Ubuntu 18.04 Bionic `man` always returns "No manual entry for X"

[mallorydxw]

Here's what happens with the 17.10 image (correct behaviour):

% docker pull ubuntu:17.10
17.10: Pulling from library/ubuntu
Digest: sha256:91680dba9ee085d9d4d33e907842dbecb8891e3cc9f81175ba991d2d27bd862f
Status: Image is up to date for ubuntu:17.10
% docker run -ti --rm ubuntu:17.10 sh -c 'apt-get update && apt-get install -y man-db && man man | head'
Get:1 http://archive.ubuntu.com/ubuntu artful InRelease [237 kB]
Get:2 http://security.ubuntu.com/ubuntu artful-security InRelease [78.6 kB]
Get:3 http://security.ubuntu.com/ubuntu artful-security/universe Sources [17.3 kB]
Get:4 http://archive.ubuntu.com/ubuntu artful-updates InRelease [81.7 kB]
Get:5 http://security.ubuntu.com/ubuntu artful-security/main amd64 Packages [188 kB]
Get:6 http://archive.ubuntu.com/ubuntu artful-backports InRelease [72.2 kB]
Get:7 http://archive.ubuntu.com/ubuntu artful/universe Sources [11.1 MB]
Get:8 http://security.ubuntu.com/ubuntu artful-security/restricted amd64 Packages [2931 B]
Get:9 http://security.ubuntu.com/ubuntu artful-security/universe amd64 Packages [72.3 kB]
Get:10 http://security.ubuntu.com/ubuntu artful-security/multiverse amd64 Packages [1826 B]
Get:11 http://archive.ubuntu.com/ubuntu artful/multiverse amd64 Packages [185 kB]
Get:12 http://archive.ubuntu.com/ubuntu artful/main amd64 Packages [1416 kB]
Get:13 http://archive.ubuntu.com/ubuntu artful/universe amd64 Packages [10.8 MB]
Get:14 http://archive.ubuntu.com/ubuntu artful/restricted amd64 Packages [14.7 kB]
Get:15 http://archive.ubuntu.com/ubuntu artful-updates/universe Sources [37.7 kB]
Get:16 http://archive.ubuntu.com/ubuntu artful-updates/universe amd64 Packages [131 kB]
Get:17 http://archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages [306 kB]
Get:18 http://archive.ubuntu.com/ubuntu artful-updates/multiverse amd64 Packages [4384 B]
Get:19 http://archive.ubuntu.com/ubuntu artful-updates/restricted amd64 Packages [2931 B]
Get:20 http://archive.ubuntu.com/ubuntu artful-backports/main amd64 Packages [1469 B]
Get:21 http://archive.ubuntu.com/ubuntu artful-backports/universe amd64 Packages [4130 B]
Fetched 24.7 MB in 4s (5434 kB/s)
Reading package lists... Done
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  bsdmainutils groff-base libbsd0 libgdbm3 libpipeline1
Suggested packages:
  cpp wamerican | wordlist whois vacation groff less www-browser
The following NEW packages will be installed:
  bsdmainutils groff-base libbsd0 libgdbm3 libpipeline1 man-db
0 upgraded, 6 newly installed, 0 to remove and 2 not upgraded.
Need to get 2301 kB of archives.
After this operation, 6484 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu artful/main amd64 groff-base amd64 1.22.3-9 [1144 kB]
Get:2 http://archive.ubuntu.com/ubuntu artful/main amd64 libbsd0 amd64 0.8.6-1 [41.6 kB]
Get:3 http://archive.ubuntu.com/ubuntu artful/main amd64 bsdmainutils amd64 9.0.12+nmu1ubuntu1 [179 kB]
Get:4 http://archive.ubuntu.com/ubuntu artful/main amd64 libgdbm3 amd64 1.8.3-14 [16.8 kB]
Get:5 http://archive.ubuntu.com/ubuntu artful/main amd64 libpipeline1 amd64 1.4.2-1 [25.2 kB]
Get:6 http://archive.ubuntu.com/ubuntu artful/main amd64 man-db amd64 2.7.6.1-2 [895 kB]
Fetched 2301 kB in 1s (1858 kB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package groff-base.
(Reading database ... 4111 files and directories currently installed.)
Preparing to unpack .../0-groff-base_1.22.3-9_amd64.deb ...
Unpacking groff-base (1.22.3-9) ...
Selecting previously unselected package libbsd0:amd64.
Preparing to unpack .../1-libbsd0_0.8.6-1_amd64.deb ...
Unpacking libbsd0:amd64 (0.8.6-1) ...
Selecting previously unselected package bsdmainutils.
Preparing to unpack .../2-bsdmainutils_9.0.12+nmu1ubuntu1_amd64.deb ...
Unpacking bsdmainutils (9.0.12+nmu1ubuntu1) ...
Selecting previously unselected package libgdbm3:amd64.
Preparing to unpack .../3-libgdbm3_1.8.3-14_amd64.deb ...
Unpacking libgdbm3:amd64 (1.8.3-14) ...
Selecting previously unselected package libpipeline1:amd64.
Preparing to unpack .../4-libpipeline1_1.4.2-1_amd64.deb ...
Unpacking libpipeline1:amd64 (1.4.2-1) ...
Selecting previously unselected package man-db.
Preparing to unpack .../5-man-db_2.7.6.1-2_amd64.deb ...
Unpacking man-db (2.7.6.1-2) ...
Setting up libgdbm3:amd64 (1.8.3-14) ...
Setting up groff-base (1.22.3-9) ...
Setting up libpipeline1:amd64 (1.4.2-1) ...
Setting up libbsd0:amd64 (0.8.6-1) ...
Processing triggers for libc-bin (2.26-0ubuntu2.1) ...
Setting up bsdmainutils (9.0.12+nmu1ubuntu1) ...
update-alternatives: using /usr/bin/bsd-write to provide /usr/bin/write (write) in auto mode
update-alternatives: using /usr/bin/bsd-from to provide /usr/bin/from (from) in auto mode
Setting up man-db (2.7.6.1-2) ...
debconf: unable to initialize frontend: Dialog
debconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76.)
debconf: falling back to frontend: Readline
debconf: unable to initialize frontend: Readline
debconf: (Can't locate Term/ReadLine.pm in @INC (you may need to install the Term::ReadLine module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.26.0 /usr/local/share/perl/5.26.0 /usr/lib/x86_64-linux-gnu/perl5/5.26 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.26 /usr/share/perl/5.26 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base) at /usr/share/perl5/Debconf/FrontEnd/Readline.pm line 7.)
debconf: falling back to frontend: Teletype
Building database of manual pages ...
MAN(1)                                         Manual pager utils                                         MAN(1)

NAME
       man - an interface to the on-line reference manuals

SYNOPSIS
       man [-C file] [-d] [-D] [--warnings[=warnings]] [-R encoding] [-L locale] [-m system[,...]] [-M path] [-S
       list] [-e extension] [-i|-I] [--regex|--wildcard] [--names-only] [-a] [-u] [--no-subpages] [-P pager] [-r
       prompt]  [-7]  [-E  encoding]  [--no-hyphenation]  [--no-justification]  [-p  string]  [-t]  [-T[device]]
       [-H[browser]] [-X[dpi]] [-Z] [[section] page[.section] ...] ...

And here's what happens with the 18.04 image:

% docker pull ubuntu:18.04
18.04: Pulling from library/ubuntu
Digest: sha256:4decfd6e336e1cf246127151753d2a24a3185b5f667b91b925e8b38e7ea903a0
Status: Image is up to date for ubuntu:18.04
% docker run -ti --rm ubuntu:18.04 sh -c 'apt-get update && apt-get install -y man-db && man man | head'
Get:1 http://security.ubuntu.com/ubuntu bionic-security InRelease [65.4 kB]
Get:2 http://archive.ubuntu.com/ubuntu bionic InRelease [235 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [65.4 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [65.5 kB]
Get:5 http://archive.ubuntu.com/ubuntu bionic/universe Sources [11.5 MB]
Get:6 http://archive.ubuntu.com/ubuntu bionic/restricted amd64 Packages [13.3 kB]
Get:7 http://archive.ubuntu.com/ubuntu bionic/multiverse amd64 Packages [185 kB]
Get:8 http://archive.ubuntu.com/ubuntu bionic/universe amd64 Packages [11.3 MB]
Get:9 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages [1346 kB]
Fetched 24.8 MB in 5s (5102 kB/s)
Reading package lists... Done
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  bsdmainutils groff-base libbsd0 libgdbm5 libpipeline1
Suggested packages:
  cpp wamerican | wordlist whois vacation groff gdbm-l10n apparmor less www-browser
The following NEW packages will be installed:
  bsdmainutils groff-base libbsd0 libgdbm5 libpipeline1 man-db
0 upgraded, 6 newly installed, 0 to remove and 44 not upgraded.
Need to get 2446 kB of archives.
After this operation, 6788 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu bionic/main amd64 libbsd0 amd64 0.8.7-1 [41.5 kB]
Get:2 http://archive.ubuntu.com/ubuntu bionic/main amd64 bsdmainutils amd64 11.1.2ubuntu1 [181 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic/main amd64 groff-base amd64 1.22.3-10 [1153 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic/main amd64 libgdbm5 amd64 1.14.1-6 [26.0 kB]
Get:5 http://archive.ubuntu.com/ubuntu bionic/main amd64 libpipeline1 amd64 1.5.0-1 [25.3 kB]
Get:6 http://archive.ubuntu.com/ubuntu bionic/main amd64 man-db amd64 2.8.3-2 [1019 kB]
Fetched 2446 kB in 1s (1647 kB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package libbsd0:amd64.
(Reading database ... 4333 files and directories currently installed.)
Preparing to unpack .../0-libbsd0_0.8.7-1_amd64.deb ...
Unpacking libbsd0:amd64 (0.8.7-1) ...
Selecting previously unselected package bsdmainutils.
Preparing to unpack .../1-bsdmainutils_11.1.2ubuntu1_amd64.deb ...
Unpacking bsdmainutils (11.1.2ubuntu1) ...
Selecting previously unselected package groff-base.
Preparing to unpack .../2-groff-base_1.22.3-10_amd64.deb ...
Unpacking groff-base (1.22.3-10) ...
Selecting previously unselected package libgdbm5:amd64.
Preparing to unpack .../3-libgdbm5_1.14.1-6_amd64.deb ...
Unpacking libgdbm5:amd64 (1.14.1-6) ...
Selecting previously unselected package libpipeline1:amd64.
Preparing to unpack .../4-libpipeline1_1.5.0-1_amd64.deb ...
Unpacking libpipeline1:amd64 (1.5.0-1) ...
Selecting previously unselected package man-db.
Preparing to unpack .../5-man-db_2.8.3-2_amd64.deb ...
Unpacking man-db (2.8.3-2) ...
Setting up groff-base (1.22.3-10) ...
Setting up libpipeline1:amd64 (1.5.0-1) ...
Setting up libgdbm5:amd64 (1.14.1-6) ...
Setting up libbsd0:amd64 (0.8.7-1) ...
Processing triggers for libc-bin (2.26-0ubuntu2.1) ...
Setting up bsdmainutils (11.1.2ubuntu1) ...
update-alternatives: using /usr/bin/bsd-write to provide /usr/bin/write (write) in auto mode
update-alternatives: warning: skip creation of /usr/share/man/man1/write.1.gz because associated file /usr/share/man/man1/bsd-write.1.gz (of link group write) doesn't exist
update-alternatives: using /usr/bin/bsd-from to provide /usr/bin/from (from) in auto mode
update-alternatives: warning: skip creation of /usr/share/man/man1/from.1.gz because associated file /usr/share/man/man1/bsd-from.1.gz (of link group from) doesn't exist
Setting up man-db (2.8.3-2) ...
debconf: unable to initialize frontend: Dialog
debconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76.)
debconf: falling back to frontend: Readline
debconf: unable to initialize frontend: Readline
debconf: (Can't locate Term/ReadLine.pm in @INC (you may need to install the Term::ReadLine module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.26.1 /usr/local/share/perl/5.26.1 /usr/lib/x86_64-linux-gnu/perl5/5.26 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.26 /usr/share/perl/5.26 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base) at /usr/share/perl5/Debconf/FrontEnd/Readline.pm line 7.)
debconf: falling back to frontend: Teletype
Building database of manual pages ...
No manual entry for man
See 'man 7 undocumented' for help when manual pages are not available.

I ran the Ubuntu 18.04 beta 2 installer in a VM and man man works there. I also checked which man-related packages were installed (in case some package names had been changed between releases). It only has man-db and manpages (adding manpages to the above command does not fix the problem).

[tianon]

I think this was an intentional change in the Bionic tarballs generated by Canonical in order to reduce their size:

$ docker run --rm ubuntu:bionic cat /etc/dpkg/dpkg.cfg.d/excludes
# Drop all man pages
path-exclude=/usr/share/man/*

# Drop all documentation ...
path-exclude=/usr/share/doc/*

# ... except copyright files ...
path-include=/usr/share/doc/*/copyright

# ... and Debian changelogs
path-include=/usr/share/doc/*/changelog.Debian.*

(Given services like http://manpages.ubuntu.com/ and https://manpages.debian.org/, it shouldn't often be necessary to have man pages inside a container.)

[mallorydxw]

Thank you!

it shouldn't often be necessary to have man pages inside a container.

My development environment is a tmux session inside a Docker container, so I'm in one of the rare situations where man pages are desirable.

In case anybody else runs into this problem, the solution is to just add these lines to the top of your Dockerfile:

# Do not exclude man pages & other documentation
RUN rm /etc/dpkg/dpkg.cfg.d/excludes
# Reinstall all currently installed packages in order to get the man pages back
RUN apt-get update && \
    dpkg -l | grep ^ii | cut -d' ' -f3 | xargs apt-get install -y --reinstall && \
    rm -r /var/lib/apt/lists/*

[EvanKrall]

I just ran into this issue in another situation where man pages inside containers are desirable: we use containers to perform integration tests on a package that we build: build the package, install it inside a container, make sure that our executables start up and that the man pages are there.

I know it's maybe not your decision, and I should probably be appealing to Canonical instead, but this situation seems pretty broken to me. I understand the desire to have the base image be very light, but whether my downstream images should be able to contain manpages should be left up to me. I'd prefer the excludes file be removed by default. It's not at all obvious that the excludes file is the cause of this behavior, as it causes no extra (googleable) output for apt/dpkg.

[jasonmp85]

(Given services like http://manpages.ubuntu.com/ and https://manpages.debian.org/, it shouldn't often be necessary to have man pages inside a container.)

Thanks for deciding that for us. I built a dev container to help me do some Linux dev on a macOS laptop on a flight. Surprise! No man pages!

[jasonmp85]

(Also this is really hard to Google for and I came to read the Dockerfile as a last resort; I figured I had screwed something up somehow. Even manually installing man and reinstalling packages without --no-install-recommends didn't fix it and I wasn't sure what was wrong. I looked in /etc/apt for something causing it but didn't realize dpkg was the binary responsible).

[mwhudson]

So I'm testing a change that makes things work like this:

root@5ba21de0c7de:/# man ls
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.
root@5ba21de0c7de:/# unminimize 
This system has been minimized by removing packages and content that are
not required on a system that users do not log into.

This script restores the content and packages that are found on a default
Ubuntu server system.

Reinstallation of packages may fail due to changes to the system
configuration, the presence of third-party packages, or for other
reasons.
Would you like to continue? [y/N]y
[lots of output snipped]
root@5ba21de0c7de:/# man ls
[usual output]

Does this seem like an improvement to everyone?

[dirkcgrunwald]

One problem I see with this (just trying) is that "unminimize" is difficult to run in a dockerfile build. I did an "echo y | unminimize", but there's an internal upgrade that then fails due to not getting confirmation on upgrade.

Using "apt-get update && apt-get upgrade -y && (echo y | DEBIAN_FRONTEND=noninteractive sh -x /usr/local/sbin/unminimize)" appears to work.

In my case, the resulting image is 2.4GB larger after this process, which I'm assuming is due to layers in Dockerfiles. I will probably need to go back and rebuild the base ( https://github.com/jupyter/docker-stacks/tree/master/datascience-notebook )

[AGhost-7]

Is there a plan to support ubuntu server images as well (not just core)? I am trying to develop from a container and I am running into this issue.

[mallorydxw]

You can avoid running upgrade -y immediately before running unminimize if you use yes instead of echo y.

Here's a minimal solution for Cosmic:

FROM ubuntu:18.10

RUN yes | unminimize && \
    apt-get install -y man-db && \
    rm -r /var/lib/apt/lists/*

[tianon]

@mwhudson is yes | unminimize still the "best" solution here, or is there something better? (perhaps a command-line --yes flag on unminimize?)

[mwhudson]

yes | unminimize is till the best thing I think. There are some improvements in this area in cosmic which could/should be backported to bionic but I don't think they affect that.