if we want to add other functions and applications…

• [ ] split shell in another file
• [ ] parsing arguments from shell
• [ ] more about printf
• [ ] scanf
• [ ] ls
• [ ] echo
• [ ] touch
• [ ] cat
• [ ] find
• [ ] tree
• [ ] mkdir
• [ ] rmdir
• [ ] rm
• [ ] sbrk
• [ ] malloc
• [ ] free
• [ ] fork
• [ ] exec
• [ ] wait