Processes - Evan Carlstrom

ex1/ex1.c

@@ -9,6 +9,19 @@
 int main(void)
 {
     // Your code here
+    int x = 100;
+    int pid = fork();
+
+    if(pid == 0) {
+        printf("Hello, I'm a child process!\n");
+    }
+    else {
+        printf("Hello, I'm a parent process!\n");
+    }
+    printf("%d %d", 100, x);
 
     return 0;
 }
+
+/* After initialization, the variable in the child process would be the same as its value in the parent process. When the parent and child change the value of x, we can access both values of x within their respective forks.
+If we were to do something like (x * 2) in the parent fork and (x / 2) in the child fork, we could work with both 200 and 50. */

ex2/ex2.c

@@ -9,6 +9,21 @@
 int main(void)
 {
     // Your code here 
-
+    FILE * file_pointer;
+
+    file_pointer = fopen("text.txt", "r+");
+    int pid = fork();
+
+    if(pid == 0) {
+        fprintf(file_pointer, "%s %s", "Child", "text.\n");
+        fclose(file_pointer);
+    }
+    else {
+        fprintf(file_pointer, "%s %s", "Parent", "text.");
+        fclose(file_pointer);
+    }
+
     return 0;
 }
+
+/* Yes, both child and parent can access the file returned by fopen(). In the case of concurrent attempts, they are saved together as in the example above. */

ex2/text.txt

@@ -0,0 +1 @@
+Parent text.Child text.

ex3/ex3.c

@@ -10,6 +10,15 @@
 int main(void)
 {
     // Your code here
+    int pid = fork();
+    waitpid(pid, NULL, 0); /* if I'm understanding this right, the wait(NULL) here ensures the child is printed first */
 
+    if(pid == 0) {
+        printf("%s", "hello\n");
+    }
+    else {
+        printf("%s", "goodbye\n");
+    }
+
     return 0;
 }