moby--moby/docs/reference/commandline/cp.md

cp

Copy files/folders between a container and the local filesystem.

Usage:  docker cp [options] CONTAINER:PATH LOCALPATH|-
        docker cp [options] LOCALPATH|- CONTAINER:PATH

--help  Print usage statement

In the first synopsis form, the docker cp utility copies the contents of PATH from the filesystem of CONTAINER to the LOCALPATH (or stream as a tar archive to STDOUT if - is specified).

In the second synopsis form, the contents of LOCALPATH (or a tar archive streamed from STDIN if - is specified) are copied from the local machine to PATH in the filesystem of CONTAINER.

You can copy to or from either a running or stopped container. The PATH can be a file or directory. The docker cp command assumes all CONTAINER:PATH values are relative to the / (root) directory of the container. 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. If a LOCALPATH value is not absolute, is it considered relative to the current working directory.

Behavior is similar to the common Unix utility cp -a in that directories are copied recursively with permissions preserved if possible. Ownership is set to the user and primary group on the receiving end of the transfer. For example, files copied to a container will be created with UID:GID of the root user. Files copied to the local machine will be created with the UID:GID of the user which invoked the docker cp command.

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

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

The command requires SRC_PATH and DST_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.

A colon (:) is used as a delimiter between CONTAINER and PATH, but : could also be in a valid LOCALPATH, like file:name.txt. This ambiguity is resolved by requiring a LOCALPATH with a : to be made 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, and mounts created by the user in the container.

Using - as the first argument in place of a LOCALPATH will stream the contents of STDIN as a tar archive which will be extracted to the PATH in the filesystem of the destination container. In this case, PATH must specify a directory.

Using - as the second argument in place of a LOCALPATH will stream the contents of the resource from the source container as a tar archive to STDOUT.