ie: when running latex using Ayi's command runner, latex encounter an invalid syntax and I hit ctrl+c to stop. It seems Ayi has excited, but latex is still running, because when you enter other command you will see latex's error message

$ Type <return> to proceed, S to scroll future error messages,
R to run without stopping, Q to run quietly,
I to insert something, E to edit your file,
1 or ... or 9 to ignore the next 1 to 9 tokens of input,
H for help, X to quit.
?

I guess os/exec start a new process using fork+exec style, and that process is a child process, when ctrl+c terminate the parent process, it does not send any signal to the child, so it can not be reaped? or just silently runs in background?