consistent UIDs across multiple systems.

[silver.bullet at zoho.com]

Consider never to use a search engine and to e.g. search using a term
as e.g. "linux change user id" :p.

https://duckduckgo.com -> linux change user id ->

http://www.cyberciti.biz/faq/howto-change-rename-user-name-id/
https://stackoverflow.com/questions/18248056/change-user-id-in-linux
etc.

FWIW the first user on Linux usually gets the ID 1000 and on FreeBSD
usually 1001.

Be careful with changing ownership of directories and files using the
find command. I don't remember why it's tricky, but once I changed
ownership on a FreeBSD install from 1001 to 1000 and IIRC the FreeBSD
mailing list community and I failed to notice an issue when using find.

Regards,
Ralf