Cygwin's default user interface may be the bash shell working inside the mintty terminal emulator.[25] The DLL also implements pseudo terminal (pty) gadgets, and Cygwin ships with several terminal emulators which might be determined by them, like rxvt/urxvt and xterm. The Model of GCC that includes Cygwin has many extensions https://acgwin62952.blogscribble.com/37231814/what-does-acgwin-mean