Merging two folders in python.

Recently I wanted to merge two folders in python and overwrite existing files in the destination folders. Shutil library offers a lot of high level file handling functions, however, noone of them offers offer the merging. In particular the function shutil.copytree() copy recursively the source three in the destination tree, but it requires that the destination folder must not exist.

In order to merge folders, here there is a small function that does exactly that:

#recursively merge two folders including subfolders
def mergefolders(root_src_dir, root_dst_dir):
    for src_dir, dirs, files in os.walk(root_src_dir):
        dst_dir = src_dir.replace(root_src_dir, root_dst_dir, 1)
        if not os.path.exists(dst_dir):
            os.makedirs(dst_dir)
        for file_ in files:
            src_file = os.path.join(src_dir, file_)
            dst_file = os.path.join(dst_dir, file_)
            if os.path.exists(dst_file):
                os.remove(dst_file)
            shutil.copy(src_file, dst_dir)