-A 指定所有数据库

-B 指定单库，你这明显语法错误！再看看吧

mysqldump -uroot -P 3387 --skip-tz-utc --triggers --default-character-set=utf8mb4 --single-transaction --master-data=2 --set-gtid-purged=off --max-allowed-packet=512M -R -E -A >/var/lib/mysql/dump13387/FULL_P3387_jikt2_1013.sql
mysqldump -uroot -P 3397 --skip-tz-utc --triggers --default-character-set=utf8mb4 --single-transaction --master-data=2 --set-gtid-purged=off --max-allowed-packet=512M -R -E -B db_fc > /var/lib/mysql/data/FULL_P3397_0526.sql

https://mp.weixin.qq.com/s/CoZjiuaZAB1oFNkQUmm81g