Move folder contents into parent folder - Linux Commandline

I have a folderA that contains folderB that contains a lot of files. I would like to get rid of folderB, but not its contents. I want those contents to be inside of folderA. How can I accomplish this on the commandline?

$ cd /path/to/folderA
$ mv folderB/* .
$ rmdir folderB

Quick answer:

cd /path/to/folderA
find folderB -maxdepth 1 -mindepth 1 -exec mv {} . \;
rmdir folderB

Code-hardy answer:

cd /path/to/folderA
folderB_temp="$(mktemp -d -t folderB.XXXXXX)"
mv folderB "$folderB_temp"
find "$folderB_temp/folderB" -maxdepth 1 -mindepth 1 -exec mv {} . \;
rmdir --parents --ignore-fail-on-non-empty "$folderB_temp/folderB"