On testing, I ran:
sudo apt-get install usrmerge
In hindsight, this was a mistake...
It aborted partway through with:
Both /lib/x86_64-linux-gnu/libpng12.so.0 and
Now my system is very unwell...
su does not work:
su: error while loading shared libraries: libpam_misc.so.0: cannot open
shared object file: No such file or directory
It looks like libpam_misc.so has been partly moved:
/lib/x86_64-linux-gnu/libpam_misc.so.0 is a broken link pointing to
Since su is setuid, I cannot fix this with eg LD_LIBRARY_PATH.
sudo does not work:
sudo: unknown uid 1000: who are you?
At the moment, I don't know how to fix this. I have no root sessions open on
the machine, so I cannot eg simply move libpam_misc.so.