Note that sudo does not completely mimic root behaviour. Commands using
>, and presumably other composite commands, will depend on the user's
own permissions.
In an 'all-root' directory, with no existing file2:
sudo cp file1 file2 works as expected
sudo touch file2 works as expected
sudo cat file1 works as expected
sudo cat file1> file2 fails due to lack of write permission
su -c "cat file1> file2", then<password>, works as expected
It isn't just cat, I first noticed this some years ago with aggregate,
which also uses>. I assume that when the shell reaches the>, which is
effectively another command, the temporary sudo one-command permission
has expired. The trick with the quotation marks doesn't work, sudo
expects the entire quoted string to be the name of an executable.