docker/man/docker-cp.1.md

% DOCKER(1) Docker User Manuals % Docker Community % JUNE 2014

NAME

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

SYNOPSIS

docker cp [--help] CONTAINER:PATH LOCALPATH|- LOCALPATH|- CONTAINER:PATH

DESCRIPTION

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_PATH 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.

OPTIONS

--help Print usage statement

EXAMPLES

Suppose a container has finished producing some output as a file it saves to somewhere in its filesystem. This could be the output of a build job or some other computation. You can copy these outputs from the container to a location on your local host.

If you want to copy the /tmp/foo directory from a container to the existing /tmp directory on your host. If you run docker cp in your ~ (home) directory on the local host:

	$ docker cp compassionate_darwin:tmp/foo /tmp

Docker creates a /tmp/foo directory on your host. Alternatively, you can omit the leading slash in the command. If you execute this command from your home directory:

	$ docker cp compassionate_darwin:tmp/foo tmp

If ~/tmp does not exist, Docker will create it and copy the contents of /tmp/foo from the container into this new directory. If ~/tmp already exists as a directory, then Docker will copy the contents of /tmp/foo from the container into a directory at ~/tmp/foo.

When copying a single file to an existing LOCALPATH, the docker cp command will either overwrite the contents of LOCALPATH if it is a file or place it into LOCALPATH if it is a directory, overwriting an existing file of the same name if one exists. For example, this command:

	$ docker cp sharp_ptolemy:/tmp/foo/myfile.txt /test

If /test does not exist on the local machine, it will be created as a file with the contents of /tmp/foo/myfile.txt from the container. If /test exists as a file, it will be overwritten. Lastly, if /tmp exists as a directory, the file will be copied to /test/myfile.txt.

Next, suppose you want to copy a file or folder into a container. For example, this could be a configuration file or some other input to a long running computation that you would like to place into a created container before it starts. This is useful because it does not require the configuration file or other input to exist in the container image.

If you have a file, config.yml, in the current directory on your local host and wish to copy it to an existing directory at /etc/my-app.d in a container, this command can be used:

	$ docker cp config.yml myappcontainer:/etc/my-app.d

If you have several files in a local directory /config which you need to copy to a directory /etc/my-app.d in a container:

	$ docker cp /config/. myappcontainer:/etc/my-app.d

The above command will copy the contents of the local /config directory into the directory /etc/my-app.d in the container.

HISTORY

April 2014, Originally compiled by William Henry (whenry at redhat dot com) based on docker.com source material and internal work. June 2014, updated by Sven Dowideit SvenDowideit@home.org.au May 2015, updated by Josh Hawn josh.hawn@docker.com