Found existing config file ./my.cnf on the system.
Because this file might be in use, it was not replaced,
but was used in bootstrap (unless you used --defaults-file)
and when you later start the server.
The new default config file was created as ./my-new.cnf
以上提示是在执行了
scripts/mysql_install_db --user=mysql
之后提示的。这是由于我的/usr/local/mysql/下已经有了my.cnf。将其改名，再重试，就ok了