@eltonfc It is interesting, I have never really thought of it. Swedish native speaker, and the infinite and imperative forms are (mostly) identical also in Swedish, so I haven't made the distinction.
But thinking of it, it's imperative, as I am commanding the machine to do something for me: "Open the (expletive) file".
As a software translator, I haven't thought of it either, but the imperative form comes naturally (and I follow the lead from other software as far as possible).
The biggest hurdle translating is when there are adjectives, as these are inflected by gender, so a menu item like "New" can have several forms in Swedish, and is often translated as "Create", which cannot.