symlinks breaks lsb_release, but diff reports no changes?

[Jeffrey Walton]

On Thu, Dec 18, 2025 at 11:43 AM Jeffrey Walton <noloader at gmail.com> wrote:
>
> On Wed, Dec 17, 2025 at 1:03 PM Jeffrey Walton <noloader at gmail.com> wrote:
> >
> > On Mon, Dec 15, 2025 at 12:21 PM Jeffrey Walton <noloader at gmail.com> wrote:
> > >
> > > I'm seeing an issue on Ubuntu 22.04.5 LTS that I can't explain.
> > > Below, symlinks breaks lsb_release, but a diff of before/after reports
> > > no changes.  Any help would be appreciated.
> > >
> > > First, lsb_release works:
> > >
> > > $ lsb_release -a
> > > LSB Version:    core-11.1.0ubuntu4-noarch:security-11.1.0ubuntu4-noarch
> > > Distributor ID: Ubuntu
> > > Description:    Ubuntu 22.04.5 LTS
> > > Release:        22.04
> > > Codename:       jammy
> > >
> > > Second, run symlinks script (as root):
> > >
> > > #!/usr/bin/env bash
> > >
> > > symlinks -r / 1>symlinks.1.txt
> > >
> > > for dir in /bin /etc /home /lib /lib32 /lib64 /media /mnt /opt /root
> > > /run /sbin /srv /tmp /usr /var;
> > > do
> > >     # Ensure the directory exists
> > >     test -d "${dir}" || continue
> > >     # Skip directories that are tmpfs
> > >     df -hT "${dir}" | grep -q tmpfs && continue
> > >     # echo "  dir: ${dir}"
> > >     symlinks -r -d "${dir}" 1>/dev/null
> > > done
> > >
> > > symlinks -r / 1>symlinks.2.txt
> > >
> > > Third, try lsb_release again:
> > >
> > > $ lsb_release -a
> > > Traceback (most recent call last):
> > >   File "/usr/bin/lsb_release", line 25, in <module>
> > >     import lsb_release
> > > ModuleNotFoundError: No module named 'lsb_release'
> > >
> > > Fourth, diff the changes from symlinks:
> > >
> > > $ diff symlinks.1.txt symlinks.2.txt
> > > $
> > >
> > > Fifth, reinstall lsb-release package:
> > >
> > > $ sudo apt install --reinstall lsb-release
> > >
> > > Sixth, recheck lsb_release:
> > >
> > > $ lsb_release -a
> > > LSB Version:    core-11.1.0ubuntu4-noarch:security-11.1.0ubuntu4-noarch
> > > Distributor ID: Ubuntu
> > > Description:    Ubuntu 22.04.5 LTS
> > > Release:        22.04
> > > Codename:       jammy
> > >
> > > One clue is from dpkg, but I don't know if it is a red herring:
> > >
> > > $ dpkg -L lsb-release
> > > ...
> > > /usr/share/pyshared
> > > /usr/share/pyshared/lsb_release.py
> > > /usr/lib/python2.7/dist-packages/lsb_release.py
> > > /usr/lib/python3/dist-packages/lsb_release.py
> > >
> > > And:
> > >
> > > $ ls /usr/share/pyshared
> > > lsb_release.py
> > > $ ls /usr/share/pyshared/lsb_release.py
> > > /usr/share/pyshared/lsb_release.py
> > > $ ls /usr/lib/python2.7/dist-packages/lsb_release.py
> > > ls: cannot access '/usr/lib/python2.7/dist-packages/lsb_release.py':
> > > No such file or directory
> > > $ ls /usr/lib/python3/dist-packages/lsb_release.py
> > > ls: cannot access '/usr/lib/python3/dist-packages/lsb_release.py': No
> > > such file or directory
> > >
> > > $ ls -d /usr/lib/python*
> > > /usr/lib/python2.7  /usr/lib/python3  /usr/lib/python3.10  /usr/lib/python3.11
> > >
> > > And:
> > >
> > > $ sudo find /usr/lib -name lsb_release.py
> > > $
> > >
> > > I am missing something.  Does anyone know what is going on?
> >
> > I tracked it down to a symlink that goes missing.  But I don't
> > understand why symlinks does not report it as a dangling link, and
> > then why symlinks deletes it.
> >
> > First, start with a working lsb_release:
> >
> > LSB Version:    core-11.1.0ubuntu4-noarch:security-11.1.0ubuntu4-noarch
> > Distributor ID: Ubuntu
> > Description:    Ubuntu 22.04.5 LTS
> > Release:        22.04
> > Codename:       jammy
> >
> > Second, check the Python3 lsb_release (from dpkg -L symlinks):
> >
> > $ ls -Al /usr/lib/python3/dist-packages/lsb_release.py
> > lrwxrwxrwx 1 root root 38 Mar 24  2022
> > /usr/lib/python3/dist-packages/lsb_release.py ->
> > ../../../share/pyshared/lsb_release.py
> > $ ls /usr/share/pyshared/lsb_release.py
> > /usr/share/pyshared/lsb_release.py
> >
> > Third, see what symlinks says about it:
> >
> > $ sudo symlinks -r / | grep lsb
> > $ sudo symlinks -r /usr | grep lsb
> > $ sudo symlinks -r /usr/lib | grep lsb
> > $
> >
> > Fourth, clean symlinks:
> >
> > [See script above]
> >
> > Fifth, check lsb_release again:
> >
> > Traceback (most recent call last):
> >   File "/usr/bin/lsb_release", line 25, in <module>
> >     import lsb_release
> > ModuleNotFoundError: No module named 'lsb_release'
> >
> > Sixth, check the lsb_release symlink again:
> >
> > $ ls -Al /usr/lib/python3/dist-packages/lsb_release.py
> > ls: cannot access '/usr/lib/python3/dist-packages/lsb_release.py': No
> > such file or directory
> > $ ls /usr/share/pyshared/lsb_release.py
> > /usr/share/pyshared/lsb_release.py
> >
> > So it looks like symlinks silently deleted the symlink
> > /usr/lib/python3/dist-packages/lsb_release.py.  symlinks never
> > reported it as a symlink, and did not report it was deleted when
> > symlinks was run with the -d option.  Bad tool!
> >
> > I guess this should be reported to the Ubuntu folks.
>
> The missing two pieces are: (1) symlinks needs to be run with `-v`
> option to view relative links; and (2) symlinks is deleting relative
> links that are _not_ reported as dangling.
>
> So this will generate the proper diff file:
>
> symlinks -v -r / 1>symlinks.1.txt
>
> # Avoid special filesystems, like /boot, /dev, /proc and /sys
> for dir in /bin /etc /home /lib /lib32 /lib64 /media /mnt /opt /root
> /run /sbin /srv /tmp /usr /var;
> do
>     # Ensure the directory exists
>     test -d "${dir}" || continue
>     # Skip directories that are tmpfs
>     df -hT "${dir}" | grep -q tmpfs && continue
>     # echo "  dir: ${dir}"
>     symlinks -r -d "${dir}" 1>/dev/null
> done
>
> symlinks -v -r / 1>symlinks.2.txt
>
> And then diff'ing the files:
>
> $ diff symlinks.1.txt symlinks.2.txt
> 3637d3636
> < relative: /usr/lib/python2.7/dist-packages/lsb_release.py ->
> ../../../share/pyshared/lsb_release.py
> 7345d7343
> < relative: /usr/lib/python3/dist-packages/lsb_release.py ->
> ../../../share/pyshared/lsb_release.py
>
> Notice symlinks deleted relative links, not dangling links.  Bad tool!

The issue was reported to Ubuntu at
<https://bugs.launchpad.net/ubuntu/+source/symlinks/+bug/2136999>.

Jeff