Copy a File Out With docker cp

docker cp copies files between a container and your computer. It works in both directions and it works on stopped containers, which makes it the easiest way to rescue a file from a container that is about to be deleted.

The syntax is the same as cp, except that a path inside a container starts with the container name and a colon: container:/path.

Start a container with a file in it

docker run -d --name cp-demo alpine:3.24 sleep 300

Unable to find image
Status: Downloaded newer image for alpine:3.24

docker exec cp-demo sh -c "echo report line one > /tmp/report.txt"

Copy a file out

The first argument is the source and the second is the destination. A dot means the current folder.

docker cp cp-demo:/tmp/report.txt .
Get-Content .\report.txt

report line one

In a terminal that is not interactive, docker cp prints nothing when it works. That is why the second command is there, and why it is the proof. You can also give the destination a new name, for example docker cp cp-demo:/tmp/report.txt .\copy-of-report.txt.

Copy a file in

Set-Content -Path local.txt -Value "from the host"
docker cp .\local.txt cp-demo:/tmp/local.txt
docker exec cp-demo cat /tmp/local.txt

from the host

A file copied in is owned by root inside the container, whatever its owner was on your computer.

Copy a whole folder

Give a folder as the source and you get the folder with everything in it.

docker cp cp-demo:/etc/apk .\apk-copy
Get-ChildItem .\apk-copy | Select-Object -ExpandProperty Name | Sort-Object

keys
repositories

If the destination folder already exists, Docker copies the source folder into it. Use a name that does not exist yet when you want a clean copy.

Error: the file is not there

docker cp cp-demo:/tmp/nope.txt .

Error response from daemon: Could not find the file /tmp/nope.txt in container cp-demo

The path is wrong, or the file was never created. List the folder first with docker exec cp-demo ls /tmp. The path is checked inside the container, so use forward slashes, even on Windows.

It works on a stopped container

docker stop --timeout 1 cp-demo
docker cp cp-demo:/tmp/local.txt .\rescued.txt
Get-Content .\rescued.txt

cp-demo
from the host

This is the rescue case. The container stopped, and the file is still there until you remove the container. Copy what you need before you run docker rm.

docker rm cp-demo

Related course: Docker for Beginners.