From 592fb58e4a7699b7817d86b43ce404c71abb9d68 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 15:13:56 +0100
Subject: [PATCH 1/8] =?UTF-8?q?ls:=20complete=20scripts=2001=E2=80=9304?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 individual-shell-tools/ls/script-01.sh | 1 +
 individual-shell-tools/ls/script-02.sh | 1 +
 individual-shell-tools/ls/script-03.sh | 1 +
 individual-shell-tools/ls/script-04.sh | 2 ++
 4 files changed, 5 insertions(+)

diff --git a/individual-shell-tools/ls/script-01.sh b/individual-shell-tools/ls/script-01.sh
index 241b62f5e..72f2fb4a6 100755
--- a/individual-shell-tools/ls/script-01.sh
+++ b/individual-shell-tools/ls/script-01.sh
@@ -13,3 +13,4 @@ fi
 
 # TODO: Write a command to list the files and folders in this directory.
 # The output should be a list of names including child-directory, script-01.sh, script-02.sh, and more.
+ls 
diff --git a/individual-shell-tools/ls/script-02.sh b/individual-shell-tools/ls/script-02.sh
index d0a5a10f4..d37175729 100755
--- a/individual-shell-tools/ls/script-02.sh
+++ b/individual-shell-tools/ls/script-02.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command which lists all of the files in the directory named child-directory.
 # The output should be a list of names: helper-1.txt, helper-2.txt, helper-3.txt.
+ls child-directory
diff --git a/individual-shell-tools/ls/script-03.sh b/individual-shell-tools/ls/script-03.sh
index 781216d21..8f0627b5f 100755
--- a/individual-shell-tools/ls/script-03.sh
+++ b/individual-shell-tools/ls/script-03.sh
@@ -5,3 +5,4 @@ set -euo pipefail
 # TODO: Write a command which _recursively_ lists all of the files and folders in this directory _and_ all of the files inside those folders.
 # The output should be a list of names including: child-directory, script-01.sh, helper-1.txt (and more).
 # The formatting of the output doesn't matter.
+ls -R 
diff --git a/individual-shell-tools/ls/script-04.sh b/individual-shell-tools/ls/script-04.sh
index 72f3817b3..ae225dc8a 100755
--- a/individual-shell-tools/ls/script-04.sh
+++ b/individual-shell-tools/ls/script-04.sh
@@ -16,8 +16,10 @@ echo "First exercise (sorted newest to oldest):"
 # TODO: Write a command which lists the files in the child-directory directory, one per line, sorted so that the most recently modified file is first.
 # The output should be a list of names in this order, one per line: helper-3.txt, helper-1.txt, helper-2.txt.
 
+ls -t1 ./child-directory
 
 echo "Second exercise (sorted oldest to newest):"
 
 # TODO: Write a command which does the same as above, but sorted in the opposite order (oldest first).
 # The output should be a list of names in this order, one per line: helper-2.txt, helper-1.txt, helper-3.txt.
+ls -tr1 child-directory

From 67fefff76bdf7c3a33ef9322ee20f652a5073b73 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 17:33:27 +0100
Subject: [PATCH 2/8] =?UTF-8?q?cat:=20complete=20scripts=2001=E2=80=9304?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 individual-shell-tools/cat/script-01.sh         | 1 +
 individual-shell-tools/cat/script-02.sh         | 1 +
 individual-shell-tools/cat/script-03.sh         | 1 +
 individual-shell-tools/cat/script-04-stretch.sh | 2 ++
 4 files changed, 5 insertions(+)

diff --git a/individual-shell-tools/cat/script-01.sh b/individual-shell-tools/cat/script-01.sh
index c85053e0f..edcc54fb4 100755
--- a/individual-shell-tools/cat/script-01.sh
+++ b/individual-shell-tools/cat/script-01.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the contents of the helper-1.txt file inside the helper-files directory to the terminal.
 # The output of this command should be "Once upon a time...".
+cat ../helper-files/helper-1.txt
diff --git a/individual-shell-tools/cat/script-02.sh b/individual-shell-tools/cat/script-02.sh
index 01bbd5eab..d8187ff42 100755
--- a/individual-shell-tools/cat/script-02.sh
+++ b/individual-shell-tools/cat/script-02.sh
@@ -11,3 +11,4 @@ set -euo pipefail
 # It looked delicious.
 # I was tempted to take a bite of it.
 # But this seemed like a bad idea...
+cat ../helper-files/*
diff --git a/individual-shell-tools/cat/script-03.sh b/individual-shell-tools/cat/script-03.sh
index 37573b0c1..dd6b1d8b1 100755
--- a/individual-shell-tools/cat/script-03.sh
+++ b/individual-shell-tools/cat/script-03.sh
@@ -9,3 +9,4 @@ set -euo pipefail
 # 1 It looked delicious.
 # 2 I was tempted to take a bite of it.
 # 3 But this seemed like a bad idea...
+cat -n ../helper-files/helper-3.txt
diff --git a/individual-shell-tools/cat/script-04-stretch.sh b/individual-shell-tools/cat/script-04-stretch.sh
index 00fe3c48b..7cff10579 100755
--- a/individual-shell-tools/cat/script-04-stretch.sh
+++ b/individual-shell-tools/cat/script-04-stretch.sh
@@ -13,3 +13,5 @@ set -euo pipefail
 # 3 It looked delicious.
 # 4 I was tempted to take a bite of it.
 # 5 But this seemed like a bad idea...
+
+cat  ../helper-files/* | nl

From 6a88ca891cdc3083f7cb0e9728eaaddb01ef5c10 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 18:22:17 +0100
Subject: [PATCH 3/8] wc: complete script 03

---
 individual-shell-tools/wc/script-01.sh | 1 +
 individual-shell-tools/wc/script-02.sh | 2 ++
 individual-shell-tools/wc/script-03.sh | 1 +
 3 files changed, 4 insertions(+)

diff --git a/individual-shell-tools/wc/script-01.sh b/individual-shell-tools/wc/script-01.sh
index c9dd6e5df..5374c0db0 100755
--- a/individual-shell-tools/wc/script-01.sh
+++ b/individual-shell-tools/wc/script-01.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the number of words in the file helper-files/helper-3.txt.
 # The output should include the number 19. The output should not include the number 92.
+wc -w < helper-files/helper-3.txt
diff --git a/individual-shell-tools/wc/script-02.sh b/individual-shell-tools/wc/script-02.sh
index 8feeb1a62..23f7aace0 100755
--- a/individual-shell-tools/wc/script-02.sh
+++ b/individual-shell-tools/wc/script-02.sh
@@ -4,3 +4,5 @@ set -euo pipefail
 
 # TODO: Write a command to output the number of lines in the file helper-files/helper-3.txt.
 # The output should include the number 3. The output should not include the number 19.
+
+wc -l < helper-files/helper-3.txt
diff --git a/individual-shell-tools/wc/script-03.sh b/individual-shell-tools/wc/script-03.sh
index 6b2e9d3d1..d49dd69e4 100755
--- a/individual-shell-tools/wc/script-03.sh
+++ b/individual-shell-tools/wc/script-03.sh
@@ -8,3 +8,4 @@ set -euo pipefail
 #        1       7      39 ../helper-files/helper-2.txt
 #        3      19      92 ../helper-files/helper-3.txt
 #        5      30     151 total
+wc ./helper-files/*

From 921cf7695ea357f51141628ec324b6188a9976ed Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 19:24:50 +0100
Subject: [PATCH 4/8] grep: complete scripts 01-07

---
 individual-shell-tools/grep/script-01.sh | 3 +++
 individual-shell-tools/grep/script-02.sh | 2 ++
 individual-shell-tools/grep/script-03.sh | 1 +
 individual-shell-tools/grep/script-04.sh | 2 ++
 individual-shell-tools/grep/script-05.sh | 1 +
 individual-shell-tools/grep/script-06.sh | 1 +
 individual-shell-tools/grep/script-07.sh | 1 +
 7 files changed, 11 insertions(+)

diff --git a/individual-shell-tools/grep/script-01.sh b/individual-shell-tools/grep/script-01.sh
index fb05f42f2..712c290af 100755
--- a/individual-shell-tools/grep/script-01.sh
+++ b/individual-shell-tools/grep/script-01.sh
@@ -4,3 +4,6 @@ set -euo pipefail
 
 # TODO: Write a command to output every line in dialogue.txt said by the Doctor.
 # The output should contain 6 lines.
+#!/bin/bash
+
+grep "^Doctor:" dialogue.txt
diff --git a/individual-shell-tools/grep/script-02.sh b/individual-shell-tools/grep/script-02.sh
index df6f85640..2fdd98944 100755
--- a/individual-shell-tools/grep/script-02.sh
+++ b/individual-shell-tools/grep/script-02.sh
@@ -4,3 +4,5 @@ set -euo pipefail
 
 # TODO: Write a command to output every line in dialogue.txt that contains the word Doctor (regardless of case).
 # The output should contain 9 lines.
+
+grep -i "Doctor" dialogue.txt
diff --git a/individual-shell-tools/grep/script-03.sh b/individual-shell-tools/grep/script-03.sh
index 5383fe578..37b2174fe 100755
--- a/individual-shell-tools/grep/script-03.sh
+++ b/individual-shell-tools/grep/script-03.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the number of lines in dialogue.txt that contain the word Doctor (regardless of case).
 # The output should be exactly the number 9.
+grep -i -c "Doctor" dialogue.txt
diff --git a/individual-shell-tools/grep/script-04.sh b/individual-shell-tools/grep/script-04.sh
index 80ee04776..6a1cc719c 100755
--- a/individual-shell-tools/grep/script-04.sh
+++ b/individual-shell-tools/grep/script-04.sh
@@ -4,3 +4,5 @@ set -euo pipefail
 
 # TODO: Write a command to output every line in dialogue.txt that does not contain the word "Hello" (regardless of case).
 # The output should contain 10 lines.
+
+grep -vi "Hello" dialogue.txt
diff --git a/individual-shell-tools/grep/script-05.sh b/individual-shell-tools/grep/script-05.sh
index 1eb538185..d4115cec7 100755
--- a/individual-shell-tools/grep/script-05.sh
+++ b/individual-shell-tools/grep/script-05.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output every line in dialogue.txt that contains the string "cure", as well as the line before that line.
 # The output should contain two pairs of two lines of text (with a separator between them).
+grep -B 1 "cure" dialogue.txt
diff --git a/individual-shell-tools/grep/script-06.sh b/individual-shell-tools/grep/script-06.sh
index 5670e3b6c..0e8244ff7 100755
--- a/individual-shell-tools/grep/script-06.sh
+++ b/individual-shell-tools/grep/script-06.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the name of every `.txt` file in this directory which contains a line of dialogue said by the Doctor.
 # The output should contain two filenames.
+grep -l "^Doctor:" *.txt
diff --git a/individual-shell-tools/grep/script-07.sh b/individual-shell-tools/grep/script-07.sh
index 9670ebad9..9fabc87f0 100755
--- a/individual-shell-tools/grep/script-07.sh
+++ b/individual-shell-tools/grep/script-07.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output, for each `.txt` file in this directory, how many lines of dialogue the Doctor has.
 # The output should show that dialogue.txt contains 6 lines, dialogue-2.txt contains 2, and dialogue-3.txt contains 0.
+grep -c "^Doctor:" *.txt

From 9155d05b4d4e16cc7066b319585e1320743878d5 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 19:40:39 +0100
Subject: [PATCH 5/8] sed: complete script 01-06

---
 individual-shell-tools/sed/script-01.sh | 1 +
 individual-shell-tools/sed/script-02.sh | 1 +
 individual-shell-tools/sed/script-03.sh | 2 ++
 individual-shell-tools/sed/script-04.sh | 1 +
 individual-shell-tools/sed/script-05.sh | 1 +
 individual-shell-tools/sed/script-06.sh | 1 +
 6 files changed, 7 insertions(+)

diff --git a/individual-shell-tools/sed/script-01.sh b/individual-shell-tools/sed/script-01.sh
index 3eba6fa4d..48ea0a0ec 100755
--- a/individual-shell-tools/sed/script-01.sh
+++ b/individual-shell-tools/sed/script-01.sh
@@ -5,3 +5,4 @@ set -euo pipefail
 # TODO: Write a command to output input.txt with all occurrences of the letter `i` replaced with `I`.
 # The output should contain 11 lines.
 # The first line of the output should be: "ThIs Is a sample fIle for experImentIng with sed.".
+sed 's/i/I/g' input.txt
diff --git a/individual-shell-tools/sed/script-02.sh b/individual-shell-tools/sed/script-02.sh
index abdd64d06..be485a0af 100755
--- a/individual-shell-tools/sed/script-02.sh
+++ b/individual-shell-tools/sed/script-02.sh
@@ -5,3 +5,4 @@ set -euo pipefail
 # TODO: Write a command to output input.txt with numbers removed.
 # The output should contain 11 lines.
 # Line 6 of the output should be " Alisha".
+sed 's/[0-9]//g' input.txt
diff --git a/individual-shell-tools/sed/script-03.sh b/individual-shell-tools/sed/script-03.sh
index dd284a296..e70f4a600 100755
--- a/individual-shell-tools/sed/script-03.sh
+++ b/individual-shell-tools/sed/script-03.sh
@@ -4,3 +4,5 @@ set -euo pipefail
 
 # TODO: Write a command to output input.txt removing any line which contains a number.
 # The output should contain 6 lines.
+
+sed '/[0-9]/d' input.txt
diff --git a/individual-shell-tools/sed/script-04.sh b/individual-shell-tools/sed/script-04.sh
index 0052ac6c4..781898523 100755
--- a/individual-shell-tools/sed/script-04.sh
+++ b/individual-shell-tools/sed/script-04.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output input.txt replacing every occurrence of the string "We'll" with "We will".
 # The output should contain 11 lines.
+sed "s/We'll/We will/g" input.txt
diff --git a/individual-shell-tools/sed/script-05.sh b/individual-shell-tools/sed/script-05.sh
index 2dcc91a0c..0d772b14f 100755
--- a/individual-shell-tools/sed/script-05.sh
+++ b/individual-shell-tools/sed/script-05.sh
@@ -6,3 +6,4 @@ set -euo pipefail
 # If a line starts with a number and a space, make the line instead end with a space and the number.
 # So line 6 which currently reads "37 Alisha" should instead read "Alisha 37".
 # The output should contain 11 lines.
+sed -E 's/^([0-9]+) (.*)$/\2 \1/' input.txt
diff --git a/individual-shell-tools/sed/script-06.sh b/individual-shell-tools/sed/script-06.sh
index 0b9390170..9331f9074 100755
--- a/individual-shell-tools/sed/script-06.sh
+++ b/individual-shell-tools/sed/script-06.sh
@@ -8,3 +8,4 @@ set -euo pipefail
 # The output should contain 11 lines.
 # Line 3 should be "It contains many lines, and there are some things you may want to do with each of them.".
 # Line 11 should be "We also should remember, when we go shopping, to get 4 items: oranges, cheese, bread, olives.".
+sed 's/,\([^ ]\)/, \1/g' input.txt

From 6c80f3823b88fca666f1ad4665b121347f81cd96 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Thu, 18 Sep 2025 19:53:33 +0100
Subject: [PATCH 6/8] awk: complete script 01-07

---
 individual-shell-tools/awk/1                    | 7 +++++++
 individual-shell-tools/awk/3                    | 7 +++++++
 individual-shell-tools/awk/script-01.sh         | 1 +
 individual-shell-tools/awk/script-02.sh         | 1 +
 individual-shell-tools/awk/script-03.sh         | 2 ++
 individual-shell-tools/awk/script-04.sh         | 1 +
 individual-shell-tools/awk/script-05.sh         | 1 +
 individual-shell-tools/awk/script-06-stretch.sh | 1 +
 individual-shell-tools/awk/script-07-stretch.sh | 5 +++++
 9 files changed, 26 insertions(+)
 create mode 100644 individual-shell-tools/awk/1
 create mode 100644 individual-shell-tools/awk/3

diff --git a/individual-shell-tools/awk/1 b/individual-shell-tools/awk/1
new file mode 100644
index 000000000..7ab2a6dc9
--- /dev/null
+++ b/individual-shell-tools/awk/1
@@ -0,0 +1,7 @@
+5
+5
+6
+5
+5
+7
+0
diff --git a/individual-shell-tools/awk/3 b/individual-shell-tools/awk/3
new file mode 100644
index 000000000..7ab2a6dc9
--- /dev/null
+++ b/individual-shell-tools/awk/3
@@ -0,0 +1,7 @@
+5
+5
+6
+5
+5
+7
+0
diff --git a/individual-shell-tools/awk/script-01.sh b/individual-shell-tools/awk/script-01.sh
index 8db4390af..a8030379e 100755
--- a/individual-shell-tools/awk/script-01.sh
+++ b/individual-shell-tools/awk/script-01.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output just the names of each player in `scores-table.txt`.
 # Your output should contain 6 lines, each with just one word on it.
+awk '{ print $1 }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-02.sh b/individual-shell-tools/awk/script-02.sh
index 5956be9bd..a40c4bc8c 100755
--- a/individual-shell-tools/awk/script-02.sh
+++ b/individual-shell-tools/awk/script-02.sh
@@ -4,3 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the names of each player, as well as their city.
 # Your output should contain 6 lines, each with two words on it, separated by a space.
+awk '{ print $1, $2 }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-03.sh b/individual-shell-tools/awk/script-03.sh
index af7c6e8b9..7934245e9 100755
--- a/individual-shell-tools/awk/script-03.sh
+++ b/individual-shell-tools/awk/script-03.sh
@@ -5,3 +5,5 @@ set -euo pipefail
 # TODO: Write a command to output just the names of each player along with the score from their first attempt.
 # Your output should contain 6 lines, each with one word and one number on it.
 # The first line should be "Ahmed 1".
+
+awk '{ print $1, $3 }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-04.sh b/individual-shell-tools/awk/script-04.sh
index bf15703c7..1aecc5dd8 100755
--- a/individual-shell-tools/awk/script-04.sh
+++ b/individual-shell-tools/awk/script-04.sh
@@ -5,3 +5,4 @@ set -euo pipefail
 # TODO: Write a command to output just the names of each player in London along with the score from their last attempt.
 # Your output should contain 3 lines, each with one word and one number on it.
 # The first line should be "Ahmed 4".
+awk '$2 == "London" { print $1, $NF }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-05.sh b/individual-shell-tools/awk/script-05.sh
index d1680cb02..2cd88a62d 100755
--- a/individual-shell-tools/awk/script-05.sh
+++ b/individual-shell-tools/awk/script-05.sh
@@ -5,3 +5,4 @@ set -euo pipefail
 # TODO: Write a command to output just the names of each player along with the number of times they've played the game.
 # Your output should contain 6 lines, each with one word and one number on it.
 # The first line should be "Ahmed 3".
+awk '{ print $1, NF - 2 }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-06-stretch.sh b/individual-shell-tools/awk/script-06-stretch.sh
index 0201e6378..f79ad384f 100755
--- a/individual-shell-tools/awk/script-06-stretch.sh
+++ b/individual-shell-tools/awk/script-06-stretch.sh
@@ -6,3 +6,4 @@ set -euo pipefail
 
 # TODO: Write a command to output the total of adding together all players' first scores.
 # Your output should be exactly the number 54.
+awk '{ sum += $3 } END { print sum }' scores-table.txt
diff --git a/individual-shell-tools/awk/script-07-stretch.sh b/individual-shell-tools/awk/script-07-stretch.sh
index 3f7155880..9b6a716b8 100755
--- a/individual-shell-tools/awk/script-07-stretch.sh
+++ b/individual-shell-tools/awk/script-07-stretch.sh
@@ -7,3 +7,8 @@ set -euo pipefail
 # TODO: Write a command to output just the names of each player along with the total of adding all of that player's scores.
 # Your output should contain 6 lines, each with one word and one number on it.
 # The first line should be "Ahmed 15". The second line should be "Basia 37"
+awk '{
+  sum = 0
+  for (i = 3; i <= NF; i++) sum += $i
+  print $1, sum
+}' scores-table.txt

From 054fcc7fe05e529a2bf37a325946a090cca48655 Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Sat, 20 Sep 2025 22:49:11 +0100
Subject: [PATCH 7/8] cat initial implementation- no flags yet

---
 implement-shell-tools/cat/.gitignore |  2 ++
 implement-shell-tools/cat/cat.js     | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 implement-shell-tools/cat/.gitignore
 create mode 100644 implement-shell-tools/cat/cat.js

diff --git a/implement-shell-tools/cat/.gitignore b/implement-shell-tools/cat/.gitignore
new file mode 100644
index 000000000..fd4f2b066
--- /dev/null
+++ b/implement-shell-tools/cat/.gitignore
@@ -0,0 +1,2 @@
+node_modules
+.DS_Store
diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
new file mode 100644
index 000000000..54a57404b
--- /dev/null
+++ b/implement-shell-tools/cat/cat.js
@@ -0,0 +1,17 @@
+#!/usr/bin/env node
+// cat.js — scaffold (no functionality yet)
+// Next commits will add:
+//   - basic file output
+//   - -n (number all lines)
+//   - -b (number non-blank)
+
+function main() {
+  const args = process.argv.slice(2);
+  if (args.length === 0) {
+    console.error("Usage: node cat.js <file...>");
+    process.exit(1);
+  }
+  console.log("cat: scaffold ready (implementation comes in next commit)");
+}
+
+if (require.main === module) main();

From 7addc37a2a700e0dcd5ae66c9055cc68e2b1301f Mon Sep 17 00:00:00 2001
From: Pezhman-Azizi <80008463+Pezhman-Azizi@users.noreply.github.com>
Date: Sun, 21 Sep 2025 09:14:52 +0100
Subject: [PATCH 8/8] cat: implement basic file concatenation (no flags)

---
 implement-shell-tools/cat/cat.js | 54 ++++++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 13 deletions(-)

diff --git a/implement-shell-tools/cat/cat.js b/implement-shell-tools/cat/cat.js
index 54a57404b..0112eeb0b 100644
--- a/implement-shell-tools/cat/cat.js
+++ b/implement-shell-tools/cat/cat.js
@@ -1,17 +1,45 @@
 #!/usr/bin/env node
-// cat.js — scaffold (no functionality yet)
-// Next commits will add:
-//   - basic file output
-//   - -n (number all lines)
-//   - -b (number non-blank)
+// cat.js — basic version (no flags)
 
-function main() {
-  const args = process.argv.slice(2);
-  if (args.length === 0) {
-    console.error("Usage: node cat.js <file...>");
-    process.exit(1);
-  }
-  console.log("cat: scaffold ready (implementation comes in next commit)");
+import fs from "fs";
+
+const files = process.argv.slice(2);
+
+if (files.length === 0) {
+  console.error("Usage: node cat.js <file...>");
+  process.exit(1);
 }
 
-if (require.main === module) main();
+let hadError = false;
+
+(async () => {
+  for (const file of files) {
+    try {
+      const stat = await fs.promises.stat(file);
+      if (stat.isDirectory()) {
+        console.error(`cat: ${file}: Is a directory`);
+        hadError = true;
+        continue;
+      }
+      await pipeFile(file);
+    } catch (err) {
+      if (err?.code === "ENOENT" || err?.code === "ENOTDIR") {
+        console.error(`cat: ${file}: No such file or directory`);
+      } else {
+        console.error(`cat: ${file}: ${err?.message || "Error"}`);
+      }
+      hadError = true;
+    }
+  }
+  if (hadError) process.exitCode = 1;
+})();
+
+function pipeFile(file) {
+  return new Promise((resolve, reject) => {
+    const rs = fs.createReadStream(file);
+    rs.on("error", reject);
+    rs.on("end", resolve);
+    // important: keep stdout open between files
+    rs.pipe(process.stdout, { end: false });
+  });
+}