Want to know how to copy files between host and container using docker?
There are various ways to copy files. Docker cp is a command that lets you copy files between the host and containers.
In this tutorial, you will learn how to use docker cp to copy files and folders between a container and a host.
Copy files using docker cp command
First, let's know the syntax to use the docker cp command.
Syntax -
Docker cp accepts the source and the destination where the files should be copied.
# Syntax to Copy from Container to Docker Host
docker cp {options} CONTAINER:SOURCE DESTINATION
# Syntax to Copy from Docker Host to Container
docker cp {options} SOURCE CONTAINER:DESTINATION
Parameters -
- Container: Source - This is the source path of the container
- Destination - This is the destination path of the host
docker cp demo.txt my-container:/demo.txt
In the above example, demo.txt is being copied from your working directory to /demo.txt in the my-container container. You can reverse this process too.
You will need to replace the my-container with a container id or name along with a colon(:). You can use the docker ps command to find the name or id of the container.
You can't directly copy files from one container to another. When using the docker cp command, you will need a local filesystem path and a container path. If you want to know which type of questions are asked in the interview then you must check out the top frequently asked docker interview questions and answers.
Copy Folder/Directories using docker cp command -
A directory path ends with a /. If the destination directory doesn't exist then a new directory will be created which will contain the contents of the source directory. If the specified source path doesn't exist then it will raise an error.
docker cp /home/demo/website apache-container:/var/www/html/.
In the above example, docker will copy the entire directory /home/demo/website into the destined directory /var/www/html/
Limitations of docker cp command
Docker cp is not a complete implementation of the cp shell command, there are only two fags are supported: -a and -L :
- -a: This is an archival mode that preserves user and group details on copied files.
- -L: It follows symlinks in the source directory to copy the contents of link targets.
Conclusion
The docker cp command is a simple and useful tool for copying files and directories between a host and a container in Docker. By understanding its syntax and parameters, you can easily transfer files and directories back and forth.
However, it's important to note that there are limitations to this command and it does not support all the features of the cp shell command. Nonetheless, it remains a powerful and convenient way to manage files and directories in a Docker environment.
FAQ
1. How do I copy from one container to another container?
You can use the docker cp to copy from one container to another. You will need to copy files from a container to the local filesystem and then you can copy those files into the targeted container.
2. What should I do if I encounter permission errors while copying files with the docker cp command?
If you encounter permission errors while copying files with the docker cp command, you can try running the command with elevated privileges using the sudo command or you can try changing the ownership or permissions of the files or directories.
3. Can I use the docker cp command to copy entire directories?
Yes, You can use the docker cp command to copy entire directories between a container and the host. Simply replace the file path with the directory path in the command.
4. How do I verify that files have been successfully copied using the docker cp command?
To verify that files have been successfully copied using the docker cp command, you can use the ls command inside the container to list the contents of the destination directory.
