If the function keys <F1> to <F10> do not work on your terminal
as expected, use this procedure until the problem is fixed:
press alt-1 (or <esc> 1) for <F1>
press alt-2 (or <esc> 2) for <F2>
...
press alt-9 (or <esc> 9) for <F9>
press alt-0 (or <esc> 0) for <F10>
On some systems the <Fx> keys work properly but <esc> <Fx> sequences do not work. You have to press the <esc> key twice before pressing <F1> to <F12>.