[mythtv-users] mythfilldatabase failing after OS upgrade

Daryl McDonald darylangela at gmail.com
Sat Jan 7 00:52:06 UTC 2023


On Fri, Jan 6, 2023 at 6:49 PM Hika van den Hoven <hikavdh at gmail.com> wrote:

> Hoi Daryl,
>
> Saturday, January 7, 2023, 12:18:00 AM, you wrote:
>
>
>
>
> > On Fri, Jan 6, 2023 at 6:09 PM Mike Perkins
> > <mikep at randomtraveller.org.uk> wrote:
>
> > On 06/01/2023 21:01, Hika van den Hoven wrote:
>  >> Hoi Daryl,
>  >>
>  >> There is one thing you always have to remember when you move data like
>  >> this between old and new systems or even more important, share them
>  >> between two installation on one physical system.
>  >>
>  >> usernames and groupnames are meaningless to the computer. The computer
>  >> uses the numerical u(ser)id and g(roup)id. For our benefit as stupid
>  >> mortals it translates it to a name.
>  >>
>  >> However the translation between the numerical id's and the names is
>  >> unique to every installation, with the only exception of root. Root
>  >> always has a uid of 0 and a gid of 0. Some of the groups have
>  >> generally by agreement the same gid, but they could be another.
>  >>
>  >> So if you create a new installation and want to copy or share data
>  >> with an old installation you have to ensure the involved users and
>  >> groups have the same uid and gid on both installations. You can set
>  >> the uid on user creation (if not already taken by another user).
>  >>
>  >> This is why I use ldap for network wide user and group management. The
>  >> user hika and mythtv have the same uid on all computers and most
>  >> groups likewise.
>  >>
> >  I would add another complication, which I discovered copying a
> > disk from an old backend to a new one
> >  (duff motherboard). Many of the users and groups generated by a
> > fresh install are "system" users;
> >  that means they are usually used only by OS subsystems. These are less
> than 1000 and typically
> >  assigned the next available numbers. As the order of installation is
> indeterminate during an OS
> >  install, these are essentially random and won't match the UIDs and GIDs
> on any other host.
> >
> >  Mythtv as installed from repos is often treated as a "system"
> > install, meaning that the UID and GID
> >  the user "mythtv" is assigned can often collide with UIDs from
> > other subsystems like, for example,
> >  gdm and lxd.
> >
> >  For this reason I now *always* create a mythtv user with a known UID
> and GID in the normal user
> >  range (> 1000) before installing any software. That ensures (i)
> > there are no collisions, (ii) any
> >  existing video files still have the right UID and GID, (iii) the
> > user is created under /home rather
> >  than under /var, and (iv) if I access those directories from
> > elsewhere I get sensible answers from NFS.
> >
> >  --
> >
> >  Mike Perkins
>
>
> > So, in my case, with a clean install of 22.04/32 on a separate
> > partition of the 120GB OS ssd and a database restore from 20.04/31
> > there are bound to be these kinds of issues? Unless I'm one in one
> thousand lucky, ouch.
> >
> >
> Yes, and the smartest move would be to start over your 22.04 install
> and this time create the mythtv and daryl user as the first thing
> after you created the basic install and before you install any other
> software and with the same uid as on your 20.04 install.
> If you haven't copied over much you can try to repair, but chances are
> you either fix to much or to little and stumble into it again in 6
> months or so.
>
> I don't have the commands ready at hand as I rarely use them, but I
> can look it up.
>
>
> Tot mails,
>   Hika                            mailto:hikavdh at gmail.com
>
> "Zonder hoop kun je niet leven
> Zonder leven is er geen hoop
> Het eeuwige dilemma
> Zeker als je hoop moet vernietigen om te kunnen overleven!"
>
> De lerende Mens
>
Okay, so how do I determine the UID's from 20.04, and if I can do that why
can't I manipulate the UId's in 22.04 ?

>
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