Wasn't linux (also) all about acomplishing one task in many different ways?


Leo Custodio
[EMAIL PROTECTED]
http://members.rogers.com/aliensprite/

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> ----- Original Message -----
> From: "Benedict Verheyen" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, February 19, 2004 6:13 PM
> Subject: what's the use of dselect
>
>
> > Hi,
> >
> > I admit i'm a little confused as to what the use is of dselect when
> > we have tools like aptitude and apt-get.
> > Off course, if you like dselect, stop reading ;)
> > I don't like it so i try to use other tools to accomplish the same
> > stuff you can do with dselect.
> > To try to figure this out,i looked at dselect, dpkg, apt-get and
aptitude.
> > According to the manpages of the aformentioned packages, the tools
> > match up like this:
> >
> > Package Manager: dpkg
> > Backend Tool: apt-get
> > Frontend Tools: dselect, aptitude, synaptic, etc
> >
> > By looking at the manpages, i first looked at what files the tools
> > use:
> >
> > 1) Dpkg
> > /var/lib/dpkg/status:        status of packages
> > /var/lib/dpkg/available:     available packages
> >
> > 2) Apt
> > /var/lib/apt/lists:          available packages
> > /var/cache/apt/archives:     saved/cached packages
> >
> > 3) Dselect
> > /var/lib/dpkg/available
> >
> > 4) Aptitude
> > /var/lib/aptitude/pkgstatus  status of packages
> >
> > 1. Now, the manpage of apt-get says this about /var/lib/apt/lists
> > "/var/lib/apt/lists/
> > Storage area for state information for each package resource specified
> > in sources.list(5) Configuration Item: Dir::State::Lists. "
> > This seems to be incorrect as the files in that dir seem to be
> > about what packages are available on what location and not what
> > the status of the package is on the system.
> >
> > 2. /var/lib/dpkg/available seems the same as /var/lib/apt/lists.
> > But to get the same in both files, you also need to do a
> > dselect update (as opposed to a apt-get update)
> >
> > 3. Something that wasn't clear for me: where does an "apt-cache policy"
> > command gets it's info?
> >
> > 4. If you do an "apt-get update", then i think aptitude knows
> > about the updated lists.
> >
> > So as to what is the use of dselect:
> >
> > For the common daily use, apt-get and aptitude seem to do the job.
> > The only situation i can think of where you'll need dselect is
> > after a dpkg --set-selections < myselection.
> > Because this changes the status of the packages and thus the
> > /var/lib/dpkg/status file. "apt-get dselect-upgrade" is the
> > command you should run to update the system and not
> > "apt-get dist-upgrade".
> >
> > Why can't use apt-get in this situation (well according to me)?
> > Because apt-get doesn't use the file /var/lib/dpkg/status.
> > So it will probably just upgrade the system and not install
> > for instance the new packages that where set by
> > dpkg --set-selections.
> >
> > But, in order to do this correctly, you'll have to make sure
> > that your sources.list matches the one from the source system
> > (to have the same packages available) and that you've done
> > a dselect update. That will make sure /var/lib/dpkg/available
> > is in working order.
> > apt-get dselect-upgrade then calls dselect to install the
> > packages. So the versions of the available packages need to be
> > known before we can change their status with dpkg --set-selections.
> >
> > So if the above is true, wouldn't it make sense for apt-get
> > to do like dselect and use /var/lib/dpkg/available or would that
> > typically be more of a job for a frontend tool like aptitude?
> > If so, is there a similar command in aptitude for
> > "apt-get dselect-upgrade" ? Or does it also use dselect to do this?
> > It wouldn't make sense that if those tools are ment to replace
> > dselect that they would still use dselect for some stuff.
> > And frankly i find it confusing :)
> >
> > Any comments are appreciated.
> >
> > Benedict
> >
> >
> > --
> > To UNSUBSCRIBE, email to [EMAIL PROTECTED]
> > with a subject of "unsubscribe". Trouble? Contact
> [EMAIL PROTECTED]
> >
>



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