Score:1

Ubuntu

Is a .deb package's postinst script guaranteed to run when upgrading to a new version of Ubuntu?

Harry Williams

8/4/24, 7:19 PM

My .deb package contains a postinst script that modifies the package depending on the user's operating system.

I would like to make sure that this postinst script is re-run when the user upgrades their version of Ubuntu. Is this guaranteed to happen, or do I need to configure the script to ensure that it is run again?

162

2 + 2

upgrade

package-management

dpkg

Archisman Panigrahi

8/4/24, 7:31 PM

It is a good idea to remove all PPAs/foreign packages before upgrading, and add/install them once again afterwards

Harry Williams

8/4/24, 7:36 PM

That makes sense from the user's perspective, but I want this package to work even if the user doesn't uninstall it before upgrading.

Score:4

Ubuntu

user535733

8/4/24, 7:41 PM

A postinst script runs when that particular package is installed or upgraded.

It does not run at any other time.

The usual method to ensure that the script runs during a release-upgrade is to upgrade the package by bumping the version number.

So...

 Release A = Version 1.1a
 Release B = Version 1.1b (still version 1.1, but different to apt)
 Release C = Version 1.2a (new upstream release version 1.2)

Yes, this means that you are maintaining multiple versions. But in a Debian-based system, that's the simplest solution. There are alternatives using other packaging systems, each with their own advantages and disadvantages.

+ 4

Harry Williams

8/4/24, 8:11 PM

Thank you for the background. I'm a little confused about how I would update the version number on release-upgrade though. Could you please point me to a resource for that?

user535733

8/4/24, 8:23 PM

Changing the version number that apt sees is just a change to your deb's control file.

Harry Williams

8/4/24, 8:50 PM

I meant how would I automatically increment the version number when the user upgrades their OS. To be clear, I'm hoping that the user will *not* have to reinstall the application when they update their OS.

user535733

8/4/24, 9:05 PM

Let's take a step back. Your original question asked specifically about a `postinst` script. But now you're trying to follow up with basic questions about how repositories and control files work. I'm smelling a possible [XY Problem](https://en.wikipedia.org/wiki/XY_problem). Why not ask a new question about the best way to achieve the system customizations that you want to happen? There might be a better way than using postinst.

Score:0

Ubuntu

Marco

8/5/24, 9:14 AM

In best case you can put a trigger on "/etc/os-release" in your package, which triggers your package whenever this file is changed by another package.

This does not work if a package changes "/etc/os-release" in a pre/post-script or via mechanisms like "ucf" or "config-package".

As "/etc/os-release" is part of the package "base-files" the trigger usually works as expected.

+ 0

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EN: Is a .deb package's postinst script guaranteed to run when upgrading to a new version of Ubuntu?

Post an answer

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