For a uniform long charged line with l1 c/m the electric field intensity E is given as E = ρL/(π ε0.r).
Gauss’s static that divergence of D = ρu.
Gauss’s law states that total electric flux through any surface is equal to the total charge enclosed by surface.
An electric flux line is an imaginary path or a line drawn in such a way, that its direction at any point is the direction of electric field at that point.