Refactor file handling and error messages in cat, ls, and wc tools

Author: enjoy15

implement-shell-tools/cat/cat.js

@@ -7,25 +7,24 @@ function cat(files, options) {
   let lineNumber = 1;
 
   files.forEach((file) => {
-    const filePath = path.resolve(file);
-
     try {
-      const data = fs.readFileSync(filePath, 'utf8');
+      const data = fs.readFileSync(file, 'utf8');
       const lines = data.split('\n');
 
       lines.forEach((line) => {
-        if (options.numberNonEmpty && line.trim()) {
-          console.log(`${lineNumber}\t${line}`);
-          lineNumber++;
-        } else if (options.numberLines) {
-          console.log(`${lineNumber}\t${line}`);
-          lineNumber++;
-        } else {
-          console.log(line);
-        }
+        const prefix = options.numberNonEmpty && line.trim() ? `${lineNumber}\t` : options.numberLines ? `${lineNumber}\t` : '';
+        console.log(`${prefix}${line}`);
+        if (prefix) lineNumber++;
       });
     } catch (err) {
-      console.error(`cat: ${file}: No such file or directory`);
+      if (err.code === 'ENOENT') {
+        console.error(`cat: ${file}: No such file or directory`);
+      } else if (err.code === 'EACCES') {
+        console.error(`cat: ${file}: Permission denied`);
+      } else {
+        console.error(`cat: ${file}: An error occurred`);
+      }
+      process.exit(1);
     }
   });
 }

implement-shell-tools/ls/ls.js

@@ -1,7 +1,6 @@
 #!/usr/bin/env node
 
 const fs = require('fs');
-const path = require('path');
 
 function listFiles(directory, options) {
   try {
@@ -11,10 +10,11 @@ function listFiles(directory, options) {
       if (!options.all && file.name.startsWith('.')) {
         return; // Skip hidden files unless -a is specified
       }
-      console.log(file.name);
+      console.log(`${directory}/${file.name}`);
     });
   } catch (err) {
-    console.error(`ls: cannot access '${directory}': No such file or directory`);
+    console.error(`ls: cannot access '${directory}': ${err.code === 'ENOENT' ? 'No such file or directory' : 'An error occurred'}`);
+    process.exit(1);
   }
 }
 
@@ -24,18 +24,22 @@ function main() {
     all: false,
   };
 
-  let directories = ['.'];
+  const directories = [];
 
   args.forEach((arg) => {
     if (arg === '-1') {
       // -1 is the default behavior, so no action needed
     } else if (arg === '-a') {
       options.all = true;
     } else {
-      directories = [arg];
+      directories.push(arg);
     }
   });
 
+  if (directories.length === 0) {
+    directories.push('.');
+  }
+
   directories.forEach((directory) => {
     listFiles(directory, options);
   });

implement-shell-tools/wc/wc.js

@@ -1,27 +1,24 @@
 #!/usr/bin/env node
 
 const fs = require('fs');
-const path = require('path');
 
-function countFile(filePath, options) {
+function countFile(file, options) {
   try {
-    const data = fs.readFileSync(filePath, 'utf8');
+    const data = fs.readFileSync(file, 'utf8');
 
     const lines = data.split('\n').length;
     const words = data.split(/\s+/).filter(Boolean).length;
     const bytes = Buffer.byteLength(data, 'utf8');
 
-    if (options.lines) {
-      console.log(`${lines}\t${filePath}`);
-    } else if (options.words) {
-      console.log(`${words}\t${filePath}`);
-    } else if (options.bytes) {
-      console.log(`${bytes}\t${filePath}`);
-    } else {
-      console.log(`${lines}\t${words}\t${bytes}\t${filePath}`);
-    }
+    const results = [];
+    if (options.lines) results.push(lines);
+    if (options.words) results.push(words);
+    if (options.bytes) results.push(bytes);
+
+    console.log(`${results.join('\t')}\t${file}`);
   } catch (err) {
-    console.error(`wc: ${filePath}: No such file or directory`);
+    console.error(`wc: ${file}: ${err.code === 'ENOENT' ? 'No such file or directory' : 'An error occurred'}`);
+    process.exit(1);
   }
 }
 
@@ -53,8 +50,7 @@ function main() {
   }
 
   files.forEach((file) => {
-    const filePath = path.resolve(file);
-    countFile(filePath, options);
+    countFile(file, options);
   });
 }