Does this do the job for you?
julia> getvars() = [string(v) for v in sort!(names(Main)) if isdefined(Main, v) && !(v in (:Base, :Main, :Core, :InteractiveUtils, :ans))]
getvars (generic function with 1 method)
julia> getvars()
1-element Array{String,1}:
"getvars"
julia> x =5
5
julia> getvars()
2-element Array{String,1}:
"getvars"
"x"
julia> y = 10
10
julia> getvars()
3-element Array{String,1}:
"getvars"
"x"
"y"