Developer forum

Re: Subtle difference in behavior of installation packages

John Pietrzak — Fri, 10 Feb 2012 02:30:06 +0000

On 2/9/12 6:30 PM, gregor herrmann wrote:

On Wed, 08 Feb 2012 18:38:53 -0500, John Pietrzak wrote:

BTW, what is Debian's purpose on keeping conffiles around? Is there value in having config info for nonexisting packages? (Should I not be worried about leaving sudoers files in the sudoers.d directory?) A package might be removed only temporarily or in error, and be reinstalled again later. In that case the admin will be happy to find their carefully tweaked config files instead of having to re-create them from scratch (or grab them from a backup or an older git revision). And in general conffiles lying around in /etc/ don't hurt.

Ah, I guess that makes sense.

Thanks!

--John

Re: Subtle difference in behavior of installation packages

gregor herrmann — Thu, 09 Feb 2012 23:30:27 +0000

On Wed, 08 Feb 2012 18:38:53 -0500, John Pietrzak wrote:

apt-get remove without --purge won't remove conffiles, which would explain why /etc/sudoers.d/foo is still there ... And that's on purpose at least in Debian. BTW, what is Debian's purpose on keeping conffiles around? Is there value in having config info for nonexisting packages? (Should I not be worried about leaving sudoers files in the sudoers.d directory?)

A package might be removed only temporarily or in error, and be reinstalled again later. In that case the admin will be happy to find their carefully tweaked config files instead of having to re-create them from scratch (or grab them from a backup or an older git revision). And in general conffiles lying around in /etc/ don't hurt.

Cheers, gregor

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Re: Subtle difference in behavior of installation packages

John Pietrzak — Wed, 08 Feb 2012 23:38:53 +0000

On 2/8/12 3:15 PM, Pali Rohár wrote:

On Wednesday 08 February 2012 21:04:26 gregor herrmann wrote:

apt-get remove without --purge won't remove conffiles, which would explain why /etc/sudoers.d/foo is still there ...

And that's on purpose at least in Debian. If HAM can't be told to purge a package there's not much that can be done (short of using brute force in the postrm maintainer script. Ehh, this sounds ugly.).

Yes, I tried the brute-force approach, and it was ugly. Ended up with the package manager thinking the sudoers file still existed. :(

BTW, what is Debian's purpose on keeping conffiles around? Is there value in having config info for nonexisting packages? (Should I not be worried about leaving sudoers files in the sudoers.d directory?)

You can create sudoers.d file in postinst file and remove it in postrm. echo "..."> /etc/sudoers.d/...

Thanks, tried that out, and it works fine! I guess I'll just go with that for now...

Thanks,

--John

Re: Subtle difference in behavior of installation packages

Pali Rohár — Wed, 08 Feb 2012 20:15:12 +0000

On Wednesday 08 February 2012 21:04:26 gregor herrmann wrote:

On Wed, 08 Feb 2012 19:21:16 +0100, Pali Rohár wrote:

I can install and uninstall the file just fine using the debian package I've constructed locally. When installing the app from the Extras-Devel repository, however, the application manager can place the file into /etc/sudoers.d, but seems unable to remove it when uninstalling.

Try to run apt-get remove in xterm. This is what application manager doing... Also see error in application manager log.

apt-get remove without --purge won't remove conffiles, which would explain why /etc/sudoers.d/foo is still there ...

And that's on purpose at least in Debian. If HAM can't be told to purge a package there's not much that can be done (short of using brute force in the postrm maintainer script. Ehh, this sounds ugly.).

Cheers, gregor

You can create sudoers.d file in postinst file and remove it in postrm. echo "..." > /etc/sudoers.d/...

Or you can force debhelper to not add that sudoers file to conffiles.

-- Pali Rohár pali.rohar@gmail.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux)

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Re: Subtle difference in behavior of installation packages

gregor herrmann — Wed, 08 Feb 2012 20:04:26 +0000

On Wed, 08 Feb 2012 19:21:16 +0100, Pali Rohár wrote:

I can install and uninstall the file just fine using the debian package I've constructed locally. When installing the app from the Extras-Devel repository, however, the application manager can place the file into /etc/sudoers.d, but seems unable to remove it when uninstalling. Try to run apt-get remove in xterm. This is what application manager doing... Also see error in application manager log.

apt-get remove without --purge won't remove conffiles, which would explain why /etc/sudoers.d/foo is still there ...

And that's on purpose at least in Debian. If HAM can't be told to purge a package there's not much that can be done (short of using brute force in the postrm maintainer script. Ehh, this sounds ugly.).

Cheers, gregor

-- .''`. Homepage: http://info.comodo.priv.at/ - OpenPGP key 0xBB3A68018649AA06

:' : Debian GNU/Linux user, admin, and developer - http://www.debian.org/ .' Member of VIBE!AT & SPI, fellow of the Free Software Foundation Europe `- NP: Carole King: Will You Still Love Me Tomorrow

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Re: Subtle difference in behavior of installation packages

Pali Rohár — Wed, 08 Feb 2012 18:21:16 +0000

Hi,

On Wednesday 08 February 2012 13:10:25 John Pietrzak wrote:

Hi folks,

I've been working on a small Maemo app, and have reached the point where I've pushed it up to Extras-Devel. Almost everything works perfectly, except for one item: I've created a sudoers file for the app, in order to allow it to call "modprobe" to load a kernel module. (This is the "lirc_rx51" module, needed for access to the IR hardware.) This file needs to go into the /etc/sudoers.d directory.

I can install and uninstall the file just fine using the debian package I've constructed locally. When installing the app from the Extras-Devel repository, however, the application manager can place the file into /etc/sudoers.d, but seems unable to remove it when uninstalling.

Try to run apt-get remove in xterm. This is what application manager doing... Also see error in application manager log.

I'm using the Qt SDK, and have recently upgraded to Qt Creator 2.4.1, so maybe the latest Qt software creates debian packages differently than the Extras system does...

So, I guess these are my questions:

1) Do I need to do something special to install/uninstall files to the /etc directory in Maemo?

I think nothing special. Only add your /etc files to conffiles in debian package, but this is done by debhelper script for dpkg-buildpackage. So really nothing.

2) Should I even be using /etc/sudoers.d to let my app access modprobe? What is the preferred way for an app to make requests of the kernel?

Yes add sudoers file, run script for updating sudoers.d and use: sudo modprobe

Thanks!

--John

-- Pali Rohár pali.rohar@gmail.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux)

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Subtle difference in behavior of installation packages

John Pietrzak — Wed, 08 Feb 2012 18:10:25 +0000

Hi folks,

I've been working on a small Maemo app, and have reached the point where I've pushed it up to Extras-Devel. Almost everything works perfectly, except for one item: I've created a sudoers file for the app, in order to allow it to call "modprobe" to load a kernel module. (This is the "lirc_rx51" module, needed for access to the IR hardware.) This file needs to go into the /etc/sudoers.d directory.

I can install and uninstall the file just fine using the debian package I've constructed locally. When installing the app from the Extras-Devel repository, however, the application manager can place the file into /etc/sudoers.d, but seems unable to remove it when uninstalling.

I'm using the Qt SDK, and have recently upgraded to Qt Creator 2.4.1, so maybe the latest Qt software creates debian packages differently than the Extras system does...

So, I guess these are my questions:

1) Do I need to do something special to install/uninstall files to the /etc directory in Maemo?

2) Should I even be using /etc/sudoers.d to let my app access modprobe?
What is the preferred way for an app to make requests of the kernel?

Thanks!

--John

Re: Resources for learning Qt on Mameo5 Fremantle

Johan Helsingius — Wed, 08 Feb 2012 07:41:23 +0000

Thanks, I will see if I can track down that book (ordering it from Amazon is an option but the shipping to Australia is a killer :)

It seems to be available as an ebook.

http://www.wowebook.me/book/beginning-nokia-apps-development/

Julf

Re: Resources for learning Qt on Mameo5 Fremantle

Jonathan Wilson — Wed, 08 Feb 2012 00:41:44 +0000

That book is fine, but is focused on desktop. There are a couple of books out there focused on Qt and mobile apps. "Beginning Nokia Apps Development" is about Qt on Symbian and MeeGo and can be had for under $10 USD. Thanks, I will see if I can track down that book (ordering it from Amazon is an option but the shipping to Australia is a killer :)

Re: Resources for learning Qt on Mameo5 Fremantle

Paul Hartman — Tue, 07 Feb 2012 16:52:12 +0000

On Tue, Feb 7, 2012 at 10:22 AM, Jonathan Wilson jfwfreo@tpgi.com.au wrote:

I am looking for resources related to learning Qt on Maemo5 Fremantle. More specifically I am trying to understand the workings of this app: (and add some new features to it such as a one-step undo for when you press the wrong block by mistake) http://maemo.org/packages/view/skidstone/

I have a copy of a book titled "C++ GUI Programming with Qt 4 Second Edition", will the information in that book be of any use in understanding whatever version of QT Maemo5 has? Where can I find tutorials and things dealing with mobile-specific stuff like touch events?

That book is fine, but is focused on desktop. There are a couple of books out there focused on Qt and mobile apps. "Beginning Nokia Apps Development" is about Qt on Symbian and MeeGo and can be had for under $10 USD.

Also of course the great documentation on the Qt website itself cannot be overlooked. :)