Could not find stack trace (printed to stderr) when child process fail.
Currently adding this code (after fork) will help debug.
                   let pid = process::id();                                                                   
                    let mut file = File::create(format!("{}.txt", pid)).unwrap();              
                    let fd = file.as_raw_fd();                                                                
                    dup2(fd, 2);                                          


Investigating a good solution.