Redirect the output of a command to a file when using sudo

Rather than > or », use tee.

Redirecting the output of commands run with sudo requires a different approach. For instance consider sudo ls > /root/somefile will not work since it is the shell that tries to write to that file. You can use ls | sudo tee -a /root/somefile to append, or ls | sudo tee /root/somefile to overwrite contents.

From https://help.ubuntu.com/community/RootSudo