The main purpose of the TTY command is to display and control text-based terminals. It provides a way for users to access a shell or other command line interface on a computer system. TTY can be used to establish connections with remote computers, run programs, monitor system processes, and transfer files. To use the TTY command, users must first open their terminal window and type in the command followed by any necessary parameters. Additionally, users should take steps to ensure that their environment is secure when using TTY as it may be vulnerable to malicious actors attempting to gain access or manipulate the system without authorization.