Debian – Docker – debian:stretch-slim – install man and view manpages

debiandockerman

When using the debian:stretch Docker image, the /usr/share/man/ directory already contains many manpages, and man can be easily installed to view them:

$ apt-get update
$ apt-get install man
$ man ls
$ man cp

However, when using the debian:stretch-slim Docker image, the /usr/share/man/ directory is intentionally empty:

These tags are an experiment in providing a slimmer base (removing some extra files that are normally not necessary within containers, such as man pages and documentation)

How do I populate the /usr/share/man/ directory, so I can use man to view manpages for core utilities (such as cat, chmod, chown, cp, ls, mkdir, mv, rm, tail, etc) ?

Best Answer

The coreutils package populates the /usr/share/man/man1/ directory with manpages for core utilities.

However, simply running apt-get update and apt-get install coreutils is not sufficient, because dpkg has been configured to exclude /usr/share/man/*, using path-exclude in /etc/dpkg/dpkg.cfg.d/docker (see here and here).

So the first step is to remove that line from the /etc/dpkg/dpkg.cfg.d/docker file. One way to do this is by using sed:

$ sed -i '/path-exclude \/usr\/share\/man/d' /etc/dpkg/dpkg.cfg.d/docker

dpkg has also been configured to exclude /usr/share/groff/*, and this needs to be undone too (since groff is required in order to render manpages):

$ sed -i '/path-exclude \/usr\/share\/groff/d' /etc/dpkg/dpkg.cfg.d/docker

Now the /usr/share/man/man1/ directory needs to be populated from the coreutils package. Since coreutils is already installed in the debian:stretch-slim Docker image, it needs to be reinstalled:

$ apt-get update
$ apt-get install --reinstall coreutils

Finally, man can be installed and manpages can be viewed:

$ apt-get install man
$ man ls
$ man cp

It's also helpful to install less, which man will use for paginating the manpages, and provides a better experience than the default more paginator:

$ apt-get install less

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