thank you very much David Wright: > On Sat 11 Feb 2017 at 12:35:00 (+0000), GiaThnYgeia wrote: >> Jimmy Johnson: >>> On 02/10/2017 05:49 PM, David Wright wrote: >>>> On Fri 10 Feb 2017 at 16:00:13 (-0800), Jimmy Johnson wrote: >>>>> Hello, >>>>> Take a look at Synaptic Menu you can select a package and then go to >>>>> Package > Force Version, you can only force one package at a time >>>>> but, yes you can downgrade. I can down grade a couple hundred >>>>> packages without much problem, depends on the user. >>>> >>>> Oh, that's heartening! Does Synaptic use a different method >>>> from dpkg? The man page for the latter says (and the warnings >>>> look very pretty in red): >>>> Warning: At present dpkg does not do any dependency checking on >>>> downgrades and therefore will not warn you if the downgrade >>>> breaks the dependency of some other package. This can have seri‐ >>>> ous side effects, downgrading essential system components can >>>> even make your whole system unusable. Use with care. >>>> Cheers, >>>> David. >>> >>> Hi David, Synaptic will not let you install a broken package. If you >>> are running sid/testing sometimes a package version will become obsolete >>> and need a change or a video driver version is not working and needs a >>> change, etc. If you're running in a GUI Synaptic is handy to have >>> installed. And yes, it's using "dpkg". >> >> One thing I have not been able to find in synaptic or elsewhere is a way >> to keep track of what has been installed and when. If you know where >> such a log habitates or can be created let me/us know. > > I use aptitude rather than synaptic so you'll have to compensate for > that in what follows. There are three logs that I use. > > The first is /var/log/aptitude.log which is rotated for only six > months. (I don't think I've changed any log rotation parameters.) > This only shows what you told aptitude itself to do, and only your > intentions, not the results (which might have been unsuccessful). > It also doesn't bother about versions, only package names. > > The second was mentioned and is /var/log/apt/history.log which is > rotated for twelve months. This includes changes made with both > aptitude and apt-get, and it includes the previous and new version > numbers. That makes it messy to parse as you have to deal with > two levels of commas: ... pkga (ver1, ver2), pkgb (ver3, ver4), ... > > The third is /var/log/apt/term.log (also twelve months) which logs > all the results of apt's work, but lacks any of your input. So you > need to look at the other logs to find out why apt did what it did. > It's very long-winded because it even includes the "progress bars". > >> I understand it all relates to what depends on what and who is breaking >> whom. If it is a package that depends on other "stuff" but nothing >> depends on it you can install something from debian1 in its beta version >> and all else is fine. But if you go one version back of one little >> thing that 100 things depend on, you may get 90 things not working. >> This is my simplistic understanding. Out of my panic experimentation I >> have run into situations that it becomes a great puzzle of why the >> system is still working. Like creating a mess and breaking the system >> then reinstalling an earlier version of the distribution ON TOP of the >> mesh, same root and user names and passwords, >> then try to locate all the things that had been installed and upgraded >> that are not on the dpkg list and if not recovered they will remain >> unupdated. And it works! Like magic! I think all synaptic does is >> simplifying and remembering all the correct syntax of dpkg commands and >> executing them for you. > > Well, I'd be interested to see the term.log from a session where > someone downgrades "a couple hundred packages without much problem" > as reported above. According to your experience, their statement of > "depends on the user" is untrue. Synaptic just sorts it all out for > you, though that's surprising in view of your last sentence. > > I have little experience of downgrading, but have read plenty of > postings here about how difficult it can be. I would want a solid > backup system in place at the time, particularly if I were paying > bills with the work. In the past I always depended on having duplicate > systems and some bash scripts to get from the debian-installer to a > working system in short order. > > Cheers, > David. >
-- "The most violent element in society is ignorance" rEG
