enhance - enhanced command-line editing facilities
enhance command [argument]...
The enhance program provides enhanced command-line editing facilities to users of third party applications, to which one doesn't have any source code. It does this by placing a pseudo-terminal between the application and the real terminal. It uses the tecla command-line editing library to read input from the real terminal, then forwards each just completed input line to the application via the pseudo-terminal. All output from the application is forwarded back unchanged to the real terminal.
Whenever the application stops generating output for more than a tenth of a second, the enhance program treats the latest incomplete output line as the prompt, and re-displays any incompleted input line that the user has typed after it. The small delay, which is imperceptible to the user, isn't necessary for correct operation of the program. It is just an optimization, designed to stop the input line from being re-displayed so often that it slows down output.
The user-level command-line editing facilities provided by the Tecla library are documented in the tecla(5) man page
The one major problem that hasn't been solved yet, is how to deal with applications that change whether typed input is echo'd by their controlling terminal. For example, programs that ask for a password, such as ftp and telnet, temporarily tell their controlling terminal not to echo what the user types. Since this request goes to the application side of the pseudo terminal, the enhance program has no way of knowing that this has happened, and continues to echo typed input to its controlling terminal, while the user types their password.
Furthermore, before executing the host application, the enhance program initially sets the pseudo terminal to noecho mode, so that everything that it sends to the program doesn't get redundantly echoed. If a program that switches to noecho mode explicitly restores echoing afterwards, rather than restoring the terminal modes that were previously in force, then subsequently, every time that you enter a new input line, a duplicate copy will be displayed on the next line.
tecla personal customization file.
See attributes(5) for descriptions of the following attributes: