Problem with mysqldump: "--defaults-extra-file" option is not working as expected

I found the answer: --defaults-extra-file must be the first option. This works as expected:

...\right_path\mysqldump --defaults-extra-file=d:\1.cnf
                         --add-drop-database --databases my_database_name

Also meet this problem. Found there's another situation that would cause --defaults-extra-file option not recognized.

When you changed IFS in script, it's possible to hit this problem. The solution is to reset IFS before execute mysql statement.

For reference.