London | 26-JUL-SDC | Ping Wang | Sprint 3 | Implement- shell- tools

implement-shell-tools/cat/cat.js

@@ -0,0 +1,33 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+const numberAll = args[0] === "-n";
+const numberNonBlank = args[0] === "-b";
+
+const files = (numberAll || numberNonBlank)
+  ? args.slice(1)
+  : args;
+
+let lineNumber = 1;
+
+for (const file of files) {
+  const content = fs.readFileSync(file, "utf8");
+  const lines = content.split("\n");
+
+  for (const line of lines) {
+
+    if (numberAll) {
+      console.log(`${String(lineNumber).padStart(6)}\t${line}`);
+      lineNumber++;
+
+    } else if (numberNonBlank && line !== "") {
+      console.log(`${String(lineNumber).padStart(6)}\t${line}`);
+      lineNumber++;
+
+    } else {
+      console.log(line);
+    }
+
+  }
+}

implement-shell-tools/ls/ls.js

@@ -0,0 +1,56 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+let oneLine = false;
+let showHidden = false;
+let targets = [];
+
+for (const arg of args) {
+    if (arg === "-1") {
+        oneLine = true;
+    } else if (arg === "-a") {
+        showHidden = true;
+    } else {
+        targets.push(arg);
+    }
+}
+
+if (targets.length === 0) {
+    targets.push(".");
+}
+
+function listDirectory(directory) {
+    let files = fs.readdirSync(directory);
+
+    if (!showHidden) {
+        files = files.filter(file => !file.startsWith("."));
+    }
+
+    files.sort();
+
+    if (oneLine) {
+        console.log(files.join("\n"));
+    } else {
+        console.log(files.join("  "));
+    }
+}
+
+function listTarget(target) {
+    try {
+        const stats = fs.statSync(target);
+
+        if (stats.isDirectory()) {
+            listDirectory(target);
+        } else {
+            console.log(target);
+        }
+
+    } catch (error) {
+        console.error(`ls: cannot access '${target}': No such file or directory`);
+    }
+}
+
+for (const target of targets) {
+    listTarget(target);
+}

implement-shell-tools/wc/wc.js

@@ -0,0 +1,57 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+let countLines = false;
+let countWords = false;
+let countBytes = false;
+let files = [];
+
+for (const arg of args) {
+    if (arg === "-l") {
+        countLines = true;
+    } else if (arg === "-w") {
+        countWords = true;
+    } else if (arg === "-c") {
+        countBytes = true;
+    } else {
+        files.push(arg);
+    }
+}
+
+// If no flags are given, wc shows all three
+if (!countLines && !countWords && !countBytes) {
+    countLines = true;
+    countWords = true;
+    countBytes = true;
+}
+
+function countFile(filename) {
+    const content = fs.readFileSync(filename, "utf8");
+
+    const lines = content.split("\n").length - 1;
+    const words = content.trim() === "" ? 0 : content.trim().split(/\s+/).length;
+    const bytes = Buffer.byteLength(content);
+
+    let output = [];
+
+    if (countLines) {
+        output.push(lines);
+    }
+
+    if (countWords) {
+        output.push(words);
+    }
+
+    if (countBytes) {
+        output.push(bytes);
+    }
+
+    output.push(filename);
+
+    console.log(output.join(" "));
+}
+
+for (const file of files) {
+    countFile(file);
+}