From 04e0f692fd379c5029029b63a2c7d8bc79846139 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Tue, 21 Jul 2026 21:01:38 +0100
Subject: [PATCH 01/22] cat initial implementation

---
 implement-shell-tools/cat/cat.js       | 16 ++++++++++++++++
 implement-shell-tools/cat/package.json | 13 +++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 implement-shell-tools/cat/cat.js
 create mode 100644 implement-shell-tools/cat/package.json

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
new file mode 100644
index 000000000..032e8a475
--- /dev/null
+++ b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,16 @@
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+const path = process.argv.slice(2)[0];
+const numLines = process.argv.slice(3)[0];
+
+// console.log(numLines);
+// console.log(process.argv.slice(3)[0]);
+const myFile = await fs.readFile(path, "utf-8");
+let lines = myFile.split("\n");
+
+if (!isNaN(numLines)) {
+    lines = lines.slice(0, numLines);
+}
+
+lines.forEach((e) => console.log(e));
diff --git a/implement-shell-tools/cat/package.json b/implement-shell-tools/cat/package.json
new file mode 100644
index 000000000..c927a8982
--- /dev/null
+++ b/implement-shell-tools/cat/package.json
@@ -0,0 +1,13 @@
+{
+    "name": "cat",
+    "version": "1.0.0",
+    "description": "You should already be familiar with the `cat` command line tool.",
+    "main": "cat.js",
+    "scripts": {
+        "test": "echo \"Error: no test specified\" && exit 1"
+    },
+    "keywords": [],
+    "author": "",
+    "license": "ISC",
+    "type": "module"
+}

From 8cadca9736a02d7a86a742de9b40e041a128bd4f Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Tue, 21 Jul 2026 21:05:42 +0100
Subject: [PATCH 02/22] a file to test cat functionality

---
 implement-shell-tools/cat/testFile.txt | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 implement-shell-tools/cat/testFile.txt

diff --git a/implement-shell-tools/cat/testFile.txt b/implement-shell-tools/cat/testFile.txt
new file mode 100644
index 000000000..864534491
--- /dev/null
+++ b/implement-shell-tools/cat/testFile.txt
@@ -0,0 +1,4 @@
+This is line 1
+This is line 2
+
+This is line 3 after an empty line
\ No newline at end of file

From 8294ca8db2a8b678e12cc3278b0463aca6612fd8 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 13:22:25 +0100
Subject: [PATCH 03/22] redo: parsing arguments

---
 implement-shell-tools/cat/cat.js | 49 ++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 032e8a475..87fe24cca 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -1,16 +1,47 @@
 import { promises as fs } from "node:fs";
 import process from "node:process";
 
-const path = process.argv.slice(2)[0];
-const numLines = process.argv.slice(3)[0];
+/*
+BASIC requirements:
+single file with no flags:
+    cat sample-files/1.txt
+single file with a valid flag:
+    cat -n sample-files/1.txt
+    cat -b sample-files/1.txt
+read mutliple files with the * wildcard
+    cat -n sample/files/*.txt
 
-// console.log(numLines);
-// console.log(process.argv.slice(3)[0]);
-const myFile = await fs.readFile(path, "utf-8");
-let lines = myFile.split("\n");
+Cat strips trailing new line in file
 
-if (!isNaN(numLines)) {
-    lines = lines.slice(0, numLines);
+-n = number each line
+-b = number each non-empty line
+
+STRETCH GOALS
+-b takes priority when -nb or -bn
+must take in mutiple files:
+  node cat file1.txt file2.txt file3.txt
+  node cat -n file1.txt file2.txt file3.txt
+
+must be able to take in multiple flags or combined flags
+  node cat -bn file.txt
+  node cat -b -n file.txt
+*/
+
+// capturing the user args
+const args = process.argv.slice(2);
+
+let flag;
+const files = [];
+
+// takes only one flag, and accepts whatever the last flag is
+// can parse flag from any position in args
+for (const arg of args) {
+    if (arg === "-n" || arg === "-b") {
+        flag = arg;
+    } else {
+        files.push(arg);
+    }
 }
 
-lines.forEach((e) => console.log(e));
+console.log(`flags: ${flag}`);
+console.log(`files: ${files}`);

From 71441246e657e0227552d8c52a8ec40f218cb4d5 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 13:31:57 +0100
Subject: [PATCH 04/22] Error message if no file supplied.

---
 implement-shell-tools/cat/cat.js | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 87fe24cca..4bcff00eb 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -35,6 +35,8 @@ const files = [];
 
 // takes only one flag, and accepts whatever the last flag is
 // can parse flag from any position in args
+
+// the * (glob expansion is done automatically by the zsh, bash etc. on linux)
 for (const arg of args) {
     if (arg === "-n" || arg === "-b") {
         flag = arg;
@@ -43,5 +45,11 @@ for (const arg of args) {
     }
 }
 
-console.log(`flags: ${flag}`);
-console.log(`files: ${files}`);
+// starting file number, if lines need to be prepended
+let lineNum = 1;
+
+// if no file is supplied
+if (files.length === 0) {
+    console.error("usage: cat [-n] <file...>");
+    process.exit(1); // exit with error
+}

From aeca1f7e5507d3c6ae1466e42b5d7cd59866663c Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 13:33:16 +0100
Subject: [PATCH 05/22] rename file to path

---
 implement-shell-tools/cat/cat.js       | 4 ++--
 implement-shell-tools/cat/testFile.txt | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 4bcff00eb..a2859c783 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -31,7 +31,7 @@ must be able to take in multiple flags or combined flags
 const args = process.argv.slice(2);
 
 let flag;
-const files = [];
+const paths = [];
 
 // takes only one flag, and accepts whatever the last flag is
 // can parse flag from any position in args
@@ -41,7 +41,7 @@ for (const arg of args) {
     if (arg === "-n" || arg === "-b") {
         flag = arg;
     } else {
-        files.push(arg);
+        paths.push(arg);
     }
 }
 
diff --git a/implement-shell-tools/cat/testFile.txt b/implement-shell-tools/cat/testFile.txt
index 864534491..18991b761 100644
--- a/implement-shell-tools/cat/testFile.txt
+++ b/implement-shell-tools/cat/testFile.txt
@@ -1,4 +1,4 @@
 This is line 1
 This is line 2
 
-This is line 3 after an empty line
\ No newline at end of file
+This is line 3 after an empty line

From 1d9d1df854f670c464f20a8cdbe2d8b86111466b Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 14:16:01 +0100
Subject: [PATCH 06/22] finished cat

---
 implement-shell-tools/cat/cat.js       | 78 +++++++++++++++-----------
 implement-shell-tools/cat/testFile.txt |  4 --
 2 files changed, 44 insertions(+), 38 deletions(-)
 delete mode 100644 implement-shell-tools/cat/testFile.txt

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index a2859c783..6a1e74345 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -1,31 +1,8 @@
-import { promises as fs } from "node:fs";
+import { readFileSync } from "node:fs";
 import process from "node:process";
 
-/*
-BASIC requirements:
-single file with no flags:
-    cat sample-files/1.txt
-single file with a valid flag:
-    cat -n sample-files/1.txt
-    cat -b sample-files/1.txt
-read mutliple files with the * wildcard
-    cat -n sample/files/*.txt
-
-Cat strips trailing new line in file
-
--n = number each line
--b = number each non-empty line
-
-STRETCH GOALS
--b takes priority when -nb or -bn
-must take in mutiple files:
-  node cat file1.txt file2.txt file3.txt
-  node cat -n file1.txt file2.txt file3.txt
-
-must be able to take in multiple flags or combined flags
-  node cat -bn file.txt
-  node cat -b -n file.txt
-*/
+// Note: takes only one flag, -n or -b, and accepts whatever the last flag is
+// can parse flag from any position in args
 
 // capturing the user args
 const args = process.argv.slice(2);
@@ -33,10 +10,7 @@ const args = process.argv.slice(2);
 let flag;
 const paths = [];
 
-// takes only one flag, and accepts whatever the last flag is
-// can parse flag from any position in args
-
-// the * (glob expansion is done automatically by the zsh, bash etc. on linux)
+// the * (glob expansion is done automatically by zsh, bash etc. on linux)
 for (const arg of args) {
     if (arg === "-n" || arg === "-b") {
         flag = arg;
@@ -45,11 +19,47 @@ for (const arg of args) {
     }
 }
 
+// if no file is supplied exit with error
+if (paths.length === 0) {
+    console.error("usage: cat [-n] <file...>");
+    process.exit(1);
+}
+
 // starting file number, if lines need to be prepended
 let lineNum = 1;
 
-// if no file is supplied
-if (files.length === 0) {
-    console.error("usage: cat [-n] <file...>");
-    process.exit(1); // exit with error
+for (const path of paths) {
+    let file;
+    try {
+        // using sync as it's a simple short program
+        file = readFileSync(path, "utf-8");
+    } catch (err) {
+        console.error(`cat: ${path}: ${err.message}`);
+        continue; // Real cat continues to next file if current file not found
+    }
+
+    const lines = file.split("\n");
+
+    // remove trailing empty line as this how real cat works
+    if (lines[lines.length - 1] === "") lines.pop();
+
+    if (flag === "-n") {
+        for (const line of lines) {
+            console.log(`${lineNum} ${line}`);
+            lineNum++;
+        }
+    } else if (flag === "-b") {
+        for (const line of lines) {
+            if (line === "") {
+                console.log(line);
+            } else {
+                console.log(`${lineNum} ${line}`);
+                lineNum++;
+            }
+        }
+    } else {
+        for (const line of lines) {
+            console.log(line);
+        }
+    }
 }
diff --git a/implement-shell-tools/cat/testFile.txt b/implement-shell-tools/cat/testFile.txt
deleted file mode 100644
index 18991b761..000000000
--- a/implement-shell-tools/cat/testFile.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-This is line 1
-This is line 2
-
-This is line 3 after an empty line

From d57789975842b0e1078c52243fb085faeef61bbe Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 14:30:05 +0100
Subject: [PATCH 07/22] capture flag arguments

---
 implement-shell-tools/ls/ls.js | 26 ++++++++++++++++++++++++++
 1 file changed, 26 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..03e35a242
--- /dev/null
+++ b/implement-shell-tools/ls/ls.js
@@ -0,0 +1,26 @@
+import fs from "node:fs";
+import process from "node:process";
+
+const args = process.argv.slice(2);
+
+const flags = new Set();
+const path = "";
+
+for (const arg of args) {
+    if (arg.startsWith("-") && arg !== "-") {
+        // capture the flags without the -
+        for (const ch of arg.slice(1)) {
+            flags.add(ch);
+        }
+    }
+}
+
+console.log(flags);
+
+// console.log(
+//     fs.readdir("./", (err, files) => {
+//         if (err) throw err;
+
+//         console.log(files);
+//     }),
+// );

From 4d0e873beba76178fdb2f0610835e6afb4bd2337 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 17:09:43 +0100
Subject: [PATCH 08/22] working subdirectories

---
 implement-shell-tools/ls/ls.js | 43 +++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 03e35a242..c29d76e0c 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -1,26 +1,53 @@
+import { dir } from "node:console";
 import fs from "node:fs";
+import path from "node:path";
 import process from "node:process";
 
 const args = process.argv.slice(2);
 
 const flags = new Set();
-const path = "";
+let paths = [];
+
+if (args.length === 0) {
+    args.push(".");
+}
 
 for (const arg of args) {
     if (arg.startsWith("-") && arg !== "-") {
         // capture the flags without the -
+        // supports combined flags like -1a
         for (const ch of arg.slice(1)) {
             flags.add(ch);
         }
+    } else {
+        paths.push(arg);
     }
 }
 
-console.log(flags);
+const files = [];
+const directories = [];
 
-// console.log(
-//     fs.readdir("./", (err, files) => {
-//         if (err) throw err;
+if (paths.length > 1) {
+    paths.forEach((path) => {
+        if (fs.statSync(path).isDirectory()) {
+            directories.push(path);
+        } else {
+            files.push(path);
+        }
+    });
+} else {
+    fs.readdir(paths[0], (err, files) => console.log(files.join("\t")));
+}
 
-//         console.log(files);
-//     }),
-// );
+if (files.length > 0) {
+    console.log(files.join("\t"));
+}
+
+if (directories.length > 0) {
+    directories.forEach((dir) => {
+        console.log(`\n${dir}:`);
+        fs.readdir(dir, (err, files) => {
+            console.log(files.join("\t"));
+        });
+    });
+}

From 75e9d0a9b224ad9f42905ddc2dada0d3bd608886 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 18:25:19 +0100
Subject: [PATCH 09/22] initial working version

---
 implement-shell-tools/ls/ls.js | 59 ++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 25 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index c29d76e0c..6a7e2da8e 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -1,6 +1,5 @@
 import { dir } from "node:console";
 import fs from "node:fs";
-import path from "node:path";
 import process from "node:process";
 
 const args = process.argv.slice(2);
@@ -8,10 +7,6 @@ const args = process.argv.slice(2);
 const flags = new Set();
 let paths = [];
 
-if (args.length === 0) {
-    args.push(".");
-}
-
 for (const arg of args) {
     if (arg.startsWith("-") && arg !== "-") {
         // capture the flags without the -
@@ -24,30 +19,44 @@ for (const arg of args) {
     }
 }
 
-const files = [];
-const directories = [];
+if (paths.length === 0) {
+    paths.push(".");
+}
 
-if (paths.length > 1) {
-    paths.forEach((path) => {
-        if (fs.statSync(path).isDirectory()) {
-            directories.push(path);
+function printFiles(path) {
+    if (fs.statSync(path).isDirectory()) {
+        if (flags.has("a")) {
+            if (flags.has("1")) {
+                fs.readdirSync(path).forEach((e) => console.log(e));
+            } else {
+                console.log(fs.readdirSync(path).join("\t"));
+            }
         } else {
-            files.push(path);
+            if (flags.has("1")) {
+                fs.readdirSync(path)
+                    .filter((e) => !e.startsWith("."))
+                    .forEach((e) => console.log(e));
+            } else {
+                console.log(
+                    fs
+                        .readdirSync(path)
+                        .filter((e) => !e.startsWith("."))
+                        .join("\t"),
+                );
+            }
         }
-    });
-} else {
-    fs.readdir(paths[0], (err, files) => console.log(files.join("\t")));
-}
-
-if (files.length > 0) {
-    console.log(files.join("\t"));
+    } else {
+        console.log(path);
+    }
 }
 
-if (directories.length > 0) {
-    directories.forEach((dir) => {
-        console.log(`\n${dir}:`);
-        fs.readdir(dir, (err, files) => {
-            console.log(files.join("\t"));
-        });
+if (paths.length === 1) {
+    printFiles(paths[0]);
+} else {
+    paths.forEach((path) => {
+        if (fs.statSync(path).isDirectory()) {
+            console.log(`\n${path}:`);
+        }
+        printFiles(path);
     });
 }

From b77ab503b24511be2d5f28cbb1dd9b6b558ecd98 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 18:45:55 +0100
Subject: [PATCH 10/22] redo: function to get entries for a given path

---
 implement-shell-tools/ls/ls.js | 44 ++++++++--------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 6a7e2da8e..526334bd8 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -1,5 +1,6 @@
 import { dir } from "node:console";
 import fs from "node:fs";
+import path from "node:path";
 import process from "node:process";
 
 const args = process.argv.slice(2);
@@ -23,40 +24,15 @@ if (paths.length === 0) {
     paths.push(".");
 }
 
-function printFiles(path) {
-    if (fs.statSync(path).isDirectory()) {
-        if (flags.has("a")) {
-            if (flags.has("1")) {
-                fs.readdirSync(path).forEach((e) => console.log(e));
-            } else {
-                console.log(fs.readdirSync(path).join("\t"));
-            }
-        } else {
-            if (flags.has("1")) {
-                fs.readdirSync(path)
-                    .filter((e) => !e.startsWith("."))
-                    .forEach((e) => console.log(e));
-            } else {
-                console.log(
-                    fs
-                        .readdirSync(path)
-                        .filter((e) => !e.startsWith("."))
-                        .join("\t"),
-                );
-            }
-        }
-    } else {
-        console.log(path);
+// returns all entries for a given path
+// if -a flag, then include dotfiles, else exclude dotfiles
+function getPathEntries(path, aFlag = flags.has("a")) {
+    let entries = fs.readdirSync(path);
+
+    if (!aFlag) {
+        entries = entries.filter((e) => !e.startsWith("."));
     }
+    return entries;
 }
 
-if (paths.length === 1) {
-    printFiles(paths[0]);
-} else {
-    paths.forEach((path) => {
-        if (fs.statSync(path).isDirectory()) {
-            console.log(`\n${path}:`);
-        }
-        printFiles(path);
-    });
-}
+console.log(getPathEntries(paths[0]));

From abce30aacdcc540cf3c6200223256c9fc5cc485b Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 18:54:14 +0100
Subject: [PATCH 11/22] printing entries for a single path

---
 implement-shell-tools/ls/ls.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 526334bd8..9441b9844 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -35,4 +35,14 @@ function getPathEntries(path, aFlag = flags.has("a")) {
     return entries;
 }
 
-console.log(getPathEntries(paths[0]));
+// formatter: if -1 flag, print entry per line
+// else all in one line with
+function printEntries(entries, onePerLineFlag = flags.has("1")) {
+    if (onePerLineFlag) {
+        entries.forEach((e) => console.log(e));
+    } else {
+        console.log(entries.join("\t"));
+    }
+}
+
+printEntries(getPathEntries(paths[0]));

From 98c1c435f4ded760ba1951ccb733d655b58323a9 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Thu, 23 Jul 2026 19:33:39 +0100
Subject: [PATCH 12/22] ls done

---
 implement-shell-tools/ls/ls.js | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 9441b9844..7fc3286c1 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -1,6 +1,4 @@
-import { dir } from "node:console";
 import fs from "node:fs";
-import path from "node:path";
 import process from "node:process";
 
 const args = process.argv.slice(2);
@@ -41,8 +39,28 @@ function printEntries(entries, onePerLineFlag = flags.has("1")) {
     if (onePerLineFlag) {
         entries.forEach((e) => console.log(e));
     } else {
-        console.log(entries.join("\t"));
+        // if join on empty entries arr, add extra blank line
+        if (entries.length !== 0) {
+            console.log(entries.join("\t"));
+        }
     }
 }
 
-printEntries(getPathEntries(paths[0]));
+// this is needed to group files at the top and folers at the bottom when giving mutiple path arguements
+// to argv e.g. node ls.js sample-files/*
+const fileArgs = paths.filter((p) => !fs.statSync(p).isDirectory());
+const dirArgs = paths.filter((p) => fs.statSync(p).isDirectory());
+
+// First print all plain file arguments together, as one group
+if (fileArgs.length > 0) {
+    printEntries(fileArgs);
+}
+
+// Then print each directory's listing, with headers if needed
+dirArgs.forEach((path, index) => {
+    if (paths.length > 1) {
+        if (index > 0 || fileArgs.length > 0) console.log("");
+        console.log(`${path}:`);
+    }
+    printEntries(getPathEntries(path));
+});

From 5e36e1fccc18b08a5495f9ede132c9ed0b0cfa4b Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Sat, 25 Jul 2026 15:06:40 +0100
Subject: [PATCH 13/22] fix: cat line numbering is per file, not on the
 concatanation of files

---
 implement-shell-tools/cat/cat.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 6a1e74345..ff592b5f0 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -26,9 +26,9 @@ if (paths.length === 0) {
 }
 
 // starting file number, if lines need to be prepended
-let lineNum = 1;
 
 for (const path of paths) {
+    let lineNum = 1;
     let file;
     try {
         // using sync as it's a simple short program

From 1a27139ec3825d17d0423ad30be9defb5b97308e Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Sat, 25 Jul 2026 17:14:25 +0100
Subject: [PATCH 14/22] mode switching arg parser

---
 implement-shell-tools/ls/ls.js | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 7fc3286c1..2113bcc99 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -6,18 +6,23 @@ const args = process.argv.slice(2);
 const flags = new Set();
 let paths = [];
 
-for (const arg of args) {
-    if (arg.startsWith("-") && arg !== "-") {
+let isFlag = true;
+for (let i = 0; i < args.length; i++) {
+    if (isFlag && args[i] === "--") {
+        isFlag = false;
+    } else if (isFlag && args[i].startsWith("-") && args[i] !== "-") {
         // capture the flags without the -
         // supports combined flags like -1a
-        for (const ch of arg.slice(1)) {
+        for (const ch of args[i].slice(1)) {
             flags.add(ch);
         }
     } else {
-        paths.push(arg);
+        paths.push(args[i]);
     }
 }
 
+console.log(paths);
+
 if (paths.length === 0) {
     paths.push(".");
 }

From 667e3bbf6c753104f27502ce2aa346f78b9f9932 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 08:21:57 +0100
Subject: [PATCH 15/22] clean up

---
 implement-shell-tools/ls/ls.js | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/implement-shell-tools/ls/ls.js b/implement-shell-tools/ls/ls.js
index 2113bcc99..ddbc14e13 100644
--- a/implement-shell-tools/ls/ls.js
+++ b/implement-shell-tools/ls/ls.js
@@ -7,22 +7,20 @@ const flags = new Set();
 let paths = [];
 
 let isFlag = true;
-for (let i = 0; i < args.length; i++) {
-    if (isFlag && args[i] === "--") {
+for (const arg of args) {
+    if (isFlag && arg === "--") {
         isFlag = false;
-    } else if (isFlag && args[i].startsWith("-") && args[i] !== "-") {
+    } else if (isFlag && arg.startsWith("-") && arg !== "-") {
         // capture the flags without the -
         // supports combined flags like -1a
-        for (const ch of args[i].slice(1)) {
+        for (const ch of arg.slice(1)) {
             flags.add(ch);
         }
     } else {
-        paths.push(args[i]);
+        paths.push(arg);
     }
 }
 
-console.log(paths);
-
 if (paths.length === 0) {
     paths.push(".");
 }

From c7449be1d9ce405333e1a8318af339ba1f983c2a Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 09:21:45 +0100
Subject: [PATCH 16/22] Parse optoins using commander

---
 implement-shell-tools/wc/package-lock.json | 25 ++++++++++++++++++++++
 implement-shell-tools/wc/package.json      | 16 ++++++++++++++
 implement-shell-tools/wc/wc.js             | 14 ++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 implement-shell-tools/wc/package-lock.json
 create mode 100644 implement-shell-tools/wc/package.json
 create mode 100644 implement-shell-tools/wc/wc.js

diff --git a/implement-shell-tools/wc/package-lock.json b/implement-shell-tools/wc/package-lock.json
new file mode 100644
index 000000000..11fb6ab6f
--- /dev/null
+++ b/implement-shell-tools/wc/package-lock.json
@@ -0,0 +1,25 @@
+{
+    "name": "wc",
+    "version": "1.0.0",
+    "lockfileVersion": 3,
+    "requires": true,
+    "packages": {
+        "": {
+            "name": "wc",
+            "version": "1.0.0",
+            "license": "ISC",
+            "dependencies": {
+                "commander": "^15.0.0"
+            }
+        },
+        "node_modules/commander": {
+            "version": "15.0.0",
+            "resolved": "https://registry.npmjs.org/commander/-/commander-15.0.0.tgz",
+            "integrity": "sha512-z67u4ZhzCL/Tydu1lJARtEZYWbWaN7oYLHbsuzocr6y4N6WZAagG3RQ4FW61V1/0+jImpj293XfrcYnd1qxtPg==",
+            "license": "MIT",
+            "engines": {
+                "node": ">=22.12.0"
+            }
+        }
+    }
+}
diff --git a/implement-shell-tools/wc/package.json b/implement-shell-tools/wc/package.json
new file mode 100644
index 000000000..489705b8d
--- /dev/null
+++ b/implement-shell-tools/wc/package.json
@@ -0,0 +1,16 @@
+{
+    "name": "wc",
+    "version": "1.0.0",
+    "description": "You should already be familiar with the `wc` command line tool.",
+    "main": "wc.js",
+    "scripts": {
+        "test": "echo \"Error: no test specified\" && exit 1"
+    },
+    "keywords": [],
+    "author": "",
+    "license": "ISC",
+    "type": "module",
+    "dependencies": {
+        "commander": "^15.0.0"
+    }
+}
diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
new file mode 100644
index 000000000..9919c1d26
--- /dev/null
+++ b/implement-shell-tools/wc/wc.js
@@ -0,0 +1,14 @@
+import { program } from "commander";
+
+program
+    .name("wc")
+    .description("Mimics the wc command line tool")
+    .option("-w")
+    .option("-c")
+    .option("-l");
+
+program.parse();
+
+const options = program.opts();
+
+console.log(options);

From 45766e070bf45ecc94d75f7cb7d820e95b13efe3 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 09:35:32 +0100
Subject: [PATCH 17/22] parse file arguments

---
 implement-shell-tools/wc/wc.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 9919c1d26..e71d39c80 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -1,14 +1,18 @@
 import { program } from "commander";
+import fs from "node:fs";
+import process from "node:process";
 
 program
     .name("wc")
     .description("Mimics the wc command line tool")
     .option("-w")
     .option("-c")
-    .option("-l");
+    .option("-l")
+    .argument("<files...>", "file to process");
 
 program.parse();
 
 const options = program.opts();
+const files = program.args;
 
-console.log(options);
+console.log(files);

From 2c3458fcbae16c0d9fa4c33733c94aee0d27e3e8 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 09:58:23 +0100
Subject: [PATCH 18/22] handle no flag arguments

---
 implement-shell-tools/wc/wc.js | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index e71d39c80..fa545de5e 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -15,4 +15,19 @@ program.parse();
 const options = program.opts();
 const files = program.args;
 
+console.log(options);
 console.log(files);
+
+// if no -lwc flags are supplied, wc prints
+// lines, words, bytes of each file
+// whereas if any flags are supplied only those
+// values are printed
+if (Object.keys(options).length === 0) {
+    options.l = options.w = options.c = true;
+}
+
+/*
+array of objects with data [{l: 2, w: 12: c: 123, file: 'sample-files/1.txt}, ...]
+For each item, create a temp string
+If options.l, append to temp string the w value
+*/

From 3c8e345452bd7a2374c830c724bef40267d5a7a4 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 10:26:29 +0100
Subject: [PATCH 19/22] shows error message if trying to read a dictory

---
 implement-shell-tools/wc/wc.js | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index fa545de5e..16c97ef88 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -1,5 +1,5 @@
 import { program } from "commander";
-import fs from "node:fs";
+import fs, { chownSync } from "node:fs";
 import process from "node:process";
 
 program
@@ -13,10 +13,10 @@ program
 program.parse();
 
 const options = program.opts();
-const files = program.args;
+const paths = program.args;
 
 console.log(options);
-console.log(files);
+console.log(paths);
 
 // if no -lwc flags are supplied, wc prints
 // lines, words, bytes of each file
@@ -27,7 +27,24 @@ if (Object.keys(options).length === 0) {
 }
 
 /*
-array of objects with data [{l: 2, w: 12: c: 123, file: 'sample-files/1.txt}, ...]
-For each item, create a temp string
-If options.l, append to temp string the w value
+for each path:
+    if path is not a directory, show error message
+    else:
+        create a temporary array
+        if l in options:
+            push line count to temp arr
+        if w in options:
+            push word count into temp arr
+        if c in options:
+           push byte count into data 
+    
+    join the array with path and print
 */
+
+for (const path of paths) {
+    if (fs.statSync(path).isDirectory()) {
+        console.log(`wc: ${path}: read: Is a directory`);
+    } else {
+        console.log(`${path} is a file`);
+    }
+}

From 1a80d5b5458f75f15a63b1651e3a05a3adbb4725 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 11:24:00 +0100
Subject: [PATCH 20/22] prints lwc for one or more files

---
 implement-shell-tools/wc/wc.js | 53 ++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 19 deletions(-)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 16c97ef88..83c33d995 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -8,16 +8,13 @@ program
     .option("-w")
     .option("-c")
     .option("-l")
-    .argument("<files...>", "file to process");
+    .argument("<files...>", "files to process");
 
 program.parse();
 
 const options = program.opts();
 const paths = program.args;
 
-console.log(options);
-console.log(paths);
-
 // if no -lwc flags are supplied, wc prints
 // lines, words, bytes of each file
 // whereas if any flags are supplied only those
@@ -26,25 +23,43 @@ if (Object.keys(options).length === 0) {
     options.l = options.w = options.c = true;
 }
 
-/*
-for each path:
-    if path is not a directory, show error message
-    else:
-        create a temporary array
-        if l in options:
-            push line count to temp arr
-        if w in options:
-            push word count into temp arr
-        if c in options:
-           push byte count into data 
-    
-    join the array with path and print
-*/
+// keeps track of total values for each of the data
+// incrementally updated in the loop below
+const totals = { l: 0, w: 0, c: 0 };
 
 for (const path of paths) {
     if (fs.statSync(path).isDirectory()) {
         console.log(`wc: ${path}: read: Is a directory`);
     } else {
-        console.log(`${path} is a file`);
+        let outputStr = "";
+        const file = fs.readFileSync(path, "utf-8");
+        if (options.l) {
+            const lines = file.split("\n");
+            // exclude trailing empty line from count
+            if (lines.at(-1) === "") {
+                lines.pop();
+            }
+            const lineCount = lines.length;
+            totals.l += lineCount;
+            outputStr += `\t${lineCount}`;
+        }
+
+        if (options.w) {
+            // real wc splits not just on " ", but on white spaces more generally
+            const words = file.split(/\s+/).filter(Boolean);
+            const wordCount = words.length;
+            totals.w += wordCount;
+            outputStr += `\t${wordCount}`;
+        }
+
+        if (options.c) {
+            file.size;
+            const byteCount = fs.statSync(path).size;
+            totals.c += byteCount;
+            outputStr += `\t${byteCount}`;
+        }
+
+        outputStr += ` ${path}`;
+        console.log(outputStr);
     }
 }

From bdfbbbabcc4dee82e5efcd9afea5994b98c57506 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 11:29:34 +0100
Subject: [PATCH 21/22] print totals in bottom row if more than one file

---
 implement-shell-tools/wc/wc.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 83c33d995..14bb763ee 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -27,10 +27,12 @@ if (Object.keys(options).length === 0) {
 // incrementally updated in the loop below
 const totals = { l: 0, w: 0, c: 0 };
 
+let fileCount = 0;
 for (const path of paths) {
     if (fs.statSync(path).isDirectory()) {
         console.log(`wc: ${path}: read: Is a directory`);
     } else {
+        fileCount++;
         let outputStr = "";
         const file = fs.readFileSync(path, "utf-8");
         if (options.l) {
@@ -63,3 +65,7 @@ for (const path of paths) {
         console.log(outputStr);
     }
 }
+
+if (fileCount > 1) {
+    console.log(`\t${totals.l}\t${totals.w}\t${totals.c} total`);
+}

From 0b3d37dcd5d8f9124a05824b33df38ce1d6e9550 Mon Sep 17 00:00:00 2001
From: Raihan Sharif <raihansharif92@gmail.com>
Date: Mon, 27 Jul 2026 11:34:49 +0100
Subject: [PATCH 22/22] correctly print out totals, includning flags

---
 implement-shell-tools/wc/wc.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/implement-shell-tools/wc/wc.js b/implement-shell-tools/wc/wc.js
index 14bb763ee..3cb4c8cbc 100644
--- a/implement-shell-tools/wc/wc.js
+++ b/implement-shell-tools/wc/wc.js
@@ -66,6 +66,10 @@ for (const path of paths) {
     }
 }
 
+// if there's more than one file, print out a total
+// if a flag is not selected, then the value for that flag is 0
+// filter out anything with a total of 0
 if (fileCount > 1) {
-    console.log(`\t${totals.l}\t${totals.w}\t${totals.c} total`);
+    const totalsArr = Object.values(totals).filter((elem) => elem !== 0);
+    console.log(`\t${totalsArr.join("\t")} total`);
 }