Batch Mode with Basic Authentication using the Ubuntu SFTP command line client

SFTP (SSSH Transfer Protocol, or, Secure File Transfer Protocol) is an extension of the SSH (Secure Shell Protocol) protocol for file management. SFTP supports multiple authentication mechanisms including basic authentication (user & password). SFTP allows executing multiple consecutive commands by supplying an SFTP batch file like.

cd /the/directory
ls

Unfortunately, the SFTP command line client that comes with Ubuntu doesn’t allow us to use basic authentication in combination with batch files in a straight forward manner. The fix is shown below.

export SSHPASS="verysecret"  
  
sshpass -e sftp -P 22 -o BatchMode=no -o PubkeyAuthentication=no -b - user@sftp.example.com <<EOF  
cd /the/directory
ls
exit  
EOF

This is, admittedly, a bit hacky. We are disabling batch mode while supplying a batch file. But it seems to work nonetheless.

Key points:

• sshpass is used to add non-interactive user & password authentication
• the user is specified in the url user@sftp.example.com
• the -e flag to sshpass tells it to read the password from the environment variable SSHPASS
• we tell sftp to disable batch mode (BatchMode=no) and to not check host keys (PubkeyAuthentication=no, we could of course also add the host key to known_hosts for improved security)
• the batch file is supplied from standard in via -b - and using a Heredoc after the sftp command