File copy: Add new files, but do not replace files, to a set of folders I often need the following function:
I wish to make a copy operation  (usually from my phone to the cloud). I wish to copy a set of folders and subfolders with contents/files.

I wish all NEW files to be copied but NO FILES SHOULD BE REPLACED in the target.

One reson for doing this is that earlier backups in the cloud are incomplete. Copying to the cloud can consume a lot of time and bandwidth, I therefore wish to skip overwriting files that are already in the cloud. I wish to only copy NEW files that not yet reside in the cloud.

It would be like pressing "overwrite" for every duplicate folder but "skip" for every duplicate file, in a copy dialogue.

I have tried the app ES File Explorer. It handles all clouds relevant to me (Dropbox, Drive, Mega, OneDrive) in an efficient way. But I can not find the function described above. Files and folders are treated in the same way regarding overwrite/skip.

An example could be:

I make a backup of 1000 files to the cloud. The connection breaks after 900 files. I am not sure which 100 files still have to be copied.

I just want to restart the 1000 file backup and only the missing 100 files should be copied. This should work no matter in which folders/subfolders the missing files are located.

It is very simple to do manually. (Dilbert's boss could do it.  ;) ) Just press "overwrite" for duplicate folders and "skip" for duplicate files. But I can't sit and do that for hours. There ought to be a file manager that does it for me?
The app FolderSync solves the problem. You can choose whether to overwrite target files or not. (Even if you choose not to overwrite individual files, you can still include new files in subfolders into your backup, if you want.)

You can also choose whether to only backup/sync modified files (date or MD5 options). Under this option, a file deleted in the cloud, will not be uploaded again, unless modified.

The app has many options e.g.


synch both directions or just f.ex to (or from) the cloud
include/exclude subfolders
include/exclude filenames containing user defined strings
synch deletions is optional (files deleted on the phone will then also be deleted in the cloud)
and many more


It is able to handle thousands of files and also works under a less than optimal Internet connection. It connects to a multitude of clouds. It does scheduling and works discretely in the background.

So far it has solved my copy needs for the cloud.

...

Another good app is ES File Explorer. It is a file manager (not a sync program). It also handles the common clouds (I think you need "Pro" version for cloud Mega.)

ES File Explorer works well. But if you choose "do not overwrite files" you can not include subfolders. (Files and folders are treated in the same way with respect to overwrite/skip.) At least I couldn't make it work. For me it also had problems communicating with Microsoft cloud OneDrive for large backups. Maybe because my Internet connection is somewhat poor. "ES" functions well with other clouds over my Internet connection,  though.