US αβ keyboard layout

Provides greek letters as level 3 (right Alt switch):

key <AC01> {        [  a,   A,  Greek_alpha,    Greek_ALPHA                 ]       }; // α Α
key <AB05> {        [  b,   B,  Greek_beta,     Greek_BETA                  ]       }; // β Β
key <AB03> {        [  c,   C,  Greek_psi,      Greek_PSI                   ]       }; // ψ Ψ
key <AC03> {        [  d,   D,  Greek_delta,    Greek_DELTA                 ]       }; // δ Δ
key <AD03> {        [  e,   E,  Greek_epsilon,  Greek_EPSILON               ]       }; // ε Ε
key <AC04> {        [  f,   F,  Greek_phi,      Greek_PHI                   ]       }; // φ Φ
key <AC05> {        [  g,   G,  Greek_gamma,    Greek_GAMMA                 ]       }; // γ Γ
key <AC06> {        [  h,   H,  Greek_eta,      Greek_ETA                   ]       }; // η Η
key <AD08> {        [  i,   I,  Greek_iota,     Greek_IOTA                  ]       }; // ι Ι
key <AC07> {        [  j,   J,  Greek_xi,       Greek_XI                    ]       }; // ξ Ξ
key <AC08> {        [  k,   K,  Greek_kappa,    Greek_KAPPA                 ]       }; // κ Κ
key <AC09> {        [  l,   L,  Greek_lamda,    Greek_LAMDA                 ]       }; // λ Λ
key <AB07> {        [  m,   M,  Greek_mu,       Greek_MU                    ]       }; // μ Μ
key <AB06> {        [  n,   N,  Greek_nu,       Greek_NU                    ]       }; // ν Ν
key <AD09> {        [  o,   O,  Greek_omicron,  Greek_OMICRON               ]       }; // ο Ο
key <AD10> {        [  p,   P,  Greek_pi,       Greek_PI                    ]       }; // π Π
key <AD04> {        [  r,   R,  Greek_rho,      Greek_RHO                   ]       }; // ρ Ρ
key <AC02> {        [  s,   S,  Greek_sigma,    Greek_SIGMA                 ]       }; // σ Σ
key <AD05> {        [  t,   T,  Greek_tau,      Greek_TAU                   ]       }; // τ Τ
key <AD07> {        [  u,   U,  Greek_theta,    Greek_THETA                 ]       }; // θ Θ
key <AB04> {        [  v,   V,  Greek_omega,    Greek_OMEGA                 ]       }; // ω Ω
key <AB02> {        [  x,   X,  Greek_chi,      Greek_CHI                   ]       }; // χ Χ
key <AD06> {        [  y,   Y,  Greek_upsilon,  Greek_UPSILON               ]       }; // υ Υ
key <AB01> {        [  z,   Z,  Greek_zeta,     Greek_ZETA                  ]       }; // ζ Ζ
key <AB09> {        [  period,  greater,  periodcentered,     periodcentered]       }; // · ·

Installation

This is probably a wrong way to install layout variants, but xkb is too arcane to for me to figure out. So:

1. Copy us file to /usr/share/X11/xkb/symbols/, this will overwrite the existing file.
2. Add this entry near the English (US) variants in /usr/share/X11/xkb/rules/evdev.xml

      <variant>
         <configItem>
           <name>alphabeta</name>
           <shortDescription>US αβ</shortDescription>
           <description>English (US αβ)</description>
         </configItem>
       </variant>
   

3. Maybe restart or logout & login
4. Go to keyboard settings and add "English (US αβ)" layout. On Ubuntu you need to click on "English (United States)" first, which then expands into variants.