In computing, tty is a command in Unix and Unix-like operating systems to print the file name of the terminal connected to standard input.
tty stands for "teletypewriter".
The <code>tty</code> command is commonly used to check if the output medium is a terminal. The command prints the file name of the terminal connected to standard input. If no file is detected (in case, it's being run as part of a script or the command is being piped) "<code>not a tty</code>" is printed to standard output and the command exits with an exit status of 1. The command also can be run in silent mode (<code>tty -s</code>) where no output is produced, and the command exits with an appropriate exit status.