Transferring Files Between host and container
Docker provides convenient ways to copy files between host and container. Open another Docker Quickstart Terminal. If your host is GNU/Linux, just open another terminal.
To copy file from container to host, issue the following command in the host terminal:
docker cp CONTAINER:SRC_PATH HOST_PATH
where
CONTAINERis the name of the containerSRC_PATHis the path of the file in container to copyHOST_PATHis the path of the host to copy to
For example, the following command will copy a file in the container to a Windows path:
docker cp ics-vm:/home/ics/a.txt /d/temp
Note that you can not specify the path in Windows as D:\temp, since : in docker cp command has special meaning.
To copy file from host to container, issue the following command in the host terminal:
docker cp HOST_SRC_PATH CONTAINER:DEST_PATH
where
HOST_SRC_PATHis the path of the host file to copyCONTAINERis the name of the containerDEST_PATHis the path in the container to copy to
For example, the following command will copy a folder in Windows into the container:
docker cp /d/myfolder ics-vm:/home/ics
- New a text file with casual contents in the host.
- Copy the text file to the container.
- Modify the content of the text file in the container.
- Copy the modified file back to the host.
Check whether the content of the modified file you get after the last step is expected. If it is the case, you are done!
However, you may encounter error when you are trying to save the modification in vim in step 3 above:
E45: 'readonly' option is set (add ! to override)
According to the message, the file is read-only, but you may use ! to force saving. Type
:w!
But you receive another error message this time (assuming the file name is a.txt):
"a.txt" E212: Can't open file for writing
It seems that you do not have the permission to write to this file. Type
:q!
to exit vim without saving. Back to shell, type
ls -l
to display detail information of the files. You will see a list like
total 4
-rw-r--r-- 1 root root 13 Sep 1 2016 a.txt
Here are some explanations of what the first column (for example, -rw-r--r--) of the list means. For more information about what each column means, please search the Internet.
You can see that the a.txt file is owned by root, and you do not have permission to modify it. This is because files copy into container will be owned by root. To change the owner of the copied files, issue the following command in the container:
sudo chown -R username a.txt
where username is your username in the container. This time you should modify the file successfully. So, remember to change the owner of files after copying them into the container.