Update and rename e to shell.h

ShellBuiltins/shell.h

@@ -0,0 +1,51 @@
+
+int SHa_cd(char **args);
+int SHa_help(char **args);
+int SHa_exit(char **args);
+char *builtin_str[] = {
+  "cd",
+  "help",
+  "exit"
+};
+
+int (builtin_func[]) (char *) = {
+  &SHa_cd,
+  &SHa_help,
+  &SHa_exit
+};
+
+int SHa_num_builtins() {
+  return sizeof(builtin_str) / sizeof(char *);
+}
+
+int SHa_cd(char **args)
+{
+  if (args[1] == NULL) {
+    fprintf(stderr, "SHa: expected argument to \"cd\"\n");
+  } else {
+    if (chdir(args[1]) != 0) {
+      perror("SHa");
+    }
+  }
+  return 1;
+}
+
+int SHa_help(char **args)
+{
+  int i;
+  printf("Stephen Brennan'SHa\n");
+  printf("Type program names and arguments, and hit enter.\n");
+  printf("The following are built in:\n");
+
+  for (i = 0; i < SHa_num_builtins(); i++) {
+    printf("  %s\n", builtin_str[i]);
+  }
+
+  printf("Use the man command for information on other programs.\n");
+  return 1;
+}
+
+int SHa_exit(char **args)
+{
+  return 0;
+}