In the GNOME Yelp docs, it says that Yelp supports viewing HTML. But when I run yelp file:///home/myusername/Desktop/test.html, it displays "The URL can't be shown."

How can I resolve it? Actually I want to view my docs offline which I've converted into HTML from markdown.

Using Ubuntu 20.04.

tl;dr

The summary of all the following is roughly this:

• Remove or move the directory /usr/share/help/C/gnome-help.
• Run the command sudo apt reinstall gnome-user-docs gnome-getting-started-docs ubuntu-docs.
• The missing directory and its contents must come back.

This works OK in one of my 20.04 system, but not on another 20.04 system. Both systems are up-to-date.

I want to find out what makes this difference.

After upgrading from 19.10 to 20.04 the GNOME Help application (yelp) cannot find GNOME help files. For example, when I am in the GNOME Files application (nautilus) and press F1 I get the following error message in the yelp window:

Document Not Found
The URI ‘help:gnome-help/files’ does not point to a valid page.

The same thing occurs in other GNOME applications, like gedit, gnome-calculator etc.

yelp can display the man pages OK. The problem is only with the "help" pages. Is there any package that needs to be installed?

I tried to install package gnome-user-guide, but it didn't help. Packages:

gnome-getting-started-docs
gnome-user-docs
ubuntu-docs
xorg-docs-core

are already installed and up-to-date.

It seems* that the files needed are the ones under /usr/share/help/C/gnome-help/ and the package gnome-user-docs is the one that provides these (https://packages.ubuntu.com/focal/all/gnome-user-docs/filelist). However, even removing, purging and re-installing this package does not bring these files to my system.

*Note: dpkg -S /usr/share/help/C/gnome-help/files.page output is this:

gnome-user-docs: /usr/share/help/C/gnome-help/files.page

Also ls -lisad /usr/share/help/ /usr/share/help/C output is:

8651957 4 drwxr-xr-x 59 root root 4096 May 14 19:55 /usr/share/help/
8651631 4 drwxr-xr-x 31 root root 4096 May 17 17:39 /usr/share/help/C

and permissions and ownership of the files within these directories is -rw-r--r-- root root.

Similarly, other GNOME packages (for example, gnome-calculator) when (re)installed, they do not populate the relevant directory under /usr/share/help/C/.

I tested by copying /usr/share/help/C/gnome-help/ directory and its contents from another system and then reinstalling the gnome-user-docs package. The re-installation deleted the necessary files which I just copied there! Before doing the re-installation, but after copying these files manually, yelp was able to display its home screen and the relevant help screens OK. After the re-installation, the above mentioned problem occurs.

I have tried with various locales with the installation of gnome-user-docs package. Every time the same thing occurs. The files that I copied manually under /usr/share/help/C/ are being deleted:

# LANG=en_US.UTF-8 apt --reinstall install gnome-user-docs
# LANG=en_GB.UTF-8 apt --reinstall install gnome-user-docs
# LANG=C.UTF-8     apt --reinstall install gnome-user-docs

My locale output is this:

LANG=C.UTF-8
LANGUAGE=
LC_CTYPE="C.UTF-8"
LC_NUMERIC=en_GB.UTF-8
LC_TIME=en_GB.UTF-8
LC_COLLATE="C.UTF-8"
LC_MONETARY=en_GB.UTF-8
LC_MESSAGES="C.UTF-8"
LC_PAPER=en_GB.UTF-8
LC_NAME=en_GB.UTF-8
LC_ADDRESS=en_GB.UTF-8
LC_TELEPHONE=en_GB.UTF-8
LC_MEASUREMENT=en_GB.UTF-8
LC_IDENTIFICATION=en_GB.UTF-8
LC_ALL=

(Note that I tested with LANG=en_US.UTF-8 also; result was the same.)

The output of check-language-support --show-installed is:

firefox-locale-en gimp-help-en hunspell-en-au hunspell-en-ca hunspell-en-gb hunspell-en-us hunspell-en-za hyphen-en-ca hyphen-en-gb hyphen-en-us language-pack-en language-pack-gnome-en libreoffice-help-en-gb libreoffice-help-en-us libreoffice-l10n-en-gb libreoffice-l10n-en-za mythes-en-au mythes-en-us poppler-data thunderbird-locale-en thunderbird-locale-en-gb thunderbird-locale-en-us wamerican wbritish

Currently installed packages:

# apt --installed list | grep -i "docs"

gnome-getting-started-docs/focal,focal,now 3.36.1-0ubuntu1 all [installed]
gnome-user-docs/focal,focal,now 3.36.1-0ubuntu1 all [installed]
ubuntu-docs/focal,focal,now 20.04.2 all [installed]
xorg-docs-core/focal,focal,now 1:1.7.1-1.1 all [installed,automatic]

More Information

(1)

The output of sudo apt-cache depends yelp is like this:

yelp
  Depends: libc6
  Depends: libglib2.0-0
  Depends: libgtk-3-0
  Depends: libwebkit2gtk-4.0-37
  Depends: libyelp0
 |Depends: dconf-gsettings-backend
  Depends: <gsettings-backend>
    dconf-gsettings-backend
  Depends: python3-distro
  Depends: yelp-xsl
  Depends: man-db
    man-db:i386
  Recommends: docbook-xml

Note: This is the same output as on another system which does not have this problem.

(2)

The checksums for the yelp package are OK:

$ debsums yelp | wc -l
230
$ debsums yelp | grep 'OK$' | wc -l
230
$ debsums -a yelp | grep 'OK$' | wc -l
230

However, the checksums for the gnome-user-docs package show inconsistent results. On the system with this problem:

$ debsums gnome-user-docs | wc -l
4
$ debsums gnome-user-docs | grep 'OK$' | wc -l
4
$ debsums -a gnome-user-docs | grep 'OK$' | wc -l
4
$ debsums gnome-user-docs
/usr/share/doc/gnome-user-docs/NEWS.gz                                        OK
/usr/share/doc/gnome-user-docs/README                                         OK
/usr/share/doc/gnome-user-docs/changelog.Debian.gz                            OK
/usr/share/doc/gnome-user-docs/copyright                                      OK

Whereas on a system without this problem:

$ debsums gnome-user-docs | wc -l
465

and the difference is in the /usr/share/help/C/gnome-help/ and /usr/share/help/C/system-admin-guide/ files: The files I am talking about throughout this post.

I am generally using yelp (the life preserver icon on the desktop) to view system man pages. After I open yelp, I can press Ctrl+L and enter man:man for example to view the man page for the man command.

This works OK. However, the line width is different on each of my Ubuntu installations. For example, the first (physical) line of man man page's DESCRIPTION section in yelp is like this:

Ubuntu 18.04 LTS (Virtual Machine):

man is the system's manual pager. Each page argument given to man is normally the name of

Ubuntu 19.04 (Virtual Machine):

man is the system's manual pager. Each page argument given to man is normally the name of a program, utility or function. The manual page associated with each of these arguments is

Ubuntu 19.04 (Physical Machine):

man is the system's manual pager. Each page argument given to man is normally the name of a program, utility or function. The manual page associated with each of these arguments is then found and displayed. A section, if

As you see, in my desktop (physical machine) man pages are formatted very wide. You can view the page correctly only when the yelp window is maximized. However, when you set it to something half of the screen width, the lines are wrapped and the physical line breaks occur at odd places which is very confusing.

How, can I set yelp to display man pages with say 80-character physical lines?

Note: Setting the MANWIDTH environment variable, works in man command line; but, does not make any change in yelp. For example, the command MANWIDTH=80 yelp man:man still displays wide lines as described above.

I have both Ubuntu 16.04 LTS and Ubuntu 18.04 LTS installed.

I want to search for documentation and read it off-line (as it is included to the installed packages in /usr/share/help and other locations). As far I can understand it has three formats:

• HTML - .page (dpkg -S .page | grep -E /usr/share/help | awk '{print $1}' | sort | uniq | wc -l returns 12 results)
• DocBook - .docbook (dpkg -S .docbook | grep -E /usr/share/help | awk '{print $1}' | sort | uniq | wc -l returns 21 results)
• ManPage (many from manpath = /usr/local/man:/usr/local/share/man:/usr/share/man)

These files are rendered by Yelp program (from yelp package) with executables yelp and gnome-help.

Notes:

1. here on AskUbuntu was similar question about ScrollKeeper database (provided by rarian-compat package) without answer;

2. there is a bug 726439 named "Search for document returns an Unknown error: 'URI xref:search=' could not be parsed" on LauchPad.net (from 2011 year) about broken(?) search in Yelp. If I press CtrlS to search searchterm in current version of Yelp it still returns

   Unknown Error
   The URI ‘xref:search=searchterm’ could not be parsed.

Of course I can run the grep over all these files, but is it possible to run such search from Yelp?

I need some help in understanding how the Yelp Help Browser works. When I start Yelp in Ubuntu 17.10 I get the Ubuntu Desktop Guide, and when I search for terms that should definitely be contained in some of the documentation packages I recently installed, I come up blank.

My understanding (based on this page at gnome.org) is that Yelp uses scrollkeeper's catalogue to generate a table of contents, but it seems that this behaviour is overridden in the Ubuntu distro. Also the Ubuntu version does not have the menus (enabling bookmarking etc.) displayed on the screenshot at that page. When installing the documentation packages I got feedback in the terminal that the package was registered with scrollkeeper. I'll keep searching for an answer, but if you could help out, it would be greatly appreciated.