- open(), close(), read(), write(), lseek()
- fopen(), fclose(), fscanf(), fprintf()
- fread(), fwrite()
- Dynamic Allocation
- Shared Memory
- exec
- execlp(), execv(), execve()
- fork()
- Number Counting
- Basic TCP
- Basic UDP
- Loop Server
- Fork Server
- Thread Server
interface_addr interface_info stat
- errno & perror()
- syscall()