DockerCLI/docs/reference/commandline/cp.md

cp

Usage:  docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|-
        docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH

Copy files/folders between a container and the local filesystem

Use '-' as the source to read a tar archive from stdin
and extract it to a directory destination in a container.
Use '-' as the destination to stream a tar archive of a
container source to stdout.

Options:
  -L, --follow-link   Always follow symbol link in SRC_PATH
      --help          Print usage

The docker cp utility copies the contents of SRC_PATH to the DEST_PATH. You can copy from the container's file system to the local machine or the reverse, from the local filesystem to the container. If - is specified for either the SRC_PATH or DEST_PATH, you can also stream a tar archive from STDIN or to STDOUT. The CONTAINER can be a running or stopped container. The SRC_PATH or DEST_PATH can be a file or directory.

The docker cp command assumes container paths are relative to the container's / (root) directory. This means supplying the initial forward slash is optional; The command sees compassionate_darwin:/tmp/foo/myfile.txt and compassionate_darwin:tmp/foo/myfile.txt as identical. Local machine paths can be an absolute or relative value. The command interprets a local machine's relative paths as relative to the current working directory where docker cp is run.

The cp command behaves like the Unix cp -a command in that directories are copied recursively with permissions preserved if possible. Ownership is set to the user and primary group at the destination. For example, files copied to a container are created with UID:GID of the root user. Files copied to the local machine are created with the UID:GID of the user which invoked the docker cp command. If you specify the -L option, docker cp follows any symbolic link in the SRC_PATH. docker cp does not create parent directories for DEST_PATH if they do not exist.

Assuming a path separator of /, a first argument of SRC_PATH and second argument of DEST_PATH, the behavior is as follows:

• SRC_PATH specifies a file
  • DEST_PATH does not exist
    • the file is saved to a file created at DEST_PATH
  • DEST_PATH does not exist and ends with /
    • Error condition: the destination directory must exist.
  • DEST_PATH exists and is a file
    • the destination is overwritten with the source file's contents
  • DEST_PATH exists and is a directory
    • the file is copied into this directory using the basename from SRC_PATH
• SRC_PATH specifies a directory
  • DEST_PATH does not exist
    • DEST_PATH is created as a directory and the contents of the source directory are copied into this directory
  • DEST_PATH exists and is a file
    • Error condition: cannot copy a directory to a file
  • DEST_PATH exists and is a directory
    • SRC_PATH does not end with /.
      • the source directory is copied into this directory
    • SRC_PATH does end with /.
      • the content of the source directory is copied into this directory

The command requires SRC_PATH and DEST_PATH to exist according to the above rules. If SRC_PATH is local and is a symbolic link, the symbolic link, not the target, is copied by default. To copy the link target and not the link, specify the -L option.

A colon (:) is used as a delimiter between CONTAINER and its path. You can also use : when specifying paths to a SRC_PATH or DEST_PATH on a local machine, for example file:name.txt. If you use a : in a local machine path, you must be explicit with a relative or absolute path, for example:

`/path/to/file:name.txt` or `./file:name.txt`

It is not possible to copy certain system files such as resources under /proc, /sys, /dev, tmpfs, and mounts created by the user in the container. However, you can still copy such files by manually running tar in docker exec. For example (consider SRC_PATH and DEST_PATH are directories):

$ docker exec foo tar Ccf $(dirname SRC_PATH) - $(basename SRC_PATH) | tar Cxf DEST_PATH -

or

$ tar Ccf $(dirname SRC_PATH) - $(basename SRC_PATH) | docker exec -i foo tar Cxf DEST_PATH -

Using - as the SRC_PATH streams the contents of STDIN as a tar archive. The command extracts the content of the tar to the DEST_PATH in container's filesystem. In this case, DEST_PATH must specify a directory. Using - as the DEST_PATH streams the contents of the resource as a tar archive to STDOUT.