Odd failed dependency...

Lamont Peterson lamont at gurulabs.com
Thu Sep 20 16:55:22 UTC 2007

Hash: SHA1

On Thu, 20 Sep 2007 17:29:58 +0200
Thorsten Leemhuis <fedora at leemhuis.info> wrote:

> On 20.09.2007 16:23, Tim Waugh wrote:
> > On Wed, 2007-09-19 at 23:54 +0100, Richard Hughes wrote:
> >> Does the printing config tool call into pirut to install something?
> >>
> >> [root at hughsie-laptop ~]# rpm -e pirut
> >> error: Failed dependencies:
> >> pirut is needed by (installed)
> >> system-config-printer-
> >>
> >> Any ideas of the mechanism if this is the case? Thanks,
> > 
> > It forks system-install-packages.  It's used for installing print
> > drivers.
> I thought there was a "unwritten" policy to install (nearly?) all
> drivers for hardware by default to make sure people can just configure
> hardware even in situations when they don't have a network connection
> or a install CD at hand.

The use of the word "drivers" for printers has nothing to do with hardware drivers.  Actually, for most printers, they're not really "drivers" in the same sense as for other hardware.  There are some printers in the world that have no brains but are merely a collection of motors that need a computer to have a driver that knows how to send all the right signals to them at the right times in order to be able to print (kinda like a "winmodem").  Thankfully, there are very few of these.

Most of the time, a printer "driver" isn't really a driver, but is a filter for the print subsystem (i.e. cupsd) to push the file to be printed through.  Such filters convert, for example, PostScript or plain-text into whatever printer language (like PostScript or PCL) the printer it's headed for understands.

It all boils down to the fact that printer "drivers" are not drivers as in what the kernel provides.

Still, I thought we had lots of printer filter sets (like foomatic) installed by default with CUPS.  Some questions:

1.  What other things might be installed as a consequence of using system-config-printer to set up a printer?
2.  Are they really all that big that it costs users anything significant to just have those installed too?
3.  Or, should we go the other direction and not install quite so many to begin with?
4.  Either way, can't system-config-printer just call yum or tell you to 'Have an admin run "yum install foo" if you want to setup that printer' if pirut isn't installed?

Personally, I'm a fan of Provides: and would like to see more things not depend on otherwise optional components.  If I don't have to have something installed just because I want to use another program but I'll never use the optional features, why be forced into it?  We probably shouldn't talk about that last question in this thread as I think I'm starting to head off-topic for the thread.
- -- 
Lamont Peterson <lamont at gurulabs.com>
Senior Instructor
Guru Labs, L.C. [ http://www.GuruLabs.com/ ]

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