1 Functionality of system calls:
2 - Test argument passing on Pintos command line.
9 - Test "create" system call.
15 - Test "open" system call.
20 - Test "read" system call.
24 - Test "write" system call.
28 - Test "close" system call.
31 - Test "exec" system call.
36 - Test "wait" system call.
40 - Test "exit" system call.
43 - Test "halt" system call.
46 - Test recursive execution of user programs.
49 - Test read-only executable feature.