symlinks breaks lsb_release, but diff reports no changes?

[Jeffrey Walton]

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!

Jeff