Move files from subfolder to current folder
Solution 1:
shorter version:
mv folder2/* .
Solution 2:
mv /folder1/folder2/* /folder1/
Solution 3:
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.