Quoting Martin McCormick (2019-05-06 21:24:41) > Jonas Smedegaard <jonas@jones.dk> writes: > > > > I recommend to first make sure that the system tracks only packages from > > one single Debian release (not a mixture of multiple releases, and > > certainly not any non-Debian repositories). > > > > (then I'd probably install etckeeper if not done already, to have a way > > of reverting some kinds of accidents in the following steps) > > > > Then I'd check that all packages have fully upgraded and no packages are > > left that in not part of the new system. Several ways to do that - > > personally I prefer using aptitude in fullscreen mode (i.e. start it > > with no non-option arguments) and look first at "Obsolete and Locally > > Created Packages" section, then "Upgradable Packages", and then _all_ of > > "Installed Packages" checking that the version is the one in the current > > system. > > > > Then I'd inspect all packages recommended but not installed. You > > certainly should know for sure that why each and every exception is > > there and that you really don't need it! With aptitude that's done by > > hitting "CTRL+t" and in menu "Views" select "Audit Recommendations". > > > > Then I'd purge all packages not installed. In aptitude that's done by > > standing on the section "Not Installed Packages" and hit "_", and then > > "g" twice (skimming through what the list after first "g" to ensure > > nothing suspicious sticks out). > > > > Then I'd inspect files below /etc - obvous bugs like broken symlinks, > > and unfinished merge of conffiles (look for *.dpkg* files). > > > > > > - Jonas > > Thank you. I appreciate all the suggestions. I have, so far, solved > the immediate problem. It dates back to 2017. A file named > /etc/pam.d/common-session which should be a 26-line configuration file > had been overwritten by nulls. How that happened, I do not remember > but it is not a runtime-created file so I replaced it with a copy of > the same file from the working system and sudo commands now work as > they are supposed to. > > If there turns out to be any more issues, I will use the steps > you suggested plus compare file permissions and ownership of all > related files. Fortunately, all the stretch systems I have are > basically copies of each other. > > Again, many thanks to all who responded. Good you located the cause of the problem. Really frustrating when system doesn't behave reasonable! A file filled with nulls smells badly of filesystem corruption: My guess is you don't ext4 with journalling enabled on that partition... - Jonas -- * Jonas Smedegaard - idealist & Internet-arkitekt * Tlf.: +45 40843136 Website: http://dr.jones.dk/ [x] quote me freely [ ] ask before reusing [ ] keep private
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