Minishell

Basic implementation of a shell, bash like, in c

Subject

Your shell should:

• 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 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 metacharacters in the quoted sequence.
• Handle double quote which should prevent the shell from interpreting the metacharacters 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 thedelimiter 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.

Skills

Thanks to this project, I learned how to handle a lot of file descriptors and how to manage multiprocessing.