xfce4-terminal doesn't provide a facility for {in,de}creasing font
size in a running terminal. However, xfce4-terminal does watch the
file $XDG_CONFIG_PATH/xfce4/terminal/terminalrc for changes to the
FontName directive (which includes size).
Therefore, this script can be bound to a via a keyboard shortcut that will change the font size, albeit after a short delay.
No thanks to urxvt-unicode for not supporting fontconfig, which is
necessary to run an unpatched Monaco font in Powerline, which I must
have, all of which prompted my switch to xfce4-terminal which does
support fontconfig and ... oh, nevermind.
To use it,
% ./xfce4-terminal +
% ./xfce4-terminal -
% ./xfce4-terminal
12
% ./xfce4-terminal 7.5
In Awesome,
awful.key({ "Control", "Shift" }, "Up", function () awful.util.spawn(script_dir .. "/xfce4-terminal-font +", false)end),
awful.key({ "Control", "Shift" }, "Down", function () awful.util.spawn(script_dir .. "/xfce4-terminal-font -", false)end), })})