From de68e2e88b8cd4a1fe2f3d114482c3e31d37a6d1 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 11:17:38 +0000
Subject: [PATCH 01/11] Implementing cat with process.argv-node feature to
 access what user types in terminal.

---
 implement-shell-tools/cat/cat.js | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 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 100644
index 00000000..cb19a15a
--- /dev/null
+++ b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,13 @@
+import process from "node:process"
+import {promises as fs} from "node:fs"
+
+
+const argv = process.argv.slice(2)
+if (argv.length != 1) {
+  console.error(`Expected exactly 1 argument (a path) to be passed but got ${argv.length}.`);
+  process.exit(1);
+}
+
+const path = argv[0]
+const content = await fs.readFile(path, "utf-8")
+console.log(content)

From fdbd244648d35aea74721f2edc89c76cfb5454f4 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 14:42:06 +0000
Subject: [PATCH 02/11] Adding gitignore and package.json for installing
 dependencies

---
 implement-shell-tools/.gitignore   | 5 +++++
 implement-shell-tools/package.json | 6 ++++++
 2 files changed, 11 insertions(+)
 create mode 100644 implement-shell-tools/.gitignore
 create mode 100644 implement-shell-tools/package.json

diff --git a/implement-shell-tools/.gitignore b/implement-shell-tools/.gitignore
new file mode 100644
index 00000000..84e210b2
--- /dev/null
+++ b/implement-shell-tools/.gitignore
@@ -0,0 +1,5 @@
+# Node modules
+node_modules/
+
+# Package lock file (optional)
+package-lock.json
\ No newline at end of file
diff --git a/implement-shell-tools/package.json b/implement-shell-tools/package.json
new file mode 100644
index 00000000..aff57833
--- /dev/null
+++ b/implement-shell-tools/package.json
@@ -0,0 +1,6 @@
+{
+    "type": "module",
+    "dependencies": {
+        "commander": "^14.0.2"
+    }
+}

From 007ee5411e94cf2b19fca906170e190c0ec5e780 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 14:42:52 +0000
Subject: [PATCH 03/11] Adding implementation to count number of lines

---
 implement-shell-tools/cat/cat.js   | 13 ----------
 implement-shell-tools/cat/mycat.js | 38 ++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 13 deletions(-)
 delete mode 100644 implement-shell-tools/cat/cat.js
 create mode 100644 implement-shell-tools/cat/mycat.js

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
deleted file mode 100644
index cb19a15a..00000000
--- a/implement-shell-tools/cat/cat.js
+++ /dev/null
@@ -1,13 +0,0 @@
-import process from "node:process"
-import {promises as fs} from "node:fs"
-
-
-const argv = process.argv.slice(2)
-if (argv.length != 1) {
-  console.error(`Expected exactly 1 argument (a path) to be passed but got ${argv.length}.`);
-  process.exit(1);
-}
-
-const path = argv[0]
-const content = await fs.readFile(path, "utf-8")
-console.log(content)
diff --git a/implement-shell-tools/cat/mycat.js b/implement-shell-tools/cat/mycat.js
new file mode 100644
index 00000000..4a1de3d1
--- /dev/null
+++ b/implement-shell-tools/cat/mycat.js
@@ -0,0 +1,38 @@
+import { program } from "commander";
+import {promises as fs} from "node:fs"
+
+
+
+ //configuring the program here to run flags.
+
+program
+  .name("cat")
+  .description("Concatenate and print files")
+  .option("-n, --number", "Number all output lines")
+  .option("-b, --number-nonblank", "Number non-blank output lines") 
+  .argument("<files...>", "File paths to display")
+  .parse(process.argv);//Parse command line arguments (reads process.argv and interprets it)
+  
+const options = program.opts(); 
+const files = program.args; // Array of file paths passed as arguments
+
+let lineNumber = 1; // shared across all files, like GNU cat -n)
+
+for (const file of files) {
+  const content = await fs.readFile(file, "utf-8"); 
+  const lines = content.split("\n");
+
+  for (const line of lines) {
+   
+    if (options.number) {
+      console.log(`${lineNumber.toString().padStart(6)}  ${line}`); // adding padding for formatting 
+      lineNumber++;
+    }  
+    else{
+      console.log(line);  
+    } 
+    }
+  }
+
+
+

From 56e274077d0187d6f6e0195bcb217ef652383895 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 14:59:54 +0000
Subject: [PATCH 04/11] Adding implementation for the b flag

---
 implement-shell-tools/cat/{mycat.js => file.js} | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
 rename implement-shell-tools/cat/{mycat.js => file.js} (81%)

diff --git a/implement-shell-tools/cat/mycat.js b/implement-shell-tools/cat/file.js
similarity index 81%
rename from implement-shell-tools/cat/mycat.js
rename to implement-shell-tools/cat/file.js
index 4a1de3d1..f578048e 100644
--- a/implement-shell-tools/cat/mycat.js
+++ b/implement-shell-tools/cat/file.js
@@ -28,7 +28,14 @@ for (const file of files) {
       console.log(`${lineNumber.toString().padStart(6)}  ${line}`); // adding padding for formatting 
       lineNumber++;
     }  
-    else{
+    else if (options.numberNonblank) { // -b
+      if (line.trim() === "") {
+        console.log(line);
+      } else {
+        console.log(`${lineNumber.toString().padStart(6)}  ${line}`);
+        lineNumber++;
+      }
+    } else {
       console.log(line);  
     } 
     }

From 1bcd51349e7ba2cf54b01f28c44c17bea4c04560 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 15:36:08 +0000
Subject: [PATCH 05/11] implementation for ls -1 flag.

---
 implement-shell-tools/ls/ls.js | 23 +++++++++++++++++++++++
 1 file changed, 23 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 00000000..2f5cce05
--- /dev/null
+++ b/implement-shell-tools/ls/ls.js
@@ -0,0 +1,23 @@
+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+//configuring 
+program
+  .name("ls")
+  .description("list directory contents")
+  .option("-1, --one", "Outputs are printed one entry per line")
+  .argument("[directory]", "Directory to list", "."); // "." means current directory
+
+//interpret the program
+program.parse();
+const directory = program.args[0] || "."; //get dir arg- 1st arg in program.args array || if no arg default to current dir
+
+
+const files = await fs.readdir(directory); //read the dir to get array of filenames
+
+
+
+//print each file on its own line
+for (const file of files) { // Loop prints each individually on separate lines
+    console.log(file)
+}
\ No newline at end of file

From e44078e4a105e024fb55f2d2ecd9b731d35d0794 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Fri, 21 Nov 2025 15:56:14 +0000
Subject: [PATCH 06/11] Adding implementation for -a flag

---
 implement-shell-tools/ls/ls.js | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 2f5cce05..fa854d4a 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -6,18 +6,27 @@ program
   .name("ls")
   .description("list directory contents")
   .option("-1, --one", "Outputs are printed one entry per line")
+  .option("-a, --all","Show all files including hidden files that start with a .")
   .argument("[directory]", "Directory to list", "."); // "." means current directory
 
 //interpret the program
 program.parse();
+const options = program.opts();
 const directory = program.args[0] || "."; //get dir arg- 1st arg in program.args array || if no arg default to current dir
 
 
-const files = await fs.readdir(directory); //read the dir to get array of filenames
+let files = await fs.readdir(directory); //read the dir to get array of filenames
 
 
+if (!options.all) { //Handle -a (include hidden files)
+  files = files.filter(name => !name.startsWith("."));
+}
 
-//print each file on its own line
-for (const file of files) { // Loop prints each individually on separate lines
-    console.log(file)
+if (options.one) { // Print each file on its own line
+  for (const file of files) {
+    console.log(file);
+  }
+}
+else {
+  console.log(files.join(" "));// Default: join with spaces (like ls without -1)
 }
\ No newline at end of file

From 99aae232176cf4eee4deaf9d3f64ff99942d6355 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Sat, 22 Nov 2025 20:00:53 +0000
Subject: [PATCH 07/11] Refactoring code with helper functions and removing
 trailing extra lines.

---
 implement-shell-tools/cat/file.js | 53 +++++++++++++++++++------------
 1 file changed, 32 insertions(+), 21 deletions(-)

diff --git a/implement-shell-tools/cat/file.js b/implement-shell-tools/cat/file.js
index f578048e..53f9adb5 100644
--- a/implement-shell-tools/cat/file.js
+++ b/implement-shell-tools/cat/file.js
@@ -1,8 +1,9 @@
+//On macOS (BSD cat), the -n option resets numbering for each file, so multiple files start again at 1,
+//when you run cat -n sample-files/*.txt
+//This Node.js script mimics GNU cat, where -n continues numbering across all files instead of restarting.
 import { program } from "commander";
 import {promises as fs} from "node:fs"
 
-
-
  //configuring the program here to run flags.
 
 program
@@ -13,33 +14,43 @@ program
   .argument("<files...>", "File paths to display")
   .parse(process.argv);//Parse command line arguments (reads process.argv and interprets it)
   
+
+//Constants
+const paddingWidth = 6; // width for line number padding
+
+// Helper function to format a line with numbering
+function formatLine(line, lineNumber, numberAll, numberNonBlank) {
+  if (numberAll) {
+    return `${lineNumber.toString().padStart(paddingWidth)}  ${line}`;
+  }
+  if (numberNonBlank) {
+    if (line.trim() === "") {
+      return line; // blank line, no number
+    }
+    return `${lineNumber.toString().padStart(paddingWidth)}  ${line}`;
+  }
+  return line; // no numbering
+}
 const options = program.opts(); 
 const files = program.args; // Array of file paths passed as arguments
 
-let lineNumber = 1; // shared across all files, like GNU cat -n)
+let lineNumber = 1; // shared across all files
 
 for (const file of files) {
   const content = await fs.readFile(file, "utf-8"); 
-  const lines = content.split("\n");
+  let lines = content.split("\n");
+  // Remove trailing empty line if file ends with newline
+  if (lines.length > 0 && lines[lines.length - 1] === "") {
+    lines.pop();
+  }
 
   for (const line of lines) {
-   
-    if (options.number) {
-      console.log(`${lineNumber.toString().padStart(6)}  ${line}`); // adding padding for formatting 
+    const formatted = formatLine(line, lineNumber, options.number, options.numberNonblank);
+    console.log(formatted);
+
+    // Increment line number if numbering applies
+    if (options.number || (options.numberNonblank && line.trim() !== "")) {
       lineNumber++;
-    }  
-    else if (options.numberNonblank) { // -b
-      if (line.trim() === "") {
-        console.log(line);
-      } else {
-        console.log(`${lineNumber.toString().padStart(6)}  ${line}`);
-        lineNumber++;
-      }
-    } else {
-      console.log(line);  
-    } 
     }
   }
-
-
-
+}
\ No newline at end of file

From e8c2041bff412e264365d2d312a0b872dbd86d99 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Sat, 22 Nov 2025 20:07:35 +0000
Subject: [PATCH 08/11] node implementation for wc

---
 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 00000000..339afa50
--- /dev/null
+++ b/implement-shell-tools/wc/wc.js
@@ -0,0 +1,61 @@
+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+//configuring 
+program
+  .name("wc")
+  .description("Print newline, word, and byte counts for each file")
+  .option("-l, --lines", "Print the newline counts")
+  .option("-w, --words", "Print the word counts")
+  .option("-c, --bytes", "Print the byte counts")
+  .argument("<files...>", "File paths to process")
+//Interpret the program
+  program.parse()
+const options = program.opts()
+const files = program.args //Interpreting parsed data
+
+
+//helper function to calculate all counts 
+async function getCounts(file){
+  const content = await fs.readFile(file, "utf-8");
+  const lineCount = content.split("\n").length -1;//split("\n") returns one more element than the actual number so length-1,
+  const wordCount = content.trim().split(/\s+/).length;
+  const byteCount = Buffer.byteLength(content, "utf-8"); //Calculate how many bytes the string uses in UTF-8 (important because some characters use more than 1 byte)
+  return { lineCount, wordCount, byteCount };
+}
+//initiating totals
+let totalLines = 0;
+let totalWords = 0;
+let totalBytes = 0;
+
+for (const file of files) {
+  const { lineCount, wordCount, byteCount } = await getCounts(file);
+
+  totalLines += lineCount;
+  totalWords += wordCount;
+  totalBytes += byteCount;
+
+let output = "";
+  if (options.lines) output += `${lineCount} `;
+  if (options.words) output += `${wordCount} `;
+  if (options.bytes) output += `${byteCount} `;
+  if (!options.lines && !options.words && !options.bytes) {
+    output += `${lineCount} ${wordCount} ${byteCount} `;
+  }
+  output += file;
+  console.log(output);
+}
+  
+  
+  //Print totals if multiple files
+if (files.length > 1) {
+  let totalOutput = "";
+  if (options.lines) totalOutput += `${totalLines} `;
+  if (options.words) totalOutput += `${totalWords} `;
+  if (options.bytes) totalOutput += `${totalBytes} `;
+  if (!options.lines && !options.words && !options.bytes) {
+    totalOutput += `${totalLines} ${totalWords} ${totalBytes} `;
+  }
+  totalOutput += "total";
+  console.log(totalOutput);
+}
\ No newline at end of file

From 6152444ac953558ae15468006013d0d414a2605d Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Sat, 22 Nov 2025 20:23:07 +0000
Subject: [PATCH 09/11] Fix -a flag handling to include current and parent dir
 while running with node to mimic ls

---
 implement-shell-tools/ls/ls.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index fa854d4a..449835ae 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -17,8 +17,15 @@ const directory = program.args[0] || "."; //get dir arg- 1st arg in program.args
 
 let files = await fs.readdir(directory); //read the dir to get array of filenames
 
-
-if (!options.all) { //Handle -a (include hidden files)
+//Handle -a (include hidden files)
+// Node's fs.readdir() does not include the special directory entries "." (current dir)
+// and ".." (parent dir). The real `ls -a` command shows them, so we add them manually here
+// to match the behavior of `ls -a`.
+if (options.all) { 
+  
+  files.unshift(".."); 
+  files.unshift(".");
+} else {
   files = files.filter(name => !name.startsWith("."));
 }
 

From 9463024ea0babc2a563bc1ea7e2c4e855738ffc1 Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Sun, 21 Dec 2025 21:23:28 +0000
Subject: [PATCH 10/11] Removed the duplicated code for line formatting

---
 implement-shell-tools/cat/file.js | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/implement-shell-tools/cat/file.js b/implement-shell-tools/cat/file.js
index 53f9adb5..15490496 100644
--- a/implement-shell-tools/cat/file.js
+++ b/implement-shell-tools/cat/file.js
@@ -20,17 +20,15 @@ const paddingWidth = 6; // width for line number padding
 
 // Helper function to format a line with numbering
 function formatLine(line, lineNumber, numberAll, numberNonBlank) {
+  const numbered =`${lineNumber.toString().padStart(paddingWidth)}  ${line}`;
   if (numberAll) {
-    return `${lineNumber.toString().padStart(paddingWidth)}  ${line}`;
+    return numbered
   }
-  if (numberNonBlank) {
-    if (line.trim() === "") {
-      return line; // blank line, no number
-    }
-    return `${lineNumber.toString().padStart(paddingWidth)}  ${line}`;
-  }
-  return line; // no numbering
-}
+  if (numberNonBlank) { 
+    return line.trim() === "" ? line : numbered; 
+  } 
+  return line;
+ }
 const options = program.opts(); 
 const files = program.args; // Array of file paths passed as arguments
 

From 3de99680a5b684b97497b96106303ff15115134a Mon Sep 17 00:00:00 2001
From: Sara Tahir <saratahir34@gmail.com>
Date: Sun, 21 Dec 2025 21:49:17 +0000
Subject: [PATCH 11/11] Removing duplication of output code with a helper
 function.

---
 implement-shell-tools/wc/wc.js | 46 +++++++++++++++++-----------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 339afa50..fda14b91 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -23,7 +23,18 @@ async function getCounts(file){
   const byteCount = Buffer.byteLength(content, "utf-8"); //Calculate how many bytes the string uses in UTF-8 (important because some characters use more than 1 byte)
   return { lineCount, wordCount, byteCount };
 }
-//initiating totals
+//helper to remove duplicated output logic 
+function formatOutput(lines, words, bytes, filename, options) {
+   let formattedOutput = ""; 
+   if (options.lines) formattedOutput += `${lines} `; 
+   if (options.words) formattedOutput+= `${words} `; 
+   if (options.bytes) formattedOutput += `${bytes} `; 
+   if (!options.lines && !options.words && !options.bytes) { // default: print all three 
+     formattedOutput += `${lines} ${words} ${bytes} `; 
+    }
+    return formattedOutput + filename; 
+  }
+ //Initiating totals
 let totalLines = 0;
 let totalWords = 0;
 let totalBytes = 0;
@@ -35,27 +46,16 @@ for (const file of files) {
   totalWords += wordCount;
   totalBytes += byteCount;
 
-let output = "";
-  if (options.lines) output += `${lineCount} `;
-  if (options.words) output += `${wordCount} `;
-  if (options.bytes) output += `${byteCount} `;
-  if (!options.lines && !options.words && !options.bytes) {
-    output += `${lineCount} ${wordCount} ${byteCount} `;
-  }
-  output += file;
-  console.log(output);
+  const formatted = formatOutput(lineCount, wordCount, byteCount, file, options);
+  console.log(formatted);
 }
-  
-  
-  //Print totals if multiple files
+//Print totals if multiple files
 if (files.length > 1) {
-  let totalOutput = "";
-  if (options.lines) totalOutput += `${totalLines} `;
-  if (options.words) totalOutput += `${totalWords} `;
-  if (options.bytes) totalOutput += `${totalBytes} `;
-  if (!options.lines && !options.words && !options.bytes) {
-    totalOutput += `${totalLines} ${totalWords} ${totalBytes} `;
-  }
-  totalOutput += "total";
-  console.log(totalOutput);
-}
\ No newline at end of file
+  const formattedTotals = formatOutput(totalLines, totalWords, totalBytes, "total", options);
+  console.log(formattedTotals);
+}
+
+
+
+
+  
\ No newline at end of file