Barbara hunter

README.md

@@ -1,5 +1,7 @@
 # Processes and System Calls
 
+init....
+
 Now that we've talked a bit about how processes and system calls work at a high level, it's time to apply these concepts by doing some exercises related to process creation and making system calls. We'll be utilizing the `fork()`, `exec()`, `wait()`, and `pipe()` system calls in order to create processes and even have them pass messages to each other.
 
 ## Objective

ex1/ex1.c

@@ -9,6 +9,28 @@
 int main(void)
 {
     // Your code here
+    // init x
+    int x = 100;
+    printf("Hello there, before we call fork(), this is our processID is: (pid: %d) \n", (int)getpid());
+    printf("This is the parents value for x: %d \n", x);
+    int rc = fork();
+
+    if (rc < 0)
+    {
+        printf("Forking failed \n");
+    }
+    else if (rc == 0)
+    {
+
+        printf("Hello there, if rc==0, this is our child processID is: (pid: %d) \n", (int)getpid());
+        printf("This is the childs value for x if rc==0: %d \n", x);
+    }
+     else
+    {
+        int x = 200;
+        printf("hello, if rc > 0, this is parent here (pid: %d) of child %d\n", (int)getpid(), rc);
+        printf("This is the childs value for x if rc > 0: %d \n", x);
+    }
 
     return 0;
 }

ex2/ex2.c

@@ -9,6 +9,31 @@
 int main(void)
 {
     // Your code here 
+    FILE *fp;
+
+    fp = fopen("text.txt", "w+");
+    printf("Before forking pid: %d\n", (int)getpid());
+
+    fprintf(fp, "%s %s %s %s %d\n", "File", "write", "before", "fork", (int)getpid());
+
+    pid_t pid = fork();
+
+    if (pid < 0) //fork failed
+    {
+        exit(1);
+    }
+    else if (pid == 0) //child process
+    {
+        printf("AFTER forking CHILD pid: %d\n", (int)getpid());
+        fprintf(fp, "%s %s %d\n", "Child-File", "write", (int)getpid());
+    }
+    else
+    {
+        printf("AFTER forking PARENT pid: %d\n", (int)getpid());
+        fprintf(fp, "%s %s %d\n", "Parent-File", "write", (int)getpid());
+    }
+    fclose(fp);
+
 
     return 0;
 }

ex2/text.txt

@@ -0,0 +1,4 @@
+File write before fork 4563
+Parent-File write 4563
+File write before fork 4563
+Child-File write 4564

ex3/ex3.c

@@ -10,6 +10,23 @@
 int main(void)
 {
     // Your code here
+    printf("Before forking pid: %d\n", (int)getpid());
+
+    pid_t pid = fork();
+
+    if (pid < 0)
+    {
+        exit(1);
+    }
+    else if (pid == 0)
+    {
+        printf("AFTER forking CHILD says Hello pid: %d\n", (int)getpid());
+    }
+    else
+    {
+        waitpid(pid, NULL, 0);
+        printf("AFTER forking PARENT says Goodbye pid: %d\n", (int)getpid());
+    }
 
     return 0;
 }