Cygwin's default person interface is the bash shell running in 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://acgwin31741.bligblogging.com/37809501/getting-my-acgwin-to-work