Uploading and Downloading Files over SSH on Linux
SSH is commonly used for remote shell access, but the same secure connection can also transfer files. The scp command provides a straightforward way to copy individual files or directories between a local machine and an SSH server.
1. Prerequisites
Before using scp, make sure:
- You can connect to the server with SSH.
- You know the remote username and hostname or IP address.
- The destination path is writable by that user.
- Your SSH key or other authentication method is configured.
2. Upload a File
The general form is:
scp local_file user@remote_host:/remote/directory/For example:
scp example.txt user@example.com:/home/user/This copies example.txt from the current machine to /home/user/ on the remote host.
3. Download a File
Reverse the source and destination:
scp user@example.com:/home/user/example.txt ./The final ./ means the file is saved in the current local directory.
4. Copy a Directory
Use -r for recursive directory copies.
Upload a directory:
scp -r local_directory/ user@example.com:/srv/data/Download a directory:
scp -r user@example.com:/srv/data/project/ ./project/For large directory trees or repeated synchronization, rsync over SSH is often more efficient because it can transfer only changed data and resume partial work more effectively.
5. Use a Custom SSH Port
scp uses uppercase -P for the remote port:
scp -P 2222 example.txt user@example.com:/home/user/If you frequently use the same host and port, configure them in ~/.ssh/config so both ssh and scp can reuse the settings.
6. Use a Specific SSH Key
scp -i ~/.ssh/id_ed25519 example.txt user@example.com:/home/user/Protect private keys with appropriate filesystem permissions and never commit them to a repository.
7. Modern Alternative: sftp
For interactive transfers, SSH also provides SFTP:
sftp user@example.comInside the SFTP prompt, commands such as put, get, ls, and cd are available.
Conclusion
scp is a convenient tool for secure one-off file transfers over SSH. Use -r for directories, -P for a custom port, and an SSH configuration file to keep repeated connections simple. For large or recurring synchronizations, consider rsync over SSH instead.
