Move files from subfolder to current folder

shorter version:

mv folder2/* .

mv /folder1/folder2/* /folder1/

there is a caveat to be aware of if you have invisible files (starting with '.') in your folder. dotglob (*) won't expand (and mv won't move) invisible files unless you change it's behaviour with shopt. shopt -s dotglob to expand invisible files and shopt -u dotglob to switch back to default.