Added Topic-2

.gitignore

@@ -1,4 +1,5 @@
 #CLion
 cmake-build-debug
 CMakeLists.txt
-.idea
+.idea
+*.o

Topic-2/Makefile

@@ -0,0 +1,12 @@
+# target : source files
+task_2_1 : task_2_1.o child_functions.o
+	gcc -Wall -o task_2_1 task_2_1.o child_functions.o
+
+task_2_1.o : task_2_1.c
+	gcc -Wall -o task_2_1.c
+
+child_functions.o : child_functions.c
+	gcc -Wall -c child_functions.c
+
+clean:
+	rm -f task_2_1 task_2_1.o child_functions.o

Topic-2/child_functions.c

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+void child_task() {
+    printf("I am a child\n");
+}

Topic-2/child_functions.h

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#ifndef AAE_CNAS_LABS_CHILD_FUNCTIONS_H
+#define AAE_CNAS_LABS_CHILD_FUNCTIONS_H
+
+#include <stdio.h>
+
+void child_task();
+
+#endif //AAE_CNAS_LABS_CHILD_FUNCTIONS_H

Topic-2/task_2_1.c

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include "child_functions.h"
+
+int main() {
+    pid_t pid;
+
+    pid = fork();
+
+    if (pid == -1) {    // If something went wrong.
+        perror("Fork: ");
+        exit(EXIT_FAILURE);
+    }
+
+    if (pid == 0) {     // If this is a child process.
+        child_task();
+        exit(EXIT_SUCCESS);
+    }
+
+    printf("I am a parent.\n");
+	sleep(1); // This may be required as the parent process won't wait for the child process to finish its execution.
+	return 0;
+}

Topic-2/task_2_2.c

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void child_task() {
+    printf("I am a child\n");
+}
+
+void print_pids() {
+    printf("My PID is %d\nMy parent's PID is %d\n", getpid(), getppid());
+}
+
+int main() {
+    pid_t pid;
+
+
+
+    pid = fork();
+
+    if (pid == -1) {    // If something went wrong.
+        perror("Fork: ");
+        exit(EXIT_FAILURE);
+    }
+
+    if (pid == 0) {     // If this is a child process.
+        child_task();
+        print_pids();
+        exit(EXIT_SUCCESS);
+    }
+
+    printf("I am a parent.\n");
+    print_pids();
+    sleep(1); // This may be required as the parent process won't wait for the child process to finish its execution.
+    return 0;
+}

Topic-2/task_2_3.c

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void child_task() {
+    printf("I am a child\n");
+}
+
+void print_pids() {
+    printf("My PID is %d\nMy parent's PID is %d\n", getpid(), getppid());
+
+}
+
+void print_pids_child() {
+    printf("CHILD\nMy PID is %d\nMy parent's PID is %d\n", getpid(), getppid());
+}
+
+int main() {
+    pid_t pid;
+
+    for (int i = 0; i < 5; ++i) {
+        pid = fork();
+        if (pid == -1) {    // If something went wrong.
+            perror("Fork: ");
+            exit(EXIT_FAILURE);
+        }
+        if (pid == 0){
+            print_pids_child();
+            exit(EXIT_SUCCESS);
+        }
+    }
+
+
+    printf("I am a parent.\n");
+    print_pids();
+    sleep(1); // This may be required as the parent process won't wait for the child process to finish its execution.
+    return 0;
+}

Topic-2/task_2_4.c

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+//
+// Wrote for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+
+void parent_before_child() {
+    pid_t pid;
+    printf("parent_before_child()\n");
+    pid = fork();
+    if (pid == -1) {    // If something went wrong.
+        perror("Fork: ");
+        exit(EXIT_FAILURE);
+    }
+    if (pid != 0) {     // If this is a parent process.
+        printf("I am a parent.\n");
+        kill(getpid(), SIGKILL);
+    } else {
+        sleep(1);
+        printf("I am a child\n");   // This line will not be printed, as (usually) parent process will finish
+        // its execution in less than 1 second.
+    }
+}
+
+void child_before_parent() {
+    pid_t pid;
+    printf("child_before_parent()\n");
+    pid = fork();
+    if (pid == -1) {    // If something went wrong.
+        perror("Fork: ");
+        exit(EXIT_FAILURE);
+    }
+    if (pid == 0) {     // If this is a parent process.
+        printf("I am a child.\n");
+        kill(getpid(), SIGKILL);
+    } else {
+        sleep(1);
+        printf("I am a parent.\n");
+    }
+}
+
+int main() {
+    pid_t pid;
+    pid = fork();
+    if (pid == 0) {
+        child_before_parent();
+        sleep(1);
+        parent_before_child();
+        sleep(1);
+    }
+    sleep(5);
+    return 0;
+}