Re: is dpkg install atomic?
On Tue, Oct 26, 2021 at 10:31:54AM -0700, Han wrote:
> Hi,
> This might be a dumb question: is dpkg installing (or updating) a package
> using a .deb file atomic in the event of power outage?
> By atomic, I meant either the new version of the application is fully
> installed, or not at all. Is this always guaranteed?
> I read the `man dpkg` doc, but couldn't find a clear answer. I might have
> missed it though.
> Thanks,
> Han
It's not a dumb question. The installation of a package might seem,
from the user perspective, like it could be atomic, but it is really
made up of a variety of steps.
Broadly, the package is downloaded, then unpacked, then any included
pre-installation script is executed, the unpacked contents are placed in
their location on the system, and then any included post-installation
script is executed. A power outage at any point in the process could
leave the package in a state where is it is not fully installed.
Though, generally speaking, a situation like that can almost always be
recovered from by a command like 'apt-get install --reinstall <pkg>'.
However, there might circumstances where more advanced techniques might
be required.
Regards,
-Roberto
--
Roberto C. Sánchez
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