[SOLVED]Switching Caps Lock with Shift_L

Question

I have a broken left shift key, and it's a bit of a pain to type with. I often use an external keyboard, so this doesn't always bother me, but when I take my laptop with me somewhere, I would like to be able to quickly swap Caps and Left Shift. For a while, I've done that like this:
xmodmap -e "keycode 66 = Shift_L NoSymbol Shift_L"
But xmodmap is deprecated, and causing problems with qt5 applications, so I want to ditch it and do the same thing with setxbmap instead. Now, xkb is really nice, it is full of built in options for common remaps, and a quick look around shows my I can use any one of these to change how caps lock works:
grp:caps_switch Caps Lock (while pressed), Alt+Caps Lock does the original capslock action
grp:caps_toggle Caps Lock
grp:shift_caps_toggle Shift+Caps Lock
grp:shift_caps_switch Caps Lock (to first layout), Shift+Caps Lock (to last layout)
grp:alt_caps_toggle Alt+Caps Lock
lv3:caps_switch Caps Lock
lv3:caps_switch_latch Caps Lock chooses 3rd level, acts as onetime lock when pressed together with another 3rd-level-chooser
ctrl:nocaps Caps Lock as Ctrl
ctrl:swapcaps Swap Ctrl and Caps Lock
grp_led:caps Caps Lock
caps Caps Lock key behavior
caps:internal Caps Lock uses internal capitalization. Shift "pauses" Caps Lock
caps:internal_nocancel Caps Lock uses internal capitalization. Shift doesn't affect Caps Lock
caps:shift Caps Lock acts as Shift with locking. Shift "pauses" Caps Lock
caps:shift_nocancel Caps Lock acts as Shift with locking. Shift doesn't affect Caps Lock
caps:capslock Caps Lock toggles normal capitalization of alphabetic characters
caps:numlock Make Caps Lock an additional Num Lock
caps:swapescape Swap ESC and Caps Lock
caps:escape Make Caps Lock an additional ESC
caps:backspace Make Caps Lock an additional Backspace
caps:super Make Caps Lock an additional Super
caps:hyper Make Caps Lock an additional Hyper
caps:shiftlock Caps Lock toggles Shift so all keys are affected
caps:none Caps Lock is disabled
caps:ctrl_modifier Make Caps Lock an additional Control but keep the Caps_Lock keysym
compose:caps Caps Lock
compose:caps-altgr 3rd level of Caps Lock
shift:breaks_caps Shift cancels Caps Lock
shift:both_capslock Both Shift-Keys together toggle Caps Lock
shift:both_capslock_cancel Both Shift-Keys together activate Caps Lock, one Shift-Key deactivates
None of those allow me to use caps lock as a normal shift. I'm trying to figure out how to rebind caps to work as a shift, but I want to have this in a script so that my external keyboard will stick with its default behavior, and I can just type "fixshift" when I unplug it. Basically, just manually switch the two with setxkbmap the way I did with xmodmap. Out of a long while searching, and /only/ finding advice to use one of the default options, and none on making my own, I've decided to come here.
Any help, Arch-friends?
Last edited by Kebertx (2013-10-31 09:10:14)

Answer 1

For the record, here's my solution:
This creates a custom key symbol to swap Caps and Shift:
/usr/share/X11/xkb/symbols/custom
partial modifier_keys
xkb_symbols "swapcaps" {
replace key <CAPS> { [ Shift_L ] };
replace key <LFSH> { [ Caps_Lock ] };
This script prints a description of the keymap, adds the symbol to swap the two keys from that other file to the right line, and writes the new description to a temporary file... then compiles it!
/usr/local/bin/fixshift
#!/usr/bin/bash
setxkbmap -print | sed '/xkb_symbols/ { s/"/+custom(swapcaps)"/2 }' > /tmp/fixshift
xkbcomp /tmp/fixshift $DISPLAY > /dev/null 2>&1 &
Then I just set that program to run every time lightdm starts a session:
/etc/lightdm/lightdm.conf
display-setup-script=/usr/local/bin/fixshift
greeter-setup-script=/usr/local/bin/fixshift
session-setup-script=/usr/local/bin/fixshift
And nothing more to it. Life is grand again.