xset s off vs xset -dpms: Do you need both?
On Linux (especially XFCE, GNOME, or other X11 desktops), if you want to keep your monitors from auto-sleeping while still being able to manually turn them off with a hotkey, you'll see these two commands recommended:
xset s off
xset -dpms
Do you need both? Usually not—but it doesn't hurt. Here's the difference:
xset -dpms controls the monitor power management (hardware sleep). This is the main one you want—it prevents the monitor from entering standby/suspend/off automatically.
xset s off controls the X11 screen saver (software blanking). In modern desktops, the screen saver usually just triggers DPMS anyway, so this often feels redundant. But it's a good safety layer to prevent "blank screen but not actually sleeping" behavior on some setups.
The practical setup
To never auto-sleep, but still allow manual off/on:
xset s off # Disable screen saver blanking
xset -dpms # Disable DPMS power saving
Then bind this to a hotkey to turn monitors off:
xset dpms force off
Moving the mouse or pressing any key wakes them back up, and they stay awake afterward (because DPMS stays disabled).
XFCE note
Don't forget to also disable display power management in: Settings → Power Manager → Display
Otherwise XFCE might re-enable DPMS behind your back.