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moby--moby/docs/reference/commandline/cp.md
Ian Campbell fca6cda4b0 Clarify cp documentation behaviour with trailing "/."
Issue #30082 demonstrated that their is possible confusion with the "/."
where the tailing "." can appear to be merely punctuation within the
document rather than a highly pertinent part of `SRC_PATH`.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>
2017-01-13 13:58:25 +00:00

112 lines
5.2 KiB
Markdown

---
title: "cp"
description: "The cp command description and usage"
keywords: "copy, container, files, folders"
---
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# cp
```markdown
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 `/.` (that is: _slash_ followed by _dot_)
- the source directory is copied into this directory
- `SRC_PATH` does end with `/.` (that is: _slash_ followed by _dot_)
- 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](run.md#mount-tmpfs-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`.