London | 25-SDC-Nov | Zohreh Kazemianpour | Sprint 3 | Implement Shell Tools-NodeJS

.gitignore

@@ -1 +1,4 @@
+
+prep
 node_modules
+.venv

implement-shell-tools/.gitignore

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+prep/
+prep/

implement-shell-tools/cat/cat.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+//here we Configure the program: what flags and arguments it accepts
+// .option("short, long", "description")
+//The < > brackets mean "required"
+
+program
+  .name("cat")
+  .description("concatenate and print files")
+  .option("-n, --number", "Number all output lines")
+  .option("-b, --numberNonBlank", "Number non-blank output lines")
+  .argument("<path...>", "The file paths to process");
+
+// here Parse command line arguments (reads process.argv and interprets it)
+program.parse();
+
+// Shared counter across all files for -n and -b flags
+let lineNumber = 0;
+
+
+// Process each file
+for (const path of program.args) {
+  const hasNumberFlag = program.opts().number; // True if user used -n flag
+  const shouldNumberNonBlank = program.opts().numberNonBlank;
+
+  //read the file for each argument
+  const content = await fs.readFile(path, "utf-8");
+  const lines = content.split("\n"); // Split into array of lines
+
+  // Output with or without line numbers
+  if (hasNumberFlag) {
+    // Add line numbers to each line
+    const numberedLines = lines.map((line) => {
+      lineNumber = lineNumber + 1;
+      return `${lineNumber} ${line}`; // Format: "     1  Hello"
+    });
+    console.log(numberedLines.join("\n")); // Join back with newlines
+  } else if (shouldNumberNonBlank) {
+
+    const numberedLines = lines.map((line) => {
+      return line.trim() === "" ? line : `${++lineNumber} ${line}`;
+    });
+    console.log(numberedLines.join("\n"));
+  } else {
+    // Just print the file as-is
+    console.log(content);
+  }
+}
+

implement-shell-tools/ls/ls.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+//config the program
+program
+  .name("ls")
+  .description("list directory contents")
+  .option("-1, --one", "Force output to be one entry per line")
+  .option(
+    "-a, --all",
+    "shows all the files including the hidden ones which start with a dot"
+  )
+  .argument("[directory]", "Directory to list", "."); // "." means current directory
+
+//interpret the program
+program.parse();
+
+// Get the directory argument (first argument in program.args array)
+// If no argument provided, default to current directory "."
+const directory = program.args[0] || ".";
+
+//read the directory to get array of filenames
+const files = await fs.readdir(directory);
+
+//check for flags
+const hasAflag = program.opts().all;
+const hasOneFlag = program.opts().one;
+
+// Filter the files array BEFORE looping
+// If hasAflag is true, keep all files
+// If hasAflag is false, remove files that start with "."
+
+const fileToShow = hasAflag 
+? files
+: files.filter(file => !file.startsWith("."))
+
+
+if (hasOneFlag) {
+
+  for (const file of fileToShow) {
+    console.log(file);
+  }
+} else {
+  // print horizontally 
+  console.log(fileToShow.join("  "));
+}
+

implement-shell-tools/package.json

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+{
+  "type": "module"
+}

implement-shell-tools/wc/wc.js

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+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+//config the program
+program
+  .name("wc")
+  .description(
+    "The wc utility displays the number of lines, words, and bytes contained in each input file, or standard input"
+  )
+  .option("-l, --lines", "count lines only")
+  .option("-w, --words", "count words only")
+  .option("-c, --bytes", "count bytes only")
+  .argument("<path...>", "The file paths to process");
+
+//interpret the program
+program.parse();
+
+//initialise totals
+let totalLines = 0;
+let totalWords = 0;
+let totalBytes = 0;
+
+//check for flags
+const hasLineFlag = program.opts().lines;
+const hasWordFlag = program.opts().words;
+const hasBytesFlag = program.opts().bytes;
+
+// create output format function to avoid repetition
+function formatOutput(lines, words, bytes, path) {
+  if (hasLineFlag) {
+    console.log(`${lines} ${path}`);
+  } else if (hasWordFlag) {
+    console.log(`${words} ${path}`);
+  } else if (hasBytesFlag) {
+    console.log(`${bytes} ${path}`);
+  } else {
+    console.log(`${lines} ${words} ${bytes} ${path}`);
+  }
+}
+
+//process each file
+
+for (const path of program.args) {
+  //read the file
+  const content = await fs.readFile(path, "utf-8");
+
+  //count lines
+  const lines = content.split("\n").length - 1;
+
+  //count words (split by any whitespace)
+  const words = content.split(/\s+/).filter((word) => word.length > 0).length;
+
+  //count bytes correctly especially important for non-ASCII characters
+  const bytes = Buffer.byteLength(content, "utf-8");
+
+  //Add to totals
+  totalLines += lines;
+  totalWords += words;
+  totalBytes += bytes;
+
+  formatOutput(lines, words, bytes, path);
+}
+
+if (program.args.length > 1) {
+  formatOutput(totalLines, totalWords, totalBytes, "total");
+}

package.json

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+{
+  "type": "module",
+  "dependencies": {
+    "commander": "^14.0.2"
+  }
+}