Using dconf-editor, if you have already tried the xmodmap way, tried this one … it’s superior because the xmodmap will fail (and need to be rerun) after you change the keyboard layout, furthermore, it has no currently reliable way to start it on login or after boot.

So, let’s get started, if you don’t have one:

sudo apt install dconf-editor

Open it up, and see the org.gnome.desktop.input-sources.xkb-options, you might see [] for now, but update it to ['ctrl:swap_lalt_lctl','ctrl:swap_ralt_rctl']. categories: dev

You should see the effect immediately.

Furthermore, you might have problem with alt+tab (now currently is ctrl+tab), if you want to change to ctrl+tab, just to keep it matched with the physical alt, read on.

Change Alt + Tab to Ctrl + Tab

It turns out even you have the unity-tweak-tool it’s not at all straightforward to change this, because the tool won’t allow you to bind ctrl+tab actually it won’t allow even alt+tab, I think it’s a bug or the app has no privilege to intercept the alt+tab itself.

So, another way is through the compizconfig-settings-manager, if you don’t have it just install.

In it, you should find the Ubuntu Unity Plugin section, go to Switcher.

Now update it to be as follows, see the Key to start the switcher is now set to <Control>Tab: categories: dev

If you want to also change the shortcut for switching windows in the same app (which default is alt + grave accent), you may change it now with the Key to flip through windows in the Switcher set it to control + grave accent instead.