Processes Exercises

ex1/ex1.c

@@ -10,5 +10,26 @@ int main(void)
 {
     // Your code here
 
+    int x = 100;
+
+    int rc = fork();
+
+    if (rc < 0) {
+    	printf("Fork failed...\n");
+    } else if (rc == 0) {
+    	// child returns 0 to fork...
+    	printf("The value of x in child is %d.\n", x);
+
+    	x = 101;
+
+    } else {
+    	// parent returns child's PID -> getpid()
+    	printf("The value of x in parent is %d.\n", x);
+
+    	x = 102;
+    }
+
+    printf("The final value of x is %d\n", x);
+
     return 0;
 }

ex2/ex2.c

@@ -9,6 +9,33 @@
 int main(void)
 {
     // Your code here 
+	FILE *fp;
+	int c;
+
+    fp = fopen("text.txt", "r+");
 
+    int rc = fork();
+
+    if (rc < 0) {
+    	printf("Fork failed...\n");
+    } else if (rc == 0) {
+    	fprintf(fp, "This is the child.\n");
+    } else {
+    	fprintf(fp, "This is the parent.\n");
+    }
+
+    while(1) {
+
+    	c = fgetc(fp);
+
+    	if (feof(fp)) {
+    		break;
+    	}
+    	printf("%c", c);
+    }
+    printf("\n");
+
+    fclose(fp);
+
     return 0;
 }

ex2/text.txt

@@ -0,0 +1,6 @@
+This is the parent.
+This is the child.
+This is the child.
+This is the child.
+This is the child.
+This is the child.

ex3/ex3.c

@@ -10,6 +10,16 @@
 int main(void)
 {
     // Your code here
+	int rc = fork();
+
+	if (rc < 0) {
+		printf("Fork failed...\n");
+	} else if (rc == 0) {
+		printf("hello\n");
+	} else {
+		waitpid(rc, NULL, 0);
+		printf("goodbye\n");
+	}
 
     return 0;
 }

ex4/ex4.c

@@ -7,10 +7,26 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <sys/wait.h>
+#include <string.h>
 
-int main(void)
+int main(int argc, char *argv[])
 {
-    // Your code here    
+    // Your code here  
+    int rc = fork();
+
+
+    if (rc < 0) {
+    	printf("Fork failed...\n");
+    } else if (rc == 0) {
+
+    	char *my_args[3];
+
+    	my_args[0] = strdup("/bin/ls");
+    	my_args[1] = strdup("ex4.c");
+    	my_args[1] = NULL;
+
+    	execvp(my_args[0], my_args);
+    }
 
     return 0;
 }

ex5/ex5.c

@@ -17,6 +17,38 @@ char* msg3 = "hello world #3";
 int main(void)
 {
     // Your code here
+	char inbuf[MSGSIZE];
+	int p[2];
+
+	if (pipe(p) < 0) {
+    	fprintf(stderr, "pipe failed...\n");
+    	exit(1);
+    }
+
+    int rc = fork();
+
+    if (rc < 0) {
+    	printf("fork failed...\n");
+    } else if (rc == 0) {
+    	close(p[0]);
+    	write(p[1], msg1, MSGSIZE);
+    	write(p[1], msg2, MSGSIZE);
+    	write(p[1], msg3, MSGSIZE);
+    	close(p[1]);
+    } else {
+
+    	waitpid(rc, NULL, 0);
+
+    	close(p[1]);
+
+    	for (int i = 0; i < 3; i++) {
+
+    		read(p[0], inbuf, MSGSIZE);
+    		printf("%s\n", inbuf);
+    	}
+
+    	close(p[0]);
+    }
 
     return 0;
-}
+}