When I replaced my original Ubuntu server with the (then) more current Ubuntu 18.04, I also moved MySQL databases and wanted to have them backed up regularly.
I had used the script AutoMySQLBackup which did the job fine, and installed it on the new machine. (When I first found the script, I adapted for PowerShell on Windows it to backup my SQL Server databases)
On the new machine, however, the tool mysqldump issued the warning
[Warning] Using a password on the command line interface can be insecure.
The change seems to have been introduced in MySQL 5.6, and the solution to the warning is documented in the MySQL 5.6 Reference Manual. There are also answers on SO regarding the warning
mysql_config_editor set --login-path=local --host=localhost --user=username --password mysql --login-path=local -e "statement"
I guess I tried to change the .sh script to call mysqldump with –login-path instead of –user/–password.
As the original script is not maintained anymore, I found this fork of AutoMySQLBackup which is still active, and also documents the use of –login-path.