- cwd.c
- handle current directory (cd)
- execute.c
- process management
- lexer.c
- Lexical Analyzer
- parser.y
- Yacc(Bison)
- rubbish.c
- read inputs by readline()
- manage input historys
- rubgc.c
- memory management
- semantic.c
- functions that generate abstract syntax
- shellcmd.c
- internal shell commands