Migrate Linux from X to Y.

First of all, login with root , then using usermod to change username:

usermod -l newUserName -d /home/newUserName -m oldUserName

Linux use uid to identify user, so changing username will not affect permissions.

Then, find all broken symlinks and fix it:

find . -xtype l

Last but not least, Search all configurations and change username, I recommand ripgrep.

rg oldUserName

• https://askubuntu.com/questions/34074/how-do-i-change-my-username