Sheffield | 2026-MAR-SDC | Jak Rhodes-Smith | Sprint 3 | Implement shell tools

implement-shell-tools/cat/cat.js

@@ -0,0 +1,38 @@
+import { program } from "commander";
+import * as fs from "node:fs/promises";
+
+program
+  .name("cat")
+  .description("Reads file(s) and writes them to the standard output")
+  .argument("<paths...>", "The file path(s) to process")
+  .option("-n", "Number the output lines, starting at 1.")
+  .option("-b", "Number only non-blank output lines, starting at 1.");
+
+program.parse();
+
+try {
+  const filePaths = program.args;
+
+  const options = program.opts();
+
+  for (const filePath of filePaths) {
+    const file = await fs.open(filePath);
+
+    let lineNum = 1;
+
+    try {
+      for await (const line of file.readLines()) {
+        const isBlank = line.trim() === "";
+        const shouldNumber = options.n || (options.b && !isBlank);
+
+        console.log(shouldNumber ? `${lineNum}  ${line}` : line);
+
+        if (shouldNumber) lineNum++;
+      }
+    } finally {
+      await file.close();
+    }
+  }
+} catch (err) {
+  console.error(err.message);
+}

implement-shell-tools/cat/package.json

@@ -0,0 +1,6 @@
+{
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}

implement-shell-tools/ls/ls.js

@@ -0,0 +1,67 @@
+import { program } from "commander";
+import * as fs from "node:fs/promises";
+
+program
+  .name("ls")
+  .description("List directory contents")
+  .argument(
+    "[paths...]",
+    "The file path to process (defaults to current directory)",
+  )
+  .option("-a", "Include directory entries whose names begin with a dot ('.').")
+  .option("-1", "Force output to be one entry per line.");
+
+program.parse();
+
+try {
+  let filePaths = program.args;
+  if (!filePaths || filePaths.length === 0) {
+    filePaths = ["."];
+  }
+
+  const options = program.opts();
+  const includeHidden = Boolean(options.a);
+  const onePerLine = Boolean(options["1"]);
+
+  const result = { files: [], dirs: {} };
+
+  for (const filePath of filePaths) {
+    const stats = await fs.stat(filePath);
+    if (stats.isFile()) result.files.push(filePath);
+    if (stats.isDirectory()) {
+      result.dirs[filePath] = await fs.readdir(filePath);
+    }
+  }
+
+  const filterHidden = (files) => files.filter((file) => !file.startsWith("."));
+
+  const getVisibleEntries = (files) =>
+    includeHidden ? files : filterHidden(files);
+
+  const formatEntries = (files) => {
+    if (files.length === 0) return;
+    console.log(files.join(onePerLine ? "\n" : "\t"));
+  };
+
+  result.files = getVisibleEntries(result.files);
+
+  if (filePaths.length === 1) {
+    let entries = [...result.files];
+
+    for (const [dir, contents] of Object.entries(result.dirs)) {
+      const filtered = getVisibleEntries(contents);
+      entries = entries.concat(filtered);
+    }
+    formatEntries(entries);
+  } else {
+    formatEntries(result.files);
+
+    for (const [dir, contents] of Object.entries(result.dirs)) {
+      console.log("\n" + dir + ":");
+      const filtered = getVisibleEntries(contents);
+      formatEntries(filtered);
+    }
+  }
+} catch (err) {
+  console.error(err.message);
+}

implement-shell-tools/ls/package.json

@@ -0,0 +1,6 @@
+{
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}

implement-shell-tools/wc/package.json

@@ -0,0 +1,6 @@
+{
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}

implement-shell-tools/wc/wc.js

@@ -0,0 +1,65 @@
+import { program } from "commander";
+import * as fs from "node:fs/promises";
+
+program
+  .name("wc")
+  .description("word, line and byte count")
+  .argument("<paths...>", "The file path(s) to process.")
+  .option(
+    "-l, --lines",
+    "The number of lines in each input file is written to the standard output.",
+  )
+  .option(
+    "-w, --words",
+    "The number of words in each input file is written to the standard output.",
+  )
+  .option(
+    "-c --bytes",
+    "The number of bytes in each input file is written to the standard output.",
+  );
+
+program.parse();
+
+try {
+  const filePaths = program.args;
+  const results = {};
+
+  for (const filePath of filePaths) {
+    const file = await fs.open(filePath);
+    const stats = await fs.stat(filePath);
+    const count = { lines: 0, words: 0, bytes: stats.size };
+
+    try {
+      for await (const line of file.readLines()) {
+        count.lines++;
+        const trimmed = line.trim();
+        if (trimmed.length > 0) {
+          count.words += trimmed.split(/\s+/).length;
+        }
+      }
+    } finally {
+      await file.close();
+    }
+    results[filePath] = count;
+  }
+
+  if (filePaths.length > 1) {
+    const total = { lines: 0, words: 0, bytes: 0 };
+    for (const file of Object.values(results)) {
+      total.lines += file.lines;
+      total.words += file.words;
+      total.bytes += file.bytes;
+    }
+    results["total"] = total;
+  }
+
+  const options = program.opts();
+  const noOptionsProvided = !Object.keys(options).length;
+  const selectedOptionKeys = [...Object.keys(options)];
+
+  noOptionsProvided
+    ? console.table(results)
+    : console.table(results, selectedOptionKeys);
+} catch (err) {
+  console.error(err.message);
+}