How to run a mysqldump from a .txt or .sql file inside a command line window?
The commandline mysql allows \! to do what you want, but you appear to be in Windows, which does not really allow for such a feature.

So, No, you can't do it.

For reading INSERT statements (etc) back in there is the source command.

Can you turn things inside out?  You can get a list of databases, or otherwise create MySQL commands, from 

mysql ... -e "statement..."


and you redirect that to a .bat file, which could then be executed.

It seems like you need a .bat file.