Makefile: make file

syscalls: Solve question 2

Makefile

@@ -0,0 +1,19 @@
+
+CC = gcc
+CFLAGS =
+
+OBJECTS := syscalls.o
+EXEC := syscalls
+
+.PHONY: all clean
+
+all: $(EXEC)
+
+%: %.o
+	$(CC) $(CFLAGS) -o $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+clean:
+	rm $(OBJECTS) $(EXEC)

syscalls.c

@@ -0,0 +1,40 @@
+/* +-----------------------------------------------+
+   | John Breaux - jab0910 - JohnBreaux@my.unt.edu |
+   |  syscalls.c - CSCE4600 Homework 1 Question 2  |
+   +-----------------------------------------------+ */
+
+#include <sys/wait.h> // wait()
+#include <unistd.h>   // fork(), getpid(), getppid(), execl(), exit()
+#include <stdlib.h>   // EXIT_SUCCESS
+#include <stdio.h>    // printf()
+// tabs are 3 spaces, because I find it more aesthetically pleasing than x=[1-8]|x!=3 spaces
+int main(int argc, char **argv) {
+   // First we fork, and assign the child's pid to a variable
+   int child = fork();
+   // If we have a child, then we're the parent, and must wait for the child to execute
+   if (child) {
+      // We get our own pid
+      int pid = getpid();
+      printf("[PARENT]: pid = %d, child = %d\n", pid, child);
+      // Wait for the child to exit, and acquire its status
+      int status = 0;
+      int exited_child = wait(&status);
+      printf("[PARENT]: child %d exited with status %d.\n", exited_child, status);
+      // exit
+      exit(EXIT_SUCCESS);
+   }
+   // If we have no child, we are the child, and are assigned the task of executing
+   else {
+      // Get our pid, get parent's pid
+      int pid = getpid(), parent_pid = getppid();
+      // Print that information
+      printf("[CHILD ]: pid = %d, parent_pid = %d\n", pid, parent_pid);
+      // Hand control over to ls, with the arguments "-la"
+      char *command = "/bin/ls", *argv1 = "-la";
+      printf("[CHILD ]: execl(%s, %s, NULL);\n", command, argv1);
+      // execl takes the command, the arguments, and a null-pointer terminator argument
+      // argv[0] is the path to the command, argv[1] is the first argument
+      // personally I prefer execv()/execve() for their relative ease of use
+      execl(command, command, argv1, (char*)NULL);
+   }
+}