From d46358f2dadf3578695a12f461eef52938638bf7 Mon Sep 17 00:00:00 2001
From: sherlock <git@aaditagrawal.com>
Date: Fri, 11 Apr 2025 15:22:22 +0530
Subject: [PATCH] Added Endsem Questions

---
 OS/endsem/bashq.sh |  48 ++++++++++++++++++
 OS/endsem/cq.c     | 121 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 169 insertions(+)
 create mode 100644 OS/endsem/bashq.sh
 create mode 100644 OS/endsem/cq.c

diff --git a/OS/endsem/bashq.sh b/OS/endsem/bashq.sh
new file mode 100644
index 0000000..2d81ab7
--- /dev/null
+++ b/OS/endsem/bashq.sh
@@ -0,0 +1,48 @@
+#!/bin/bash
+
+# Ask for the directory
+echo "Enter directory path:"
+read dir
+
+while true; do
+    echo ""
+    echo "Menu:"
+    echo "1. Convert .txt files to .py in $dir"
+    echo "2. List ownership properties (ls -l) of all files in $dir"
+    echo "3. Count .sh files and subdirectories in $dir"
+    echo "4. Exit"
+    echo -n "Choose an option: "
+    read option
+
+    case $option in
+        1)
+            for file in "$dir"/*.txt; do
+                if [ -f "$file" ]; then
+                    new="${file%.txt}.py"
+                    mv "$file" "$new"
+                    echo "Renamed: $file -> $new"
+                fi
+            done
+            ;;
+        2)
+            ls -l "$dir"
+            ;;
+        3)
+            # Count .sh files in the given directory (errors hidden if none found)
+            sh_count=$(ls -1 "$dir"/*.sh 2>/dev/null | wc -l)
+            # Count subdirectories (using a trailing slash pattern)
+            dir_count=$(ls -d "$dir"/*/ 2>/dev/null | wc -w)
+            echo ".sh file count: $sh_count"
+            echo "Subdirectory count: $dir_count"
+            ;;
+        4)
+            echo "Exiting..."
+            break
+            ;;
+        *)
+            echo "Invalid option. Please try again."
+            ;;
+    esac
+done
+
+echo "Bye!"
diff --git a/OS/endsem/cq.c b/OS/endsem/cq.c
new file mode 100644
index 0000000..0aaf784
--- /dev/null
+++ b/OS/endsem/cq.c
@@ -0,0 +1,121 @@
+#include <stdio.h>
+#include <pthread.h>
+#include <limits.h>
+#define MAX_PROC 10
+#define MAX_REF 100
+#define MAX_FRAMES 10
+
+typedef struct {
+    int id;               // Process ID
+    int frames;           // Number of frames for this process
+    int n;                // Number of page references
+    int ref[MAX_REF];     // Array of page references
+    int faults;           // Page faults counter
+} Process;
+
+Process procs[MAX_PROC];
+int proc_count = 0;
+
+void *simulateOptimal(void *arg) {
+    Process *p = (Process *)arg;
+    int frameArr[MAX_FRAMES];
+    int i, j;
+
+    // Initialize frames as empty (-1)
+    for (i = 0; i < p->frames; i++) {
+        frameArr[i] = -1;
+    }
+    p->faults = 0;
+
+    // Process each page reference
+    for (i = 0; i < p->n; i++) {
+        int page = p->ref[i];
+        int found = 0;
+        // Check if page is already in a frame
+        for (j = 0; j < p->frames; j++) {
+            if (frameArr[j] == page) {
+                found = 1;
+                break;
+            }
+        }
+        if (found)
+            continue;
+        // Page fault occurs
+        p->faults++;
+
+        // Look for an empty frame (-1)
+        int empty = -1;
+        for (j = 0; j < p->frames; j++) {
+            if (frameArr[j] == -1) {
+                empty = j;
+                break;
+            }
+        }
+        if (empty != -1) {
+            frameArr[empty] = page;
+            continue;
+        }
+
+        // No empty frame; choose a victim using Optimal algorithm:
+        int replace = 0, farthest = -1;
+        for (j = 0; j < p->frames; j++) {
+            int k, nextUse = INT_MAX;
+            for (k = i + 1; k < p->n; k++) {
+                if (frameArr[j] == p->ref[k]) {
+                    nextUse = k;
+                    break;
+                }
+            }
+            if (nextUse > farthest) {
+                farthest = nextUse;
+                replace = j;
+            }
+        }
+        frameArr[replace] = page;
+    }
+
+    printf("Process %d: Faults = %d\n", p->id, p->faults);
+    return NULL;
+}
+
+int main() {
+    int i, j;
+    pthread_t threads[MAX_PROC];
+
+    // Input the number of processes
+    printf("Enter number of processes (max %d): ", MAX_PROC);
+    scanf("%d", &proc_count);
+    if (proc_count > MAX_PROC) proc_count = MAX_PROC;
+
+    // Input process details
+    for (i = 0; i < proc_count; i++) {
+        procs[i].id = i + 1;
+        printf("\nProcess %d:\n", procs[i].id);
+        printf("Enter number of frames (max %d): ", MAX_FRAMES);
+        scanf("%d", &procs[i].frames);
+        if (procs[i].frames > MAX_FRAMES) procs[i].frames = MAX_FRAMES;
+        printf("Enter number of page references (max %d): ", MAX_REF);
+        scanf("%d", &procs[i].n);
+        if (procs[i].n > MAX_REF) procs[i].n = MAX_REF;
+        printf("Enter %d page references (space separated): ", procs[i].n);
+        for (j = 0; j < procs[i].n; j++) {
+            scanf("%d", &procs[i].ref[j]);
+        }
+    }
+
+    // Create a thread for each process simulation
+    for (i = 0; i < proc_count; i++) {
+        pthread_create(&threads[i], NULL, simulateOptimal, &procs[i]);
+    }
+
+    int totalFaults = 0;
+    // Wait for all threads to complete
+    for (i = 0; i < proc_count; i++) {
+        pthread_join(threads[i], NULL);
+        totalFaults += procs[i].faults;
+    }
+
+    // Calculate and display average faults
+    printf("\nAverage Page Faults: %.2f\n", (float)totalFaults / proc_count);
+    return 0;
+}