  We investigate self-similar scalar field solutions to the Einstein equations
in whole cylinder symmetry. Imposing self-similarity on the spacetime gives
rise to a set of single variable functions describing the metric. Furthermore,
it is shown that the scalar field is dependent on a single unknown function of
the same variable and that the scalar field potential has exponential form. The
Einstein equations then take the form of a set of ODEs. Self-similarity also
gives rise to a singularity at the scaling origin. We discuss the number of
degrees of freedom at an arbitrary point and prove existence and uniqueness of
a 2-parameter family of solutions with a regular axis. We discuss the evolution
of these solutions away from the axis toward the past null cone of the
singularity, determining the maximal interval of existence in each case.
