString().padStart(8)} ${total.bytes.toString().padStart(8)} `;
+    }
+    output += "total";
+    console.log(output);
+  }
+})();