How do I edit a file after I shell to a Docker container?
DockerCommand Line-InterfaceEditorEditDocker Problem Overview
I successfully shelled to a Docker container using:
docker exec -i -t 69f1711a205e bash
Now I need to edit file and I don't have any editors inside:
root@69f1711a205e:/# nano
bash: nano: command not found
root@69f1711a205e:/# pico
bash: pico: command not found
root@69f1711a205e:/# vi
bash: vi: command not found
root@69f1711a205e:/# vim
bash: vim: command not found
root@69f1711a205e:/# emacs
bash: emacs: command not found
root@69f1711a205e:/#
How do I edit files?
Docker Solutions
Solution 1 - Docker
As in the comments, there's no default editor set - strange - the $EDITOR
environment variable is empty. You can log in into a container with:
docker exec -it <container> bash
And run:
apt-get update
apt-get install vim
Or use the following Dockerfile:
FROM confluent/postgres-bw:0.1
RUN ["apt-get", "update"]
RUN ["apt-get", "install", "-y", "vim"]
Docker images are delivered trimmed to the bare minimum - so no editor is installed with the shipped container. That's why there's a need to install it manually.
EDIT
I also encourage you to read my post about the topic.
Solution 2 - Docker
If you don't want to add an editor just to make a few small changes (e.g., change the Tomcat configuration), you can just use:
docker cp <container>:/path/to/file.ext .
which copies it to your local machine (to your current directory). Then edit the file locally using your favorite editor, and then do a
docker cp file.ext <container>:/path/to/file.ext
to replace the old file.
Solution 3 - Docker
You can use cat
if it's installed, which will most likely be the case if it's not a bare/raw container. It works in a pinch, and ok when copy+pasting to a proper editor locally.
cat > file
# 1. type in your content
# 2. leave a newline at end of file
# 3. ctrl-c / (better: ctrl-d)
cat file
cat
will output each line on receiving a newline. Make sure to add a newline for that last line. ctrl-c sends a SIGINT
for cat to exit gracefully. From the comments you see that you can also hit ctrl-d to denote end-of-file ("no more input coming").
Another option is something like infilter
which injects a process into the container namespace with some ptrace magic: https://github.com/yadutaf/infilter
Solution 4 - Docker
To keep your Docker images small, don't install unnecessary editors. You can edit the files over SSH from the Docker host to the container:
vim scp://remoteuser@containerip//path/to/document
Solution 5 - Docker
For common edit operations I prefer to install vi
(vim-tiny), which uses only 1491 kB or nano
which uses 1707 kB.
In other hand vim
uses 28.9 MB.
We have to remember that in order for apt-get install
to work, we have to do the update
the first time, so:
apt-get update
apt-get install vim-tiny
To start the editor in CLI we need to enter vi
.
Solution 6 - Docker
You can open existing file with
cat filename.extension
and copy all the existing text on clipboard.
Then delete old file with
rm filename.extension
or rename old file with
mv old-filename.extension new-filename.extension
Create new file with
cat > new-file.extension
Then paste all text copied on clipboard, press Enter
and exit with save by pressing ctrl+z
. And voila no need to install any kind of editors.
Solution 7 - Docker
You can use cat
if installed, with the >
caracter.
Here is the manipulation :
cat > file_to_edit
#1 Write or Paste you text
#2 don't forget to leave a blank line at the end of file
#3 Ctrl + C to apply configuration
Now you can see the result with the command
cat file
Solution 8 - Docker
Sometime you must first run the container with root
:
docker exec -ti --user root <container-id> /bin/bash
Then in the container, to install Vim or something else:
apt-get install vim
Solution 9 - Docker
I use "docker run" (not "docker exec"), and I'm in a restricted zone where we cannot install an editor. But I have an editor on the Docker host.
My workaround is: Bind mount a volume from the Docker host to the container (https://docs.docker.com/engine/reference/run/#/volume-shared-filesystems), and edit the file outside the container. It looks like this:
docker run -v /outside/dir:/container/dir
This is mostly for experimenting, and later I'd change the file when building the image.
Solution 10 - Docker
After you shelled to the Docker container, just type:
apt-get update
apt-get install nano
Solution 11 - Docker
You can just edit your file on host and quickly copy it into and run it inside the container. Here is my one-line shortcut to copy and run a Python file:
docker cp main.py my-container:/data/scripts/ ; docker exec -it my-container python /data/scripts/main.py
Solution 12 - Docker
If you use Windows container and you want change any file, you can get and use Vim in Powershell console easily.
To shelled to the Windows Docker container with PowerShell:
docker exec -it <name> powershell
-
First install Chocolatey package manager
Invoke-WebRequest https://chocolatey.org/install.ps1 -UseBasicParsing | Invoke-Expression;
-
Install Vim
choco install vim
-
Refresh ENVIRONMENTAL VARIABLE You can just
exit
and shell back to the container -
Go to file location and Vim it
vim file.txt
Solution 13 - Docker
It is kind of screwy, but in a pinch you can use sed
or awk
to make small edits or remove text. Be careful with your regex targets of course and be aware that you're likely root
on your container and might have to re-adjust permissions.
For example, removing a full line that contains text matching a regex:
awk '!/targetText/' file.txt > temp && mv temp file.txt
Solution 14 - Docker
See Stack Overflow question https://stackoverflow.com/questions/12696125/sed-edit-file-in-place
It would be a good option here, if:
-
To modify a large file, it's impossible to use
cat
. -
Install Vim is not allowed or takes too long. My situation is using the MySQL 5.7 image when I want to change the
my.cnf
file, there is novim
,vi
, and Vim install takes too long (China Great Firewall).sed
is provided in the image, and it's quite simple. My usage is likesed -i /s/testtobechanged/textwanted/g filename
Use man sed
or look for other tutorials for more complex usage.
Solution 15 - Docker
If you can only shell into container with bin/sh (in case bin/bash doesn't work) and apt or apt-get doesn't work in the container, check whether apk is installed by entering apk in command prompt inside the container. If yes, you can install nano as follows: apk add nano
then nano will work as usual
Solution 16 - Docker
An easy way to edit a few lines would be:
echo "deb http://deb.debian.org/debian stretch main" > sources.list
Solution 17 - Docker
You can also use a special container which will contain only the command you need: Vim. I chose python-vim. It assumes that the data you want to edit are in a data container built with the following Dockerfile:
FROM debian:jessie
ENV MY_USER_PASS my_user_pass
RUN groupadd --gid 1001 my_user
RUN useradd -ms /bin/bash --home /home/my_user \
-p $(echo "print crypt("${MY_USER_PASS:-password}", "salt")" | perl) \
--uid 1001 --gid 1001 my_user
ADD src /home/my_user/src
RUN chown -R my_user:my_user /home/my_user/src
RUN chmod u+x /home/my_user/src
CMD ["true"]
You will be able to edit your data by mounting a Docker volume (src_volume) which will be shared by your data container (src_data) and the python-vim container.
docker volume create --name src_volume
docker build -t src_data .
docker run -d -v src_volume:/home/my_user/src --name src_data_1 src_data
docker run --rm -it -v src_volume:/src fedeg/python-vim:latest
That way, you do not change your containers. You just use a special container for this work.
Solution 18 - Docker
I agree that @hkong's answer should be accepted, as it avoids adding additional packages to the container. However, I found that after pasting the modified file to the container, some of them tended to have restricted access so that docker daemon failed to start. In this case, assign the modified file with some permission then pasting to the container.
Solution 19 - Docker
docker comes up with no editors. so simply install vim, 36MB space don't kill your docker!
Solution 20 - Docker
Make sure to update the container before trying to install the editor.
apt-get update
apt-get install nano vi
Solution 21 - Docker
First login as root :
docker run -u root -ti