This is based on the "Build Your Own Shell" Challenge.

This implementation provides an interactive POSIX-style shell that interprets commands, runs external programs and builtins, and exposes a REPL.

It implements a prompt and parsing, with builtins such as exit, echo, and type, and runs executables found in PATH.

Navigation: with pwd and cd(absolute, relative, and home-directory paths) commands.

Quoting: handle single quotes, double quotes, and backslash escaping.

Redirection: redirect stdout and stderr, with options to create or append files.

Background jobs: start jobs with &, list running jobs, and reap finished jobs.

Pipelines: pipe a command’s stdout to the next command’s stdin and chain multiple commands in a single pipeline.