From 1576d23673c905182f65c30e60b937f6f83676b6 Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Sat, 21 Mar 2026 12:22:03 +0000
Subject: [PATCH 1/7] complete cat excercise

---
 implement-shell-tools/cat/cat.js | 60 ++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100755 implement-shell-tools/cat/cat.js

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
new file mode 100755
index 000000000..5005eed7e
--- /dev/null
+++ b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,60 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const path = require('path');
+
+function cat(files, options) {
+  let lineNumber = 1;
+
+  files.forEach((file) => {
+    const filePath = path.resolve(file);
+
+    try {
+      const data = fs.readFileSync(filePath, '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);
+        }
+      });
+    } catch (err) {
+      console.error(`cat: ${file}: No such file or directory`);
+    }
+  });
+}
+
+function main() {
+  const args = process.argv.slice(2);
+  const options = {
+    numberLines: false,
+    numberNonEmpty: false,
+  };
+
+  const files = [];
+
+  args.forEach((arg) => {
+    if (arg === '-n') {
+      options.numberLines = true;
+    } else if (arg === '-b') {
+      options.numberNonEmpty = true;
+    } else {
+      files.push(arg);
+    }
+  });
+
+  if (files.length === 0) {
+    console.error('Usage: node cat.js [-n | -b] <file>...');
+    process.exit(1);
+  }
+
+  cat(files, options);
+}
+
+main();
\ No newline at end of file

From 34fe1d09e26f469a2df3c27364a6d37b4aff91b3 Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Sat, 21 Mar 2026 12:43:06 +0000
Subject: [PATCH 2/7] complete ls exercise

---
 implement-shell-tools/ls/ls.js | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 implement-shell-tools/ls/ls.js

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
new file mode 100644
index 000000000..056213466
--- /dev/null
+++ b/implement-shell-tools/ls/ls.js
@@ -0,0 +1,44 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const path = require('path');
+
+function listFiles(directory, options) {
+  try {
+    const files = fs.readdirSync(directory, { withFileTypes: true });
+
+    files.forEach((file) => {
+      if (!options.all && file.name.startsWith('.')) {
+        return; // Skip hidden files unless -a is specified
+      }
+      console.log(file.name);
+    });
+  } catch (err) {
+    console.error(`ls: cannot access '${directory}': No such file or directory`);
+  }
+}
+
+function main() {
+  const args = process.argv.slice(2);
+  const options = {
+    all: false,
+  };
+
+  let 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.forEach((directory) => {
+    listFiles(directory, options);
+  });
+}
+
+main();
\ No newline at end of file

From daac5ecd310b8071a20a65a51ade077651e945fb Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Sat, 21 Mar 2026 13:19:53 +0000
Subject: [PATCH 3/7] complete wc exercise

---
 implement-shell-tools/wc/wc.js | 61 ++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 implement-shell-tools/wc/wc.js

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
new file mode 100644
index 000000000..60171cf31
--- /dev/null
+++ b/implement-shell-tools/wc/wc.js
@@ -0,0 +1,61 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const path = require('path');
+
+function countFile(filePath, options) {
+  try {
+    const data = fs.readFileSync(filePath, '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}`);
+    }
+  } catch (err) {
+    console.error(`wc: ${filePath}: No such file or directory`);
+  }
+}
+
+function main() {
+  const args = process.argv.slice(2);
+  const options = {
+    lines: false,
+    words: false,
+    bytes: false,
+  };
+
+  const files = [];
+
+  args.forEach((arg) => {
+    if (arg === '-l') {
+      options.lines = true;
+    } else if (arg === '-w') {
+      options.words = true;
+    } else if (arg === '-c') {
+      options.bytes = true;
+    } else {
+      files.push(arg);
+    }
+  });
+
+  if (files.length === 0) {
+    console.error('Usage: wc [-l | -w | -c] <file>...');
+    process.exit(1);
+  }
+
+  files.forEach((file) => {
+    const filePath = path.resolve(file);
+    countFile(filePath, options);
+  });
+}
+
+main();
\ No newline at end of file

From 7e70d1cc7d2a35a990362b4025ab7a3471167bb8 Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Sun, 5 Apr 2026 21:56:25 +0100
Subject: [PATCH 4/7] Refactor file handling and error messages in cat, ls, and
 wc tools

---
 implement-shell-tools/cat/cat.js | 25 ++++++++++++-------------
 implement-shell-tools/ls/ls.js   | 14 +++++++++-----
 implement-shell-tools/wc/wc.js   | 26 +++++++++++---------------
 3 files changed, 32 insertions(+), 33 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 5005eed7e..287b29148 100755
--- a/implement-shell-tools/cat/cat.js
+++ b/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);
     }
   });
 }
diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 056213466..b2587e30d 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/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);
   }
 }
 
@@ -24,7 +24,7 @@ function main() {
     all: false,
   };
 
-  let directories = ['.'];
+  const directories = [];
 
   args.forEach((arg) => {
     if (arg === '-1') {
@@ -32,10 +32,14 @@ function main() {
     } 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);
   });
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 60171cf31..e807112ce 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/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);
   });
 }
 

From a3dc8ae4141ef0ba56bc36a1ae406bc25615ce5c Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Fri, 10 Apr 2026 22:38:57 +0100
Subject: [PATCH 5/7] Enhance cat and wc tools: improve line numbering logic
 and aggregate results

---
 implement-shell-tools/cat/cat.js |  7 ++++++-
 implement-shell-tools/wc/wc.js   | 26 ++++++++++++++++++++++----
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 287b29148..eb092f348 100755
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -12,7 +12,12 @@ function cat(files, options) {
       const lines = data.split('\n');
 
       lines.forEach((line) => {
-        const prefix = options.numberNonEmpty && line.trim() ? `${lineNumber}\t` : options.numberLines ? `${lineNumber}\t` : '';
+        let prefix = '';
+        if (options.numberNonEmpty && line.trim()) {
+          prefix = `${lineNumber}\t`;
+        } else if (options.numberLines) {
+          prefix = `${lineNumber}\t`;
+        }
         console.log(`${prefix}${line}`);
         if (prefix) lineNumber++;
       });
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index e807112ce..d8f274665 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -11,11 +11,13 @@ function countFile(file, options) {
     const bytes = Buffer.byteLength(data, 'utf8');
 
     const results = [];
-    if (options.lines) results.push(lines);
-    if (options.words) results.push(words);
-    if (options.bytes) results.push(bytes);
+    if (options.lines || (!options.lines && !options.words && !options.bytes)) results.push(lines);
+    if (options.words || (!options.lines && !options.words && !options.bytes)) results.push(words);
+    if (options.bytes || (!options.lines && !options.words && !options.bytes)) results.push(bytes);
 
     console.log(`${results.join('\t')}\t${file}`);
+
+    return { lines, words, bytes };
   } catch (err) {
     console.error(`wc: ${file}: ${err.code === 'ENOENT' ? 'No such file or directory' : 'An error occurred'}`);
     process.exit(1);
@@ -49,9 +51,25 @@ function main() {
     process.exit(1);
   }
 
+  let totalLines = 0;
+  let totalWords = 0;
+  let totalBytes = 0;
+
   files.forEach((file) => {
-    countFile(file, options);
+    const { lines, words, bytes } = countFile(file, options);
+    totalLines += lines;
+    totalWords += words;
+    totalBytes += bytes;
   });
+
+  if (files.length > 1) {
+    const totalResults = [];
+    if (options.lines || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalLines);
+    if (options.words || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalWords);
+    if (options.bytes || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalBytes);
+
+    console.log(`${totalResults.join('\t')}\ttotal`);
+  }
 }
 
 main();
\ No newline at end of file

From 9f4f7aa5da47da0cdd1cefec8bab8bea3cd3cbb8 Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Wed, 15 Apr 2026 22:57:08 +0100
Subject: [PATCH 6/7] Refactor cat and wc tools: improve line handling and
 output formatting

---
 implement-shell-tools/cat/cat.js | 22 +++++++----
 implement-shell-tools/wc/wc.js   | 66 ++++++++++++++++++++++++--------
 2 files changed, 64 insertions(+), 24 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index eb092f348..855b51da7 100755
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -1,7 +1,6 @@
 #!/usr/bin/env node
 
 const fs = require('fs');
-const path = require('path');
 
 function cat(files, options) {
   let lineNumber = 1;
@@ -10,16 +9,23 @@ function cat(files, options) {
     try {
       const data = fs.readFileSync(file, 'utf8');
       const lines = data.split('\n');
+      const hasTrailingNewline = data.endsWith('\n');
+
+      lines.forEach((line, index) => {
+        const isVirtualTrailingLine = hasTrailingNewline && index === lines.length - 1;
+        if (isVirtualTrailingLine) {
+          return;
+        }
 
-      lines.forEach((line) => {
         let prefix = '';
-        if (options.numberNonEmpty && line.trim()) {
-          prefix = `${lineNumber}\t`;
-        } else if (options.numberLines) {
-          prefix = `${lineNumber}\t`;
+        const shouldNumberLine = options.numberLines || (options.numberNonEmpty && line.length > 0);
+        if (shouldNumberLine) {
+          prefix = `${String(lineNumber).padStart(6)}\t`;
+          lineNumber++;
         }
-        console.log(`${prefix}${line}`);
-        if (prefix) lineNumber++;
+
+        const shouldAppendNewline = hasTrailingNewline || index < lines.length - 1;
+        process.stdout.write(`${prefix}${line}${shouldAppendNewline ? '\n' : ''}`);
       });
     } catch (err) {
       if (err.code === 'ENOENT') {
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index d8f274665..4f4602e1b 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -2,21 +2,14 @@
 
 const fs = require('fs');
 
-function countFile(file, options) {
+function countFile(file) {
   try {
     const data = fs.readFileSync(file, 'utf8');
 
-    const lines = data.split('\n').length;
+    const lines = (data.match(/\n/g) || []).length;
     const words = data.split(/\s+/).filter(Boolean).length;
     const bytes = Buffer.byteLength(data, 'utf8');
 
-    const results = [];
-    if (options.lines || (!options.lines && !options.words && !options.bytes)) results.push(lines);
-    if (options.words || (!options.lines && !options.words && !options.bytes)) results.push(words);
-    if (options.bytes || (!options.lines && !options.words && !options.bytes)) results.push(bytes);
-
-    console.log(`${results.join('\t')}\t${file}`);
-
     return { lines, words, bytes };
   } catch (err) {
     console.error(`wc: ${file}: ${err.code === 'ENOENT' ? 'No such file or directory' : 'An error occurred'}`);
@@ -24,6 +17,40 @@ function countFile(file, options) {
   }
 }
 
+function selectedKeys(options) {
+  const keys = [];
+  if (options.lines) keys.push('lines');
+  if (options.words) keys.push('words');
+  if (options.bytes) keys.push('bytes');
+  return keys;
+}
+
+function valuesForKeys(counts, keys) {
+  return keys.map((key) => counts[key]);
+}
+
+function printRows(rows, keys) {
+  const alignColumns = keys.length > 1 || rows.length > 1;
+
+  if (!alignColumns) {
+    const [values, name] = rows[0];
+    console.log(`${values[0]} ${name}`);
+    return;
+  }
+
+  const widths = keys.map((_, index) => {
+    const maxLen = Math.max(...rows.map(([values]) => String(values[index]).length));
+    return Math.max(3, maxLen);
+  });
+
+  rows.forEach(([values, name]) => {
+    const formattedValues = values
+      .map((value, index) => String(value).padStart(widths[index], ' '))
+      .join(' ');
+    console.log(`${formattedValues} ${name}`);
+  });
+}
+
 function main() {
   const args = process.argv.slice(2);
   const options = {
@@ -46,6 +73,12 @@ function main() {
     }
   });
 
+  if (!options.lines && !options.words && !options.bytes) {
+    options.lines = true;
+    options.words = true;
+    options.bytes = true;
+  }
+
   if (files.length === 0) {
     console.error('Usage: wc [-l | -w | -c] <file>...');
     process.exit(1);
@@ -54,22 +87,23 @@ function main() {
   let totalLines = 0;
   let totalWords = 0;
   let totalBytes = 0;
+  const keys = selectedKeys(options);
+  const rows = [];
 
   files.forEach((file) => {
-    const { lines, words, bytes } = countFile(file, options);
+    const counts = countFile(file);
+    const { lines, words, bytes } = counts;
     totalLines += lines;
     totalWords += words;
     totalBytes += bytes;
+    rows.push([valuesForKeys(counts, keys), file]);
   });
 
   if (files.length > 1) {
-    const totalResults = [];
-    if (options.lines || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalLines);
-    if (options.words || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalWords);
-    if (options.bytes || (!options.lines && !options.words && !options.bytes)) totalResults.push(totalBytes);
-
-    console.log(`${totalResults.join('\t')}\ttotal`);
+    rows.push([valuesForKeys({ lines: totalLines, words: totalWords, bytes: totalBytes }, keys), 'total']);
   }
+
+  printRows(rows, keys);
 }
 
 main();
\ No newline at end of file

From 054db4143497707aed0d725c46264a78e7381252 Mon Sep 17 00:00:00 2001
From: enjoy15 <narumoljoy@gmail.com>
Date: Wed, 15 Apr 2026 22:58:05 +0100
Subject: [PATCH 7/7] Refactor cat tool: simplify line handling and improve
 output formatting

---
 implement-shell-tools/cat/cat.js | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 855b51da7..ed2360d49 100755
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -1,6 +1,7 @@
 #!/usr/bin/env node
 
 const fs = require('fs');
+const path = require('path');
 
 function cat(files, options) {
   let lineNumber = 1;
@@ -9,23 +10,15 @@ function cat(files, options) {
     try {
       const data = fs.readFileSync(file, 'utf8');
       const lines = data.split('\n');
-      const hasTrailingNewline = data.endsWith('\n');
-
-      lines.forEach((line, index) => {
-        const isVirtualTrailingLine = hasTrailingNewline && index === lines.length - 1;
-        if (isVirtualTrailingLine) {
-          return;
-        }
 
+      lines.forEach((line) => {
         let prefix = '';
-        const shouldNumberLine = options.numberLines || (options.numberNonEmpty && line.length > 0);
+        const shouldNumberLine = options.numberLines || (options.numberNonEmpty && line.trim());
         if (shouldNumberLine) {
-          prefix = `${String(lineNumber).padStart(6)}\t`;
+          prefix = `${lineNumber}\t`;
           lineNumber++;
         }
-
-        const shouldAppendNewline = hasTrailingNewline || index < lines.length - 1;
-        process.stdout.write(`${prefix}${line}${shouldAppendNewline ? '\n' : ''}`);
+        console.log(`${prefix}${line}`);
       });
     } catch (err) {
       if (err.code === 'ENOENT') {