diff --git a/OS/bash/Week4/q2.sh b/OS/bash/Week4/q2.sh
new file mode 100644
index 0000000..c99057c
--- /dev/null
+++ b/OS/bash/Week4/q2.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+echo "Deleteing the following files"
+
+for file in "$@";do
+echo "$file"
+rm -i "$file"
+done
+
+echo "All files deleted successfully"
diff --git a/OS/bash/Week4/q3.sh b/OS/bash/Week4/q3.sh
new file mode 100644
index 0000000..4f9ac45
--- /dev/null
+++ b/OS/bash/Week4/q3.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+
+selection_sort()
+{
+    local arr=("$@") # array declaration
+    local n=${#arr[@]}
+
+    for ((i=0; i<n-1; i++)); do
+        min=$i
+        for ((j=i+1; j<n; j++)); do
+            if [[ ${arr[j]} < ${arr[min]} ]]; then
+                min=$j
+            fi
+        done
+
+        temp="${arr[min]}"
+        arr[min]="${arr[i]}"
+        arr[i]="$temp"
+    done
+
+    for element in "${arr[@]}"; do
+        echo "$element"
+    done
+}
+
+selection_sort "$@"
diff --git a/OS/bash/Week4/q4.sh b/OS/bash/Week4/q4.sh
new file mode 100644
index 0000000..0847eeb
--- /dev/null
+++ b/OS/bash/Week4/q4.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+
+opt="$1"
+file="$2"
+
+case "$opt" in
+	-linecount)
+		result=$(wc -l < "$file")
+		echo "Line count in $file: $result"
+		;;
+	-wordcount)
+		result=$(wc -w < "$file")
+		echo "Word count in $file: $result"
+		;;
+	-charcount)
+		result=$(wc -c < "$file")
+		echo "Character count in $file: $result"
+		;;
+	*)
+        echo "Invalid option. Please use -linecount, -wordcount, or -charcount."
+        exit 1
+        ;;
+esac
+
diff --git a/OS/bash/Week4/q5.sh b/OS/bash/Week4/q5.sh
new file mode 100644
index 0000000..acd1bce
--- /dev/null
+++ b/OS/bash/Week4/q5.sh
@@ -0,0 +1,38 @@
+#!/bin/bash
+
+num_patterns=$(( $# ))
+patterns=("${@:1:num_patterns}")
+input_file="${!num_patterns}"
+
+
+while true;do
+    echo "a. Search the patterns in the given input file."
+    echo "b. Delete all occurrences of the pattern in the given input file."
+    echo "c. Exit"
+
+    read choice
+
+    case "$choice" in
+        a)
+            echo "Searching patterns in $input_file:"
+            for pattern in "${patterns[@]}"; do
+                grep "$pattern" "$input_file"
+            done
+            ;;
+        b)
+            echo "Deleting occurrences of patterns in $input_file:"
+            for pattern in "${patterns[@]}"; do
+                sed -i "s/$pattern//g" "$input_file"
+            done
+            echo "Occurrences deleted."
+            ;;
+        c)
+            echo "Exiting..."
+            exit 0
+            ;;
+        *)
+            echo "Invalid choice. Please enter 'a', 'b', or 'c'."
+            ;;
+    esac
+
+done
diff --git a/OS/bash/Week4/solutions.md b/OS/bash/Week4/solutions.md
new file mode 100644
index 0000000..df8bc50
--- /dev/null
+++ b/OS/bash/Week4/solutions.md
@@ -0,0 +1,10 @@
+## Lab 4
+
+### Lab Exercises
+Q1. `q1.sh` - Duplication - `cp` of `$1` arg (first argument).
+Q2. `q2.sh` - Deletion - `rm` of all `$@` files using `for` loop.
+Q3. `q3.sh` - String Sort - Selection sort using loops and `if` and `echo`.
+Q4. `q4.sh` - File TypeCounter - Word/Line/CharCount of file via switch `case` statement and passing various commands.
+Q5. `q5.sh` - Pattern Recognition - `grep` for finding the pattern, `sed` for deleting the pattern, and `exit` for killing the pattern.
+
+