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.
shorter version:
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 andshopt -u dotglob
to switch back to default.recursively move files to current folder:
be aware that you won't be overwriting existing files.