As I am preparing for a Linux exam, I need to practice various commands on a separate Docker image and refer to manuals while using it.
By default, Docker images are minimal, and the Ubuntu image does not include man pages.
For instance, when you try to access a manual page, you encounter the following message:
root@54354b49f7a9:/# man man
This system has been minimized by removing packages and content that are
not required on a system that users do not log into.
To restore this content, including manpages, you can run the 'unminimize'
command. You will still need to ensure the 'man-db' package is installed.
To address this, you can use the unminimize command in the Dockerfile to restore the missing components. Here’s how:
FROM ubuntu:22.04
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update -y
RUN apt install man -y
RUN yes | /usr/local/sbin/unminimize
CMD ["bash"]
After creating this Dockerfile, build and run the image with the following commands:
docker build . -f Dockerfile -t ubuntu
docker run --rm -it ubuntu bash
And it works! Now you can access man pages within the Docker container.
root@dd8f78de34d0:/# man sed
SED(1) User Commands SED(1)
NAME
sed - stream editor for filtering and transforming text