SCP (Secure Copy Protocol)
SSH can be used not only for remote login but also for file transfer in a secure way. There are two protocols for transferring files with SSH – SCP (Secure Copy Protocol) and SFTP (Secure File Transfer Protocol). In this section, we'll explain SCP.
Transferring from local to remote
To transfer a file from the local computer to the remote server, the following five sets of information are needed for the SCP command.
Key file
- Private key file path on your local computer (usually, under the .ssh directory)
Source file
- Source file path on your local computer
Destination
- User name of the remote server
- IP address of the remote server
- Destination directory path on the remote server. If you want to transfer the file to the user's home directory of the remote server, you can skip this argument.
For a better understanding, please go through the following practice section.
Practice 1
Objective:
Transfer a file from the local computer to the remote server
The following are the paths of the file to be transferred and the destination directory.
- File to be transferred: ~/dir_ch7_local/sample.txt (on the local computer)
- Destination directory: ~/dir_ch7_remote (on the remote server)
Note: For this practice, open two terminals (command lines). One for a local operation and another one for a remote operation.
1. Create a directory on the remote server
Create a directory for receiving a file.
For this operation, use the terminal connected to the remote server.
cd ~
mkdir dir_ch7_remote
2. Create a sample file on the local computer
Create a sample file for transferring to the remote server.
For this operation, use the local terminal that is not connected to the remote server.
cd ~
mkdir dir_ch7_local
cd dir_ch7_local
touch sample.txt
3. Transfer the file
Run the scp command with the private key path, source file path, and destination directory path.
scp -i ~/.ssh/id_rsa sample.txt ubuntu@18.143.143.190:dir_ch7_remote
sample.txt 100% 0 0.0KB/s 00:00
If you set a passphrase for the private key, you need to enter the passphrase to move forward.
4. Check if the file is transferred properly.
Using the terminal connected to the remote server, check if the file is successfully transferred.
ls dir_ch7_remote
You can see that the file is successfully transferred.
sample.txt
Tips: Transfer a directory
When you want to transfer a directory with files underneath, use the -r option. The following is the example command.
Command Line - INPUT
scp -i ~/.ssh/id_rsa -r sample_dir ubuntu@18.143.143.190:dir_ch7_remote
Transferring from remote to local
To transfer a file from the remote server to the local computer, the following five sets of information are needed for the SCP command.
Key file
- Private key file path on your local computer (usually under the .ssh directory)
Source file
- User name of the remote server
- IP address of the remote server
- Source file path on the remote server
Destination
- Destination directory path on your local computer. If you want to transfer the file to your home directory on your computer, you can skip this argument.
For a better understanding, please go through the following practice section.
Practice 2
Objective:
Transfer a directory from the remote server to the local computer
The following are the paths of the directory to be transferred and the destination directory.
- Directory to be transferred: ~/dir_ch7_remote (on the remote server)
- Destination directory: ~/dir_ch7_local (on the local computer)
Note: This practice can be done only with the local terminal.
1. Transfer the directory
Run the scp command with the private key path, source directory path, and destination directory path.
cd ~
scp -i ~/.ssh/id_rsa -r ubuntu@18.143.143.190:dir_ch7_remote dir_ch7_local
sample.txt 100% 0 0.0KB/s 00:00
If you set a passphrase for the private key, you need to enter the passphrase to move forward.
2. Check if the directory is transferred properly.
Check if the directory is successfully transferred from the remote server to the local computer.
ls dir_ch7_local
You can see that the file is successfully transferred.
dir_ch7_remote sample.txt
Typical Mistakes
There are two typical mistakes you might make when you run the scp command.
1. Forgetting to add : (colon)
When you forget to add : (colon), the command will have a different meaning. The command will create a file copy on your local computer. For example, if you run the following command (without a colon at the end), you'll create a file named ubuntu@18.143.143.190 in the same directory.
scp -i ~/.ssh/id_rsa sample.txt ubuntu@18.143.143.190
ubuntu@18.143.143.190
2. Misusing spacing
Omitting or adding an extra space is also a common mistake. Check spaces when you encounter an error message in your command line.
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