Cygwin's default person interface is the bash shell operating within the mintty terminal emulator.[25] The DLL also implements pseudo terminal (pty) devices, and Cygwin ships with numerous terminal emulators which are according to them, which includes rxvt/urxvt and xterm. The Edition of GCC that comes with Cygwin has numerous extensions https://acgwin63952.blogtov.com/17602193/helping-the-others-realize-the-advantages-of-acgwin