Cups - job cancellation - group membership is the key

There are several printing systems which you might use in Debian, depending on your desktop of choice (Xfce, KDE, Gnome, Lxde, etc)

If you use cups, then one of the tasks you will want, at some point, is "Job cancellation"

When this task is first required, I find myself immediately leaping to the following questions:

What port is the cups 'admin interface' running on so I can open the admin web page in a browser?

...and...

Do I enter admin / root where the authentication prompt asks for "User Name"?

...and...

Where in /etc/ can I find the password for the admin / root user?

...and lastly I am probably about to head out to websearch for 'cups admin default password'


Turns out I am asking all the wrong questions and wasting my time.


How to do Job cancellation in cups:

( should not require a 'sign-in' - the key is group membership )

On a multi-user system, not all users will necessarily have access to a printer.
( It could be that your "Industrial Colour Laser 9000" is not something you want every team in the office to be able to access )

If your OS of choice has a 'server distribution' and 'desktop distribution' (Ubuntu perhaps or the Red Hat / Fedora combination), then some might feel it is appropriate for the 'desktop' version to have automatic membership of lpadmin.

Once your username is a member of lpadmin, then you can proceed to this screen:

Which will list the queued jobs and offer you the option to 'Cancel' for each job in the queue*.

( Url is http://localhost:631/jobs/ which you can bookmark in your browser )

*Note: you might have to log out & log back in again, in order for the new group membership to take effect, then afterwards access http://localhost:631/jobs/


GNU / Linux has several options for backend printing systems, as I hinted earlier.

If you prefer a different printing backend, then, for Xfce, the settings here:

...and here ...

...will help you switch to an alternative.


Notes and Further reading:

Cups is not universally liked, and different GNU / Linux distributions use more or less of it to their taste.

Quoting from a Red Hat printing tutorial, two advantage of cups are:

1. Available on all versions of Unix.
2. Can be accessed from a terminal using a text based web browser (such as links).

Personally I quite like the idea of http://localhost:631/ in a browser for printer control, seems simple and it works. So I do not mind a quick manual group add command, in order to set things up my end :)

debian squeeze - xfce panel disappeared?

Debian squeeze, is a debian version that I joined early.

In choosing to use 'beta' software, you will run across an occasional bug.

Mine was the loss of the xfce panel, which did cause me an issue for an hour or so.

Debian production releases are generally very good, so do only choose to play 'beta' if you are prepared for a hiccup once in a while.



Loss of xfce-panel, the cause, and how to fix:

The probably cause was using a KDE application when my desktop is Xfce.
( Often this is not an issue, but sometimes it is. )

In short I installed choqok identica client, even though I do not run a KDE desktop (more on this later)

The big problem:

The application failure killed the program xfce-panel and I had no obvious way to restart it!

Help! my xfce panel is missing!

The fix (seems obvious now):

Open a terminal and start xfce4-panel manually.

 

( The untidy output from xfce4-cpugraph-plugin can be ignored as noise )

The permanent fix / check:

Xfce session can be set to always start 'xfce4-panel', and probably should be this way by default:

Session shows you what is running and the 'Restart Style'

Ensure (using the Application Autostart tab) that xfce4-panel is set to 'Immediately'

Once this is set to 'Immediately', you should be safe in the knowledge that a simple reboot will create a new session that autostarts xfce4-panel.

It should not take the loss of your panel to have such a desirable setting, but at least now you know where these sort of things are located :)

Xfce Menu --> Settings --> Session and Startup

( Above is where you will find how to change those preferences shown above )

Final Gotcha and Kiosk mode:

There are two ways of saving the session - (1) Shown above the 'Save Session' button within the Startup list screen
...and...
(2) The ticked box during Logout 'save session' prompt

Because you have started xfce4-panel from a terminal, then pressed 'Save Session' button, then most likely killed the terminal with (X)....

...if you then have 'save session' ticked when you see the logout prompt, then you will have undone all your good work!

Just this once, ensure you logout with NO TICK when the logout prompt is displayed.

But none of this worked for me as I just kept getting warnings about kiosk mode?

There is a bug in the beta for Debian 7 (wheezy) which seems to trigger kiosk mode if you attempt to manually start the panel from the clickable menu, rather than as I suggested (from a terminal).

If you get warnings about Kiosk mode, then recap on my instructions above, and avoid starting the panel by clicking a drop down menu - DO IT via TERMINAL


Xfce users running KDE and Gnome programs:

In short your mileage will vary.

You can go some way to having maximum compatibility by installing the entire KDE and Gnome libraries and desktop. Although this sort of defeats the object of running an Xfce 'light' installation!

You should maybe consider having these checkboxes ticked:

If you find yourself worrying about this kind of thing often, then perhaps you really should be running a full KDE or Gnome desktop in the first place.

Xfce is an excellent desktop, however it really depends on how _you_ use your computer. If it is not for you then try an alternative. At least with GNU / Linux you have these choices available to you :)


Notes and Further reading:

Would my issue have occurred had I not been using 'beta' software? Maybe, but it is hard to say for sure otherwise.

Would my issue occur, if I choose to play nicely, and start all the services that KDE relies upon in every session? Probably.

( If I have made this sound in any way like it is KDEs fault, then that is not my intention in this article. My aim was merely to introduce a discussion about compatibility based on an individual experience. )

• Xfce project - about [ www.xfce.org ]
• Xfce panel description and detail [ www.xfce.org/projects/ ]
• Version 4 of Xfce described on Wikipedia
• Thunar file manager is 'light' on memory [ thunar.xfce.org ]
  

My install log of choqok, showing the version which I think was not entirely happy with my 'light' Xfce environment:

2010-12-02 20:50:52 install choqok  0.9.81-3
2010-12-02 20:50:52 status half-installed choqok 0.9.81-3
2010-12-02 20:50:52 status half-installed choqok 0.9.81-3
2010-12-02 20:50:52 status half-installed choqok 0.9.81-3
2010-12-02 20:50:52 status half-installed choqok 0.9.81-3
2010-12-02 20:50:53 status unpacked choqok 0.9.81-3
2010-12-02 20:50:53 status unpacked choqok 0.9.81-3
2010-12-02 20:50:57 configure choqok 0.9.81-3 0.9.81-3
2010-12-02 20:50:57 status unpacked choqok 0.9.81-3
2010-12-02 20:50:57 status half-configured choqok 0.9.81-3
2010-12-02 20:50:57 status installed choqok 0.9.81-3

LibreOffice and 'variant' OpenOffice writing formats

In truth, I know very little about LibreOffice as it is a new project, with new sign on, and has yet to decide it's own goals and morals.

What I would like of LibreOffice is a non-Oracle managed, truly free office suite.

I feel that instead I will be disappointed, however, that is probably my faulty expectation, which already is likely out of step with the project.

Reading the LibreOffice 'ooxml writing' discussions last night was useful, I learned something that raised some questions for me.

Seems that it is the go-oo.org version of OpenOffice that is now in debian (with ooxml write capability).
Did this happen just because somebody complained about the 'Oracle' logo on startup screen? I do not know.

What I do know is the result: Now that go-oo.org variant is in Debian, this fact is now being used by some, as argument for ooxml writing to be included in the default install for LibreOffice (argument not won quite yet).

LibreOffice has Google and Canonical ?financial? backing, and whilst I like some of what Google does, I do not forget that they are a huge corporation with billion dollar revenue. Compatibility is utmost probably in what both Canonical and Google want, and software freedom, probably lists somewhere lower down.

In the last couple of months there have been two mistakes I think:
  (1) Debian project being so eager to pull code from go-oo.org, without considering that in providing ooxml writing code by default, the project has made a choice on behalf of users.
  (2) My expecting LibreOffice to be more resistant to taint than existing free office projects.

If debian can have an emacs23-nox and a full fat emacs23, can it not simply have openoffice.org-dfsg and openoffice.org-odf-ooxml, with the later including provisional ooxml writing support?
In my opinion this would be much more convenient than having a user fiddle with xcu/xcs config files.

Should the existing debian packages be renamed go-oo.org rather than openoffice.org, seems that it might be a more appropriate name.

*go-oo.org contact email is kendy at novell.com and here is an extract from the main page

Go-oo has built in OpenXML import filters and it will import your Microsoft Works files. Compared with up-stream OO.o, it has better Microsoft binary file support (with eg. fields support)

Back to LibreOffice and it's goals, this message seems to read like a manifesto:
    http://listarchives.documentfoundation.org/www/discuss/msg03870.html
I can find no repeat of these goals as a list of objectives on documentfoundation.org
Is Italo solely responsible for setting goals for tdf, probably not. Was he shooting from the hip in an attempt to curtail a monster thread ... possibly.

The difficulties with what choices to make regarding writing ooxml output are highlighted in this message:
     http://listarchives.documentfoundation.org/www/discuss/msg03880.html
and I repeat an extract below:

"It leaves Libre Office with three choices when it comes to these
formats. It can either:-

1. Write in the format as used by Microsoft.
2. Write in the format as specified in the ISO standard.
3. Refuse to write in the new formats at all."

The above are exactly that - choices. To just say "want docx" without being aware of the choices involved, is something you might excuse a child of doing.
However adult computer users cannot sidestep responsibility for those choices.

Having written on a pretty dry subject I include a funny (or despairing?) extract from slashdot:

Fool me 48 times, shame on you, fool me the 49th... Shit! You did it again!

But you won't fool me 50 times. I'm sure you wouldn't do that.

Debian Squeeze printing and Samsung Laser (Splix)

When using Samsung ML-2510 with Cups and other printing systems for Linux, you will need to have the splix drivers installed.

These Splix drivers are in the repositories, and are separate to regular cups packages for the following reason:

Cheap and cheerful Lasers like Samsung ML-2510 do not use standard printer languages such as Postscript or PCL. Why Samsung have to be different is beyond me, but in any case, the solution is to install splix.

apt://splix

[ Above apt:// will take you directly to the package if you are using mozilla browser and have aptlinex (Debian) or apturl (Ubuntu) installed ]

( If you are a Mac user and find that your operating system has left you without a suitable driver after your OSX upgrade, then feel free to download the splix source or Debian .tar.gz both of which are licensed under GPL. It would be appreciated if you might remember in the future that GPL software, exists on your system, and helped your system, where your vender support proved insufficient. Enough GPL bashing please. )


Debian light desktop and ML-2510 plus 'Print to File':

On my debian desktop I prefer a light window manager (Xfce) and so I will be exploring how to setup printing without pulling in Gnome/KDE stuff where possible.

I already have xfprint4 installed but this is a frontend is not in itself enough to print, without some sort of backend/daemon such as cups.

apt-get install task-print-server splix

Now task-print-server has pulled in cups, and so a printer daemon/backend is now installed on the system.

( Older Debian systems had a package called printconf
that may have been used instead of task-print-server )

There is a further step now because this Samsung needs more than a standard cups driver - as Samsung Lasers uses Spl2 proprietary printing language.

What you are aiming for is this:

...which indicates that cups have a usable .ppd file for Samsung ML-2510.

To get to that result, you are going to have to interact with cups a little (see below) or you might try just a straight file copy should you feel adventurous.

...and choose your options...

...and setup is pretty much complete.

You might wish to have your system capable of a .pdf output directly from the printing system ( not to be confused with Mozilla browser 'print to file/pdf' )

apt-get install cups-pdf

Something to remember, is to set 'Server Default' properly, if you have several output choices on your system. That way your system knows which is your preference.

The key piece in the above screenshot is the text Server Default)

Additional information about Mozilla browser 'Print to file/pdf':

Mozilla Browser (Firefox) has it's own way of outputting .ps or .pdf files that is independent of your printer server.

( Mozilla relies on libcairo2 vector graphic library for it's 'Print to file/pdf' )

Here is a screenshot that might be familiar to anyone who uses 'Print to file/pdf' or 'Print to file/ps' from Mozilla Firefox.

To clarify further, that 'Output format' radio button choice (PDF or Postscript) is very specific to Mozilla Firefox and is not system wide.

The above crop shows a dialog portion which you will only encounter in Mozilla Firefox, and so do not expect to see that in OpenOffice or elsewhere.

OpenOffice has its own 'Export to PDF' option should you wish to go that way.


Notes and Further Reading:

I have used Mozilla Firefox and Iceweasel (Debian) interchangeably in this article as the actual package name is not an important part of this article.

Splix V 2.0.0 drivers are in Debian 7 (wheezy) and earlier release (squeeze)

• List of Printers (Dell, Samsung, Xerox) that use SPL language [ splix.ap2c.org ]
• Configuration Screenshot for Energy Settings [ splix.ap2c.org ] 
• Using devices that take advantage of JBIG compression and Corporate Setting

The Samsung ML 2510 which I own, does not require a module that supports JBIG compression, however some of the other Samsung SPL2 printer language printers do.

There is much to read about JBIG and JBIG2 if that interests you. Some points:

• All patents have now expired for JBIG (JBIG1)
• JBIG compression system includes no active patents now
      [ wikipedia.org ]
• JBIG2 is very different to JBIG1 and does have active patent filings.
• Pdf standard 1.4 may include data compressed with JBIG2
• JBIG kit download [ cl.cam.ac.uk ]

Many software packages are capable if producing output to the Pdf 1.3 standard, that is one way to avoid the possibility of requiring the receiver having a Pdf reader that needs JBIG2 decompression support.