Xmodmap syntax for rebinding Shift+Down to Up

keyboard-layoutx11xmodmap

I would like to rebind some keys on Linux via Xmodmap. Left and up cursor on my Acer (yes, I know) laptop have broke. I would like to map shift+down to up, and shift+right to left. Struggling to determine the syntax for this from man pages. This syntax is wrong, throws bad modifier, but captures the intent:

add Shift_L+Down = Up

Best Answer

You can use:

keysym Down = Down Up

to do that. The keysym value is an ordered list of keysyms to use when unmodified, shifted, switched, shifted and switched, AltGr+key, shift-AltGr+key (all optional). Here unmodified Down is itself, while Shift-Down is bound to Up, and we don't set anything for the switched or AltGr modes.

There is a remaining problem: the Shift key is still pressed, so Shift-Down will be treated by applications the same way as Shift-Up. That may not be a problem for your use cases, but if you're going to use something that, say, uses shifted arrows for text selection, you'll have a problem. In that case there is another option:

keysym Down = Down Down Up Up

That binds both Down and Shift-Down as Down, and Mode_switch-Down and Mode_switch-Shift-Down to Up. Applications are unlikely to be listening to the Mode_switch key in the same way they do to Shift, so you don't get the double behaviour.

You then need to bind something to the Mode_switch keysym. I use:

keycode 66 = Mode_switch

which, on my keyboard, replaces Caps Lock, a key I don't have a use for. Caps Lock+Down now gives me Up as far as all my applications are concerned. You could rebind one of your shift keys instead if you preferred, but you'd lose the ordinary Shift modifier behaviour when you did.

There are actually more levels you can bind if you need, which use AltGr, and depending on your layout there can be yet another set of changes available. XCompose may also be useful to you.

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xmodmap – Shift + Keycode to Produce Keysym with xmodmap

Key chords (like Shift+\) are specified by combining one key with a set of modifiers, not by combining keys directly. So rather than “keycode 50 plus keycode 21”, what you need to specify is “keycode 21 plus the Shift modifier”. Only modifiers can be used in combinations. Furthermore xmodmap is somewhat limited: you need to specify all the key chords for a particular base key at the same time.

keycode 21 = backslash grave acute

The first keysym (character or function key name) after the equal sign is the one corresponding to the bare key, then comes the one corresponding to the key with Shift, then with AltGr, then with Shift+AltGr.

If you want dead keys, then change this to

keycode 21 = backslash dead_grave dead_acute

If you want a standard Norwegian layout, though, you should be able to select it in your desktop environment's configuration interface, or with XKB — setxkbmap -layout no switches to a Norwegian layout.

“xmodmap -pke” shows more than 6 columns

Your configuration likely has virtual modifiers (a feature added about ten years ago, without completing the documentation).

They have no predefined meanings. Quoting from How to further enhance XKB configuration:

Any key type description can use both real and virtual modifiers. Since real modifiers always have standard names it is not necessary to explicitly declare them. Virtual modifiers can have arbitrary names and can be declared (prior using them) directly in key type definition:

Here are some places where it is discussed:

as well as manual pages

Best Answer

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xmodmap – Shift + Keycode to Produce Keysym with xmodmap

“xmodmap -pke” shows more than 6 columns

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