This project is a simplified shell. It was written in C and we were limited in the functions we were allowed to use.
The requirements were:
- Display a prompt when waiting for a new command.
- Have a working history.
- Search and launch the right executable (based on the PATH variable or using a relative or an absolute path).
- Not use more than one global variable. Think about it. You will have to explain its purpose.
- Not interpret unclosed quotes or special characters which are not required by the subject such as \ (backslash) or ; (semicolon).
- Handle ’ (single quote) which should prevent the shell from interpreting the meta- characters in the quoted sequence.
- Handle " (double quote) which should prevent the shell from interpreting the meta- characters in the quoted sequence except for $ (dollar sign).
- Implement redirections:
- '<' should redirect input.
- '>' should redirect output.
- '<<' should be given a delimiter, then read the input until a line containing the delimiter is seen. However, it doesn’t have to update the history!
- '>>' should redirect output in append mode.
- Implement pipes (| character). The output of each command in the pipeline is connected to the input of the next command via a pipe.
- Handle environment variables ($ followed by a sequence of characters) which should expand to their values.
- Handle $? which should expand to the exit status of the most recently executed foreground pipeline.
- Handle ctrl-C, ctrl-D and ctrl-\ which should behave like in bash.
- In interactive mode:
- ctrl-C displays a new prompt on a new line.
- ctrl-D exits the shell.
- ctrl-\ does nothing.
- Your shell must implement the following builtins:
- echo with option -n
- cd with only a relative or absolute path
- pwd with no options
- export with no options
- unset with no options
- env with no options or arguments
- exit with no options
Other project partner: