London | 25-SDC-July | Priscilla Emebo | Sprint 3 | Implement shell tools

implement-shell-tools/cat/mycat.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+program
+  .name("mycat")
+  .description("Outputs the content of the given file(s), like the cat command")
+  .option("-n", "Number all lines")
+  .option("-b", "Number non-blank lines only")
+  .argument("<files...>", "File paths to display");
+
+program.parse();
+
+const options = program.opts();
+const filePaths = program.args;
+
+let lineNumber = 1;
+
+for (const path of filePaths) {
+  try {
+    const content = await fs.readFile(path, "utf-8");
+    const lines = content.trimEnd().split("\n");
+
+    for (const line of lines) {
+      const isBlank = line.trim() === "";
+
+      if (options.b) {
+        // -b: number only non-blank lines
+        if (!isBlank) {
+          process.stdout.write(`${String(lineNumber).padStart(6)}  ${line}\n`);
+          lineNumber++;
+        } else {
+          process.stdout.write("\n");
+        }
+      } else if (options.n) {
+        // -n: number all lines
+        process.stdout.write(`${String(lineNumber).padStart(6)}  ${line}\n`);
+        lineNumber++;
+      } else {
+        // no flags
+        process.stdout.write(line + "\n");
+      }
+    }
+  } catch (error) {
+    process.stderr.write(`Error reading file ${path}: ${error.message}\n`);
+    process.exit(1);
+  }
+}

implement-shell-tools/cat/package.json

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+{
+  "name": "cat",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `cat` command line tool.",
+  "main": "mycat.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "commander": "^14.0.0"
+  }
+}

implement-shell-tools/ls/myls.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+program
+  .name("myls")
+  .description("list file(s) in the directory, like the ls command")
+  .option("-1", "list one file per line")
+  .option("-a", "include hidden files")
+  .argument("[directory]", "Directory to list", ".");
+
+program.parse();
+
+const options = program.opts();
+const directory = program.args[0] || ".";
+
+try {
+  let files = await fs.readdir(directory);
+
+  // if "-a" is used, include hidden files; those that start with "." 
+  if (options.a) {
+    files = [".", "..", ...files];
+  }
+
+  for (const file of files) {
+    // if "-a" is not used, skip hidden files; those that start with "."
+    if (!options.a && file.startsWith(".")) {
+      continue;
+    }
+
+    console.log(file); // print file name; one file per line
+  }
+} catch (error) {
+  console.error(`Error reading directory ${directory}:`, error.message);
+  process.exit(1);
+}

implement-shell-tools/ls/package.json

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+{
+  "name": "ls",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `ls` command line tool.",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "commander": "^14.0.0"
+  }
+}

implement-shell-tools/wc/mywc.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+program
+  .name("mywc")
+  .description(
+    "Counts lines, words, and bytes in files like the Unix wc command"
+  )
+  .option("-l", "counts the number of lines")
+  .option("-w", "counts words")
+  .option("-c", "counts bytes")
+  .argument("<files...>", "Files to count");
+
+program.parse();
+
+const options = program.opts();
+const files = program.args; 
+
+// If there are no given flags, default to counting lines, words and bytes like the Unix wc command
+if (!options.l && !options.w && !options.c) {
+  options.l = true;
+  options.w = true;
+  options.c = true;
+}
+
+const showLines = options.l;
+const showWords = options.w;
+const showBytes = options.c;
+
+// To support multiple files and a total
+let totalLines = 0;
+let totalWords = 0;
+let totalBytes = 0;
+
+for (const file of files) {
+  try {
+    const content = await fs.readFile(file, "utf-8");
+
+    const lineCount = content.split("\n").length - 1;
+    const wordCount = content.trim().split(/\s+/).filter(Boolean).length;
+    const byteCount = Buffer.byteLength(content, "utf-8");
+
+    totalLines += lineCount;
+    totalWords += wordCount;
+    totalBytes += byteCount;
+
+    let output = "";
+    if (showLines) output += `${lineCount.toString().padStart(8)}`;
+    if (showWords) output += `${wordCount.toString().padStart(8)}`;
+    if (showBytes) output += `${byteCount.toString().padStart(8)}`;
+    output += ` ${file}`;
+
+    console.log(output);
+  } catch (err) {
+    console.error(`Error reading file ${file}: ${err.message}`);
+  }
+}
+
+// If multiple files were given, show the total
+if (files.length > 1) {
+  let totalOutput = "";
+  if (showLines) totalOutput += `${totalLines.toString().padStart(8)}`;
+  if (showWords) totalOutput += `${totalWords.toString().padStart(8)}`;
+  if (showBytes) totalOutput += `${totalBytes.toString().padStart(8)}`;
+  totalOutput += " total";
+
+  console.log(totalOutput);
+}

implement-shell-tools/wc/package.json

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+{
+  "name": "wc",
+  "version": "1.0.0",
+  "description": "You should already be familiar with the `wc` command line tool.",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "commander": "^14.0.0"
+  }
+}