A button can be created in the following way:
% button .b -text "My first button" .b
button is the command for creating a button widget, .b is the
path or the name of the button (more about paths later). The
arguments -text "My first button" tell Tk to put the string "My first
button" in the button.
Now we tell Tk to put this button in the main window:
% pack .bAnd voilà, a button appears in the main window with the text "My first button". Pressing the button won't do anything, because we haven't told Tk what to do when the button is pressed. We can do that in the following way:
% .b configure -command { puts "My first button has been pressed" }
Pressing the button will now result in printing the string "My first button
has been pressed". We have bound the command
puts "My first button has been pressed" to the "push button" event.