What is (what does) a shell?
- a shell is a macro processor that executes commands
- a shell provides internal commands
- a shell provides control structures to combine programs
- a shell works in the following manner:
- Read the input
- Break the input into words and operators
- Parse the tokens into simple and compound commands
- Perform the various shell expansions
- Perform any necessary redirections
- Execute the command
- Optionally wait for the command to complete and collect its exit status