give interactive mode tips when interactive

src/Operations.jl

@@ -1321,14 +1321,14 @@ function assert_can_add(ctx::Context, pkgs::Vector{PackageSpec})
         existing_uuid == pkg.uuid ||
             pkgerror("""Refusing to add package $(err_rep(pkg)).
                      Package `$(pkg.name)=$(existing_uuid)` with the same name already exists as a direct dependency.
-                     To remove the existing package, use `import Pkg; Pkg.rm("$(pkg.name)")`.
+                     To remove the existing package, use `$(Base.isinteractive() ? """pkg> rm $(pkg.name)""" : """import Pkg; Pkg.rm("$(pkg.name)")""")`.
                      """)
         # package with the same uuid exist in the project: assert they have the same name
         name = findfirst(==(pkg.uuid), ctx.env.project.deps)
         name === nothing || name == pkg.name ||
             pkgerror("""Refusing to add package $(err_rep(pkg)).
                      Package `$name=$(pkg.uuid)` with the same UUID already exists as a direct dependency.
-                     To remove the existing package, use `import Pkg; Pkg.rm("$name")`.
+                     To remove the existing package, use `$(Base.isinteractive() ? """pkg> rm $name""" : """import Pkg; Pkg.rm("$name")""")`.
                      """)
         # package with the same uuid exist in the manifest: assert they have the same name
         entry = get(ctx.env.manifest, pkg.uuid, nothing)

src/Registry/Registry.jl

@@ -156,10 +156,11 @@ function check_registry_state(reg)
     reg_currently_uses_pkg_server = reg.tree_info !== nothing
     reg_should_use_pkg_server = registry_use_pkg_server()
     if reg_currently_uses_pkg_server && !reg_should_use_pkg_server
+        pkg_cmd = Base.isinteractive() ? "pkg> rm $(reg.name); add $(reg.name)" : "using Pkg; Pkg.Registry.rm(\"$(reg.name)\"); Pkg.Registry.add(\"$(reg.name)\")"
         msg = string(
             "Your registry may be outdated. We recommend that you run the ",
             "following command: ",
-            "using Pkg; Pkg.Registry.rm(\"$(reg.name)\"); Pkg.Registry.add(\"$(reg.name)\")",
+            pkg_cmd,
         )
         @warn(msg)
     end