Remap CapsLock as Ctrl

For sway, the remapping can be directly realized by inserting following entry in ~/.config/sway/config.

input type:keyboard {
      xkb_options ctrl:nocaps
}

For KDE, the transformation can be directly finished in the system settings. Enter Input Devices -> Keyboard -> Advanced, and tick the radio Caps Lock is also a Ctrl in Caps Lock behavior and Caps Lock as Ctrl in Ctrl position.

For Gnome, it is extremely easy to turn CapsLock into an additional Ctrl. Install package gnome-tweak-tool, e.g.

pacman -S gnome-tweak-tool

and configure it in the installed Tweak Tool. Enter Keyboard & Mouse -> Keyboard -> Additional Layout Options -> Caps Lock behavior and tick the radio Make Caps Lock an additional Ctrl.

xmodmap is a utility for remapping keys in Xorg. To turn CapsLock into another Ctrl, install package xorg-xmodmap, e.g.

pacman -S xorg-xmodmap

and create ~/.Xmodmap with its contents as follows.

clear lock
clear control
add control = Caps_Lock Control_L Control_R
keycode 66 = Control_L

For display manager, e.g. GDM, KDM, XDM, based startup, that is all. For startx-based, add a following entry in ~/.xinitrc.

[[ -f ~/.Xmodmap ]] && xmodmap ~/.Xmodmap