If you are on a Linux console, for example, some key combinations might simply not exist – it depends on the setup outside of Emacs.
For example there is no C-<up>, C-<right>, C-<down>, C-<left>, etc. on my Linux console by default. Therefore I created a .keymap file with the following entries (amonst others):
# control up down left right home end control keycode 103 = Meta_p control keycode 108 = Meta_n control keycode 105 = Meta_Control_b control keycode 106 = Meta_Control_f control keycode 102 = Meta_less control keycode 107 = Meta_greater # C-TAB should be like M-/ (dabbrev-expand) control keycode 15 = Meta_slash # CapsKey should be like C-_ (undo) keycode 58 = Control_underscore
And it is used in my .profile:
# If console, change some keymaps if [ $TERM = 'linux' -a -x /usr/bin/loadkeys -a -f .keymap ] ; then loadkeys de-latin1 2> /dev/null loadkeys .keymap 2> /dev/null fi
See LoadKeys for more information about the programs used.
‘showkey’ and type the key you want.