almost got the term emu working and shell

rocklibc/include/syscall.h

@@ -7,9 +7,14 @@
 #define SYS_EXIT    1
 #define SYS_READ    3
 #define SYS_WRITE   4
+#define SYS_OPEN    5
+#define SYS_CLOSE   6
 #define SYS_PTY     20
 #define SYS_FORK    21
+#define SYS_EXEC    22
+#define SYS_DUP2    23
 
+int open(const char* path);
 int write(int fd, const void *buf, size_t count);
 int read(int fd, void *buf, size_t count);
 int close(int fd);
@@ -22,6 +27,9 @@ void *sbrk(intptr_t increment);
 int brk(void *addr);
 
 int pty(int* slave);
+
 int fork();
+int exec(const char* path);
+int dup2(int src, int dst);
 
 #endif