yanzhou-git · yanzhou-git · Apr 12, 2026 · Apr 12, 2026 · Apr 12, 2026
diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,49 @@
+import process from "node:process";
+import { promises as fs } from "node:fs";
+import { program } from "commander";
+
+program
+  .name("cat")
+  .description("Concatenate and print files")
+  .option("-n, --number", "Number all lines", false)
+  .option("-b, --number-nonblank", "Number non-empty lines", false)
+  .argument("<path...>", "The file(s) to read");
+
+program.parse();
+
+const paths = program.args;
+if (paths.length === 0) {
+  console.error("Please provide at least one file");
+  process.exit(1);
+}
+
+const options = program.opts();
+const showLineNumbers = options.number;
+const numberNonEmpty = options.numberNonblank;
+
+let lineNumber = 1;
+
+for (const path of paths) {
+  try {
+    const content = await fs.readFile(path, "utf-8");
+    const lines = content.split("\n");
+
+    for (const line of lines) {
+      if (numberNonEmpty) {
+        if (line.trim() !== "") {
+          console.log(`${lineNumber} ${line}`);
+          lineNumber++;
+        } else {
+          console.log("");
+        }
+      } else if (showLineNumbers) {
+        console.log(`${lineNumber} ${line}`);
+        lineNumber++;
+      } else {
+        console.log(line);
+      }
+    }
+  } catch (err) {
+    console.error(`Error reading file: ${path}`);
+  }
+}
diff --git a/implement-shell-tools/cat/package-lock.json b/implement-shell-tools/cat/package-lock.json
diff --git a/implement-shell-tools/cat/package.json b/implement-shell-tools/cat/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "cat",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `cat` command line tool.",
+  "main": "cat.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}
diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
@@ -0,0 +1,40 @@
+import process from "node:process";
+import { promises as fs } from "node:fs";
+import { program } from "commander";
+
+program
+  .name("ls")
+  .description("List directory contents")
+  .option("-1", "List one file per line")
+  .option("-a, --all", "Include hidden files", false)
+  .argument("[path]", "Directory path", ".");
+
+program.parse();
+
+const path = program.args[0] || ".";
+const options = program.opts();
+
+const showAll = options.all;
+
+try {
+  const stat = await fs.stat(path);
+
+  if (stat.isDirectory()) {
+    const files = await fs.readdir(path);
+
+    let filteredFiles = files;
+
+    if (!showAll) {
+      filteredFiles = files.filter((file) => !file.startsWith("."));
+    }
+
+    for (const file of filteredFiles) {
+      console.log(file);
+    }
+  } else {
+    console.log(path);
+  }
+} catch (err) {
+  console.error(`Error: cannot access ${path}`);
+  process.exit(1);
+}
diff --git a/implement-shell-tools/ls/package-lock.json b/implement-shell-tools/ls/package-lock.json
diff --git a/implement-shell-tools/ls/package.json b/implement-shell-tools/ls/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "ls",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `ls` command line tool.",
+  "main": "ls.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}
diff --git a/implement-shell-tools/wc/package-lock.json b/implement-shell-tools/wc/package-lock.json
diff --git a/implement-shell-tools/wc/package.json b/implement-shell-tools/wc/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "wc",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `wc` command line tool.",
+  "main": "wc.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.3"
+  }
+}
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
@@ -0,0 +1,60 @@
+import process from "node:process";
+import { promises as fs } from "node:fs";
+import { program } from "commander";
+
+program
+  .name("wc")
+  .description("Word, line, and byte count")
+  .option("-l, --lines", "Count lines")
+  .option("-w, --words", "Count words")
+  .option("-c, --bytes", "Count bytes")
+  .argument("<paths...", "File to process");
+
+program.parse();
+
+const paths = program.args;
+const options = program.opts();
+
+if (paths.length === 0) {
+  console.error("Please provide at least one file.");
+  process.exit(1);
+}
+
+let totalLines = 0;
+let totalWords = 0;
+let totalBytes = 0;
+
+for (const path of paths) {
+  try {
+    const content = await fs.readFile(path, "utf-8");
+
+    const lines = content.split("\n").length - 1;
+    const words =
+      content.trim() === "" ? 0 : content.trim().split(/\s+/).length;
+    const bytes = Buffer.byteLength(content, "utf-8");
+
+    totalLines += lines;
+    totalWords += words;
+    totalBytes += bytes;
+
+    printResult(lines, words, bytes, path, options);
+  } catch (err) {
+    console.error(`Error reading file: ${path}`);
+  }
+}
+
+if (paths.length > 1) {
+  printResult(totalLines, totalWords, totalBytes, "total", options);
+}
+
+function printResult(lines, words, bytes, label, options) {
+  if (options.lines) {
+    console.log(`${lines} ${label}`);
+  } else if (options.words) {
+    console.log(`${words} ${label}`);
+  } else if (options.bytes) {
+    console.log(`${bytes} ${label}`);
+  } else {
+    console.log(`${lines} ${words} ${bytes} ${label}`);
+  }
+}