Weapon focus Pathfinder

[Andry]

In pathfinder does weapon focus's attack bonus also apply to combat maneuvers (like trip) with said weapon?

[Geddy2112]

Absolutely does

"When you attempt to perform a combat maneuver, make an attack roll and add your CMB in place of your normal attack bonus. Add any bonuses you currently have on attack rolls due to spells, feats, and other effects. These bonuses must be applicable to the weapon or attack used to perform the maneuver."

[D.M.Hentchel]

Yes, performing a combat manuever is still an attack roll so feats that provide bonuses on attack rolls also apply to CMB. So long as the bonus is applicable.

It is worth noting that many combat manuevers do not invovle a weapon (such as bullrush or overrrun) and weapon focus would never be applicable.