Why can I not transfer a db from one container to another?

Question

Why can I not transfer a db from one container to another?

In my case, I have 2 mariadb containers running with 2 seperate volumes:

CONTAINER ID   IMAGE                                 COMMAND                  CREATED          STATUS                    PORTS                                                                                                                                                 NAMES
952988c62c2c   mariadb:10.4                          "docker-entrypoint.s…"   22 minutes ago   Up 22 minutes             3306/tcp                                                                                                                                              php_dev_db_1
799f2226367f   mariadb:10.4                          "docker-entrypoint.s…"   4 days ago       Up 30 minutes (healthy)   0.0.0.0:3306->3306/tcp, :::3306->3306/tcp                                                                                                             test_magento-db-1

And I tried to transfer the database from one to another via a pipe:

docker exec 799f2226367f mysqldump -u magento -pmagento magento > docker exec 952988c62c2c mysql -u magento -pmagento magento

But I get the error:

mysqldump: Couldn't find table: "exec"

And I don’t know why.

Asked By: Dimitrios Desyllas

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Source

Answer 1

I try to transfer the database from one to another via a pipe

so you need to use a pipe (|) rather than a redirection (>):

docker exec 799f2226367f mysqldump -u magento -pmagento magento | docker exec 952988c62c2c mysql -u magento -pmagento magento

The error you got happens because a redirection only consumes the following word, so your command is equivalent to

docker exec 799f2226367f mysqldump -u magento -pmagento magento exec 952988c62c2c mysql -u magento -pmagento magento > docker

i.e. mysqldump tries to dump the magento, exec, 952988c62c2c, and mysql tables.

Answered By: Stephen Kitt