Wish (Unix shell)

(Windowing Shell) is a Tcl interpreter extended with Tk commands, available for Unix-like operating systems supporting the X Window System, as well as macOS, Microsoft Windows, and Android. It provides developers the ability to create GUI widgets using the Tk toolkit and the Tcl programming language.

is open-source under the BSD License, and is currently part of the Tcl/Tk programming suite.

Usage
can be run without parameters. Then the  prompt is displayed and the interpreter awaits for commands entered interactively by the user. An empty window is opened in which the widgets created by user commands are displayed. This mode is suitable for experimenting.

More often  is run with a name of a file containing a Tcl/Tk script as a parameter. It is also possible to run directly Tcl/Tk scripts; in Unix using the shebang construction; in Windows by associating the  extension with the wish program.