How do I use my keyfile to sftp transfer data from one server to another

Try:

sftp -o "IdentityFile=keyname" [email protected]

You can use -o to pass any option that's valid in ~/.ssh/config.

Copy your PUBLIC key to the server using traditional means.

On server:

• Create .ssh if it doesn't exist:

[[ ! -d "${HOME}/.ssh" ]] && mkdir -p "${HOME}/.ssh"

• Implement the public key:

cat /path/to/public_key.pub >> "${HOME}/.ssh/authorized_keys"

• Set appropriate permissions. OpenSSH is VERY ANAL about the permissions of the files in question:

chmod go-rwx "${HOME}" "${HOME}/.ssh/authorized_keys"

After that, you should be able to log in from the client using the PRIVATE key. To automate a transfer, you want to use a batch file, which is just a text file containing a list of commands to execute.

echo "put filename.foo /safe/path/filename.foo" >> /tmp/batchfile.txt
sftp -b /tmp/batchfile.txt -oIdentityFile=/path/to/private_key user@host

Alternatively, feel free to create a ~/.ssh/config file in ssh_config format so you can just type this in the future:

sftp -b /tmp/batchfile.txt host

Sample contents of ~/.ssh/config

Host the_hostname
    User user_name
    IdentityFile /path/to/private_key