A Guide to SCP: Secure File Transfer on Ubuntu

SCP command examples

The SCP command lets you securely copy files between computers. Its basic structure involves specifying options, the source file location, and the destination location, making SCP file transfer on Ubuntu straightforward.

The scp command syntax uses the following format:

scp [OPTION] [user@]SRC_HOST:]file1 [user@]DEST_HOST:]file2

• OPTION – scp options that specify cipher, SSH configuration, SSH port, limit, recursive copy, etc.
• [user@]SRC_HOST:]file1 – path to the source file.
• [user@]DEST_HOST:]:file2 – path to the destination file.

Local files can be specified using an absolute or relative path, while remote file names must include a user and host specification.

The most commonly used options for the SCP command are:

• -P – Specifies the remote host ssh port.
• -p – Preserves file modification and access times.
• -q – Use this option to suppress the progress meter and non-error messages.
• -C – This option forces scp to compress the data as it is sent to the destination machine.
• -r – This option tells scp you to copy directories recursively.

Transferring files

Moving a single file from your computer to another computer using SCP is common. You’ll use a specific command structure, telling SCP which file to send and where to put it on the remote machine.

scp [options] /path/to/local/file username@remote:/path/to/destination

For example, to transfer a file named `example.txt` from the local machine to a remote machine with the IP address `192.168.0.2`, use the following command:

scp example.txt username@192.168.0.2:/home/username/

To transfer a file from a remote machine to the local machine, use the following command:

scp [options] username@remote:/path/to/file /path/to/destination

For example, to transfer a file named `example.txt` from a remote machine with the IP address `192.168.0.2` to the local machine, use the following command:

scp username@192.168.0.2:/home/username/example.txt /home/localuser/

If you want to save the file under a different name, specify the new file name at the destination. If SSH on the remote host is listening on a port other than the default 22, then you can specify the port using the -P argument:

scp -P 2322 example.txt username@192.168.0.2:/home/username/newName.txt

Transferring directories

Copying an entire folder, along with all its contents, from your computer to another is also simple with SCP. You just need to add a small option to the command to tell SCP to copy the whole directory recursively.

scp [options] -r /path/to/local/directory username@remote:/path/to/destination

For example, to transfer a directory named `example` from the local machine to a remote machine with the IP address `192.168.0.2`, use the following command:

scp -r example/ username@192.168.0.2:/home/username/

To transfer a directory from a remote machine to the local machine, use the following command:

scp [options] -r username@remote:/path/to/directory /path/to/destination

For example, to transfer a directory named `example` from a remote machine with the IP address `192.168.0.2` to the local machine, use the following command:

scp -r username@192.168.0.2:/home/username/example/ /home/localuser/

That should do it!

Conclusion:

• Using the SSH protocol, SCP (secure copy) is an essential command-line utility for securely transferring files and directories between networked devices.
• It provides a secure way to transfer files over a network and is particularly useful for protecting sensitive information on insecure networks.
• Understanding the SCP command’s basic syntax and commonly used options is crucial for efficient usage.
• The examples demonstrate transferring files and directories between local and remote machines using SCP on Ubuntu Linux.