Actually the easiest way to handle what you want is to give yourself sudo privileges. I believe on Mac OS X your user (i.e., user1) would just need to be part of the admin group.
Once user1 is part of the admin group, then you can run any command from the terminal in the following way and it will use root privileges:
sudo mv /home/user1/files /home/user2/pictures
the very first time you ever do this, the system will give you a warning about 'with great power comes great responsibility...' and it will prompt you for a password. If you are running this command as user1, the password it wants is user1's password - not root's password nor user2's password.
Note that, by configuration, the system may cache the password for a set amount of time or until you end the terminal session. when it expires and you run sudo
as user1 it will prompt you again for user1's password.
sudo
only works for the specific command you give it.
Why not accept answer? Jonnie's solution worked ? – tgkprog – 2014-11-14T18:43:26.497