sftp in unix shell script without password

Automate File Transfers: SFTP in Unix Shell Script Without Password

By John ThomasFebruary 12, 2026

Streamlining tasks in Unix can be both empowering and time-saving, especially when it comes to automating repetitive operations like transferring files securely. One such automation involves utilizing SFTP (SSH File Transfer Protocol) within Unix shell scripts. But navigating SFTP with passwords for automation can often pose challenges. So, let's delve into leveraging key-based authentication for SFTP in Unix shell scripts without passwords.

You might be wondering, why opt for passwordless SFTP? Besides enhancing security by eliminating the risk of exposed passwords, passwordless SFTP also eases the process of automating file transfers. It's a seamless and convenient approach that boosts operational efficiency.

Setting up Host For Passwordless SFTP

To set up host for passwordless SFTP, you'll need to generate SSH key pair on your local machine and add the public key to the list of authorized keys on the remote host. This establishes a secure trust relationship between your local machine and the remote host.

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The process involves these steps:

Generating SSH Key Pair Locally

You can generate a new SSH key pair using the SSH keygen utility. You could opt for an RSA key for this task.

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Adding Public Key to Authorized Keys File

Once you've generated the key pair, the public key needs to be added to the 'authorized_keys' file on the remote host. This can be done via the 'ssh-copy-id' utility, which securely copies your public key to the remote host.

Integrating Passwordless SFTP in Unix Shell Scripts

Now that the prerequisite is set, you can leverage the passwordless SFTP in your Unix shell scripts for automating file transfers. This can be achieved using the 'sftp' command within a shell script.

Here's a basic example:

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```bash #!/bin/bash sshpass -p your_password sftp user@remote_host::/path/to/remote /path/to/local ```

Note that the 'sshpass' command is used to provide the password where required. But with passwordless SFTP, you don't need this command and your script can look like this:

```bash #!/bin/bash sftp user@remote_host::/path/to/remote /path/to/local ```

Remember to replace 'user@remote_host' with your SSH username and remote host details, and '/path/to/remote' and '/path/to/local' with your source and destination directories.

Using SCP Instead of SFTP

Instead of SFTP, you might also consider using 'scp' (secure copy) command in your scripts. SCP is simpler to use and often more reliable for file transfers. Here's how you can do it:

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```bash #!/bin/bash scp user@remote_host:/path/to/remote/* /path/to/local ```

Though SCP transfers files in a non-secure way, it's still useful when speed is a concern and the files you're transferring are not sensitive data.

In essence, automating file transfers via SFTP or SCP in Unix shell scripts improves efficiency and reduces manual errors. And with passwordless SFTP, you can add an extra layer of security and simplicity to your automated workflows.

Investigating and implementing these methods opens the door to a realm of streamlined, secure, and efficient data management. So, get started with your SSH key pair, script your file transfers, and enjoy the advantage that automation provides.