Can't install SharedArrays

I am most likely missing something obvious here, but using Julia 0.6.0 on Fedora 26, I cannot install SharedArrays.

julia> using SharedArrays
ERROR: ArgumentError: Module SharedArrays not found in current path.

julia> Pkg.add("SharedArrays")
ERROR: unknown package SharedArrays

What am I missing?

There’s no such package on 0.6. you are likely being confused by 0.7 doc where this is a built-in module