User interface in wide sense. Command line interface. Graphical user interface. Text user interface. Cshell, zshell, bash, powershell Interact with unix kernel Term process in computing How does shell manage commands Shell algorithm (reading, interpreting, execution of the command) Shell builtins How to run external programme in separate process? Pros and cons of builtins and external programs? How to create a new process in shell? Daemon process? What shell features are needed first of all? What does prompt stand for? Difference between shell, terminal and console? What are the environmental variables and how shell interact with them? What is POSIX? What does C standard library for POSIX system consist of? Exotic shells.

And now it's fine.