Sitemap1.xml, sitemap2.xml, etc

[outdoors]

If I have over 50000 pages, do I need to create sitemap1.xml, sitemap2.xml prior to running the script or will the script create these for me?

[admin]

Sitemap generator script doesn't have write access to the domain root, so you should create those files manually (empty files, similar to single sitemap.xml) and set 0666 permissions for them.