 A typical Linux kernel-based operating system provides many PTYs to support text-based interfaces as provided by terminal emulators (such as xterm or gnome-terminal) and remote access interfaces like SSH.In February 1998, Linux 2.1.87 brought support for the codice_2 multiplexing master device.Opening this device provides access to an otherwise unused pseudo TTY master and allows the matching slave to be identified using an ioctl().