  We formulate correlation functions for a one-dimensional interacting spinless
fermion model at finite temperature. By combination of a lattice path integral
formulation for thermodynamics with the algebraic Bethe ansatz for fermion
systems, the equal-time one-particle Green's function at arbitrary particle
density is expressed as a multiple integral form. Our formula reproduces
previously known results in the following three limits: the zero-temperature,
the infinite-temperature and the free fermion limits.
