Structure basic of UNIX system have 4 part is Hardware , Kernel , Shell and Application show in fig 1.
![Unix Architecture](https://pongpat.janthai.com/wp-content/uploads/2013/04/UNIX-Structure.jpg)
Shell is a program on UNIX system. Shell officiate interface between User and UNIX (Kernel) . User can cammand UNIX via Shell only one. Shell program have property of shell programming language ,User can using commands include a file call “Shell Script”.