-o password_stdin do not seem to be working on all systems, for instance freeBSD. etc.
You can also use
expect Interpreter, it should work with sshfs
and should do the trick.
Another solution would be
sshpass, for instance, let say your are backing up directory /var/www
mkdir /backup/$name && tar -czvf /backup/$name/"$name.tar.gz" /var/www
uploading backup file to backup server
sshpass -p "your_password" scp -r backup_user@target_ip:/home/ /backup/$name
So it will upload directory with today's backup
But still, as it was said higher, best(safe and simple) way would be to use ssh key pair
The only inconvenience would be that you have to go through the key generation process once on every server you need to pair, but it is better than keeping a password in plain text format on all servers you want to back up :),
Generating a Key Pair the Proper way
On Local server
ssh-keygen -t rsa
On remote Server
ssh root@remote_servers_ip "mkdir -p .ssh"
Uploading Generated Public Keys to the Remote Server
cat ~/.ssh/id_rsa.pub | ssh root@remote_servers_ip "cat >> ~/.ssh/authorized_keys"
Set Permissions on Remote server
ssh root@remote_servers_ip "chmod 700 ~/.ssh; chmod 640 ~/.ssh/authorized_keys"
Enabling SSH Protocol v2
uncomment "Protocol 2" in /etc/ssh/sshd_config
enabling public key authorization in sshd
uncomment "PubkeyAuthentication yes" in /etc/ssh/sshd_config
If StrictModes is set to yes in /etc/ssh/sshd_config then
restorecon -Rv ~/.ssh