A small shell like bash with pure C++,based on flex, bison and readline.

Support:

• external cmd.
• internal cmd: cd,exit,job,kill,echo,exec.
• pipeline/redirection.
• multicmd per line. separated by ';'.
• background task. with '&'
• simple task management: job kill
• ctrl+c interrupt foreground task.
• 'exit' exit the Yinsh.