I’ve installed a package from a domU and tried to transfer to dom0 but failed, what I’ve done in dom0:
sudo cat /usr/bin/(application-name) \
| qvm-run --pass-io [dom]U 'cat > /usr/bin/(application-name)'
And it shows:/bin/bash: line 1: /usr/bin(application-name): Permission denied
I guess you mean copy application from dom0 to domU; if that is the case, qvm-copy-to-vm [dom]U /usr/bin/(application-name) is OK.
Sorry, but I do want to copy application from domU to dom0, not dom0 to domU, and the command is actually followed the documentation mentioned by @fsflover.
(Apologize for my bad grammar)
Try something like this:
tar cf - /path/to/files | qvm-run --pass-io [dom]U 'cd $HOME/Downloads; tar xfv - ’
This will copy the files or directories from dom0:/path/to/files/* to domU $HOME/Downloads/path/to/files.
Explanation: This command spools the tar output stream on dom0 to the stdin stream on domU, and the tar command on domU extracts stdin stream and places the extracted files/directory into the current directory ./Downloads
Be careful not to overwrite any system files unless you actually know what you are doing! It’s safer to move those files to the actual dir by hand after some verification.
Please try to respect other’s time and will to help. If you clicked on that link and read the page, you would find the answer on that link.
My bad, It does copy with another commad, sorry to bother you guys. 
Great @whoareyou you made it. If some of the posts resolved it for you. please consider to mark it as a solution so it could help other users too.