Building a Shell

9 hours ago

The author builds a toy shell named 'andsh' to understand shell internals better.
The shell supports basic commands like 'cd', 'pwd', 'echo', and external commands via 'execvp'.
Built-in commands like 'cd' must run in the shell process to affect the parent shell's state.
Environment variable expansion is implemented for variables like '$HOME' and '$?'.
Piping is supported using 'pipe()' and 'dup2()' to connect commands like 'printf abc | tr a-z A-Z | rev'.
The shell uses the 'readline' library for line editing, history, and tab completion.
Key missing features include quoting, redirection, and more built-in commands.
The project is available on GitHub at healeycodes/andsh.

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