Managing Users and Printers on the server cups.cs

This document is addressed to those who are responsible for adding users to the PYKOTA print accounting system albeit you may want to refer to CupsCsServer if you encounter problems. Furthermore, all of this was done on Ubuntu based Linux systems.

Introduction

The hostname cups.cs is a CNAME. You can login to the host using your core.cs regional UNIX password.

You must login from cscfnet, otherwise, you will be denied access. Check the file /etc/hosts.allow for the current access configuration.

Pykota and Cups

The host cups.cs has CUPS (Common Unix Printing System) and Pykota installed on it. The Pykota system is a print accounting system with many features.

Anyone in the Unix pykota group can run Pykota commands. To check whether you are in the groups type groups useruserid. You should see pykota listed. If this is not the case. Please have a system administrator add you to the group (not currently managed by our accounting system).

Note about userids

For both Macs and Windows it may be necessary to make the userid of the current login match their UWuserid. Both OSes tend to silently transmit that information when connecting to a printer. Since all of our quotas are controlled by the UWuserid it will generally only work if they match. For notes on changing the Mac userid, see: ChangeMacShortName

Adding a user to the Users Database

Adding a user to the users database does not mean that user will be able to print but merely makes it possible to add them to a Pykota managed print queue.

If the user xyz does not exist in the database, then

      pkusers --list xyz

yields

      pkusers --list xyz
      /usr/bin/pkusers : There's no user matching xyz

whereas if the user exists in the database one gets something like

     xyz - <xyz@uwaterloo.ca>
         Limited by : quota
         Account balance : 0.00
         Total paid so far : 0.00
         Overcharging factor : 1.00

To add the user xyz to the users database run

     pkusers --add xyz

Adding and deleting users from a print queue

Determine whether a user has been added to a print queue

To see whether a user xyz (remember just because a user is in the database does not mean they have been added to any print queues!) belongs to a print queue ABC run

     edpykota --list --printer ABC xyz

It is required that the user has been added to the Pykota database as described above. Remember this does NOT mean they can print!

Adding a user to a print queue

Given a user xyz that exists in the users database and a print queue ABC that exists in the print queue database we want to add the user xyz to ABC. We accomplish this by running

     edpykota --add --printer ABC xyz

The default behaviour of this command is to allow the user to print as many pages as they want as often as they want. Accounting on how much they print will be done. It is possible to change this behaviour in subtle ways that will describe as the need arises later in this document.

Remove a user from a print queue

To delete the user xyz from print queue ABC run

     edpykota --delete --printer ABC xyz

Check for conflict with CUPS "Set Allowed Users"

CUPS has a native (not part of pykota) facility to allow or deny a list of users. For each printer listed by http://cups.cs:631/printers/ , there is a button labelled "Set Allowed Users". If there are any users in the allow or deny lists, anyone attempting to use the printer must first pass this hurdle before pykota is asked whether they can print. This is easy to miss and sure to cause confusion. So, make sure the "Set Allowed Users" list is empty when using a printer with pykota.

Displaying a user's quotas

The command repykota is quite useful for this purpose. Typing it without any options and piping it through less is instructive, that is, type repykota|less. Some examples usages are given by: repykota --printer lp will print the quota status for all users who use the lp printer and repykota --printer "laser*,*pson" jerome "jo*" will print the quota status for user jerome and all users whose name begins with "jo" on all printers which name begins with "laser" or ends with "pson".

Refined manipulation of user's quotas per print queue

Suppose user xyz is in the user database (see above for definition) and assume we have added them to a print queue ABC (see above for how to do this). Suppose instead of allowing unlimited printing we want to limit them to a fixed number of pages, say an upper bound of 550 pages (not to be exceeded, also known as a hard limit) and and a lower limit of 500 (can be exceeded a bit, known as a soft limit) pages. Then we do

     edpykota --printer ABC  -S 500 -H 550 xyz

If we run repykota --printer ABC xyz we should see

repykota --printer ABC xyz
Report for user quota on printer ABC ()
Pages grace time: 7 days
Price per job: 0.000
Price per page: 0.000
User           overcharge   used    soft    hard    balance grace         total       paid warn
-----------------------------------------------------------------------------------------------
xyz          -Q   1.0       7     500     550       0.00                   7       0.00    0
                                                              Total :         7       0.00
                                                               Real :       753

Notice that we could charge a price if we wanted to. Ultimately the man page of the command edpykota is authoritative. Having said that, we hope to provide instructive examples in this wiki that will cover all cases as they come up.
If one wanted to set the Soft and Hard limits for all users on a particular printer use:

     edpykota --printer ABC  -S 500 -H 550

This will not zero everyone's current print count, just set their limits.

Adding a Print Queue to Pykota

We assume that a system administrator has Pykota enabled the print queue, see CupsCsServer#A_necessary_pre_condition_for_PY for the details if the commands below do now work.

The command pkprinters is used to add and delete pre-existing CUPS print queues to Pykota's database. It has a command line syntax that is very similar to that of pkusers, in particular we can find out whether ABC exists by running

     pkprinters --list ABC

If Pykota claims to be not aware of the print queue, you can add to Pykota by by running

     pkprinters --add ABC

It is highly likely that a UNIX system administrator will have already done this step but for reference sake we include a note here, see CupsCsServer#A_necessary_pre_condition_for_PY for an important caveat if you encounter difficulties with the command below.

External References

• Cups Homepage
• http://cups.cs/doc/pykota/html for official docs on pykota.