How to pass password automatically for rsync SSH command?

Question

I need to do rsync by ssh and want to do it automatically without the need of passing password for ssh manually.

Answer 1

Another interesting possibility:

1. generate RSA, or DSA key pair (as it was described)
2. put public key to host (as it was already described)
3. run:

rsync --partial --progress --rsh="ssh -i dsa_private_file" host_name@host:/home/me/d .

Note: -i dsa_private_file which is your RSA/DSA private key

Basically, this approach is very similar to the one described by @Mad Scientist, however you do not have to copy your private key to ~/.ssh. In other words, it is useful for ad-hoc tasks (one time passwordless access)