As admin i want to block the clipboard access in Linux GUI. No user can copy data from terminal or other thing. In simple terms it means just block the copy option.
I don't expect you'd be be able to easily disable the X selection mechanism, but you could start a process that connects to every X server that steals the selections (and empty the
CUT_BUFFER0) every time a process tries to own them. Here using
xprop utilities, though you'd probably want to write a program that does the equivalent to make it more lightweight (especially if using a clipboard manager that would try and constantly steal back the CLIPBOARD selection off you).
for sel in clipboard primary secondary; do while xclip -i -sel "$sel" -q; do xprop -root -format CUT_BUFFER0 8s -set CUT_BUFFER0 '' done & done <> /dev/null >&0 2>&0