Writing a Unix Shell
FWIW I wrote a pretty complete shell in ~11K lines of Python:<p><a href="https:&#x2F;&#x2F;github.com&#x2F;oilshell&#x2F;oil" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;oilshell&#x2F;oil</a> (osh&#x2F; and core&#x2F; directories):<p>Right now the goal is to clone bash but have better parse time and runtime errors.  I hope to make an initial release this summer.  But the project is much larger (see the blog if interested).