- [X] Use /dev/ptmx, to get ptmx (master) and pts (slave) file descriptors,
then fork and exec shfx as child (+ close ptmx), then close pts as parent.
>[!NOTE]
> Use `termios(3)` to enable raw mode (implemented in `cursed.c`) (for the slave or master?)

- [ ] Implement a SIGCHLD handler instead of using `waitpid` in `killchild()`, see 2nd example in `man wait(3p)`
- [ ] Use threads to launch `killchild` to avoid blocking, then just join all the threads using atexit()