Dissecting and debugging the cups printing system – debian wiki database administrator job description _ data recovery
The aim in this article and the sections of the wiki linked from it is to give some insight on printing with CUPS in Debian 8 (Jessie). Database diagram tool Database d b Differences between Debian 7 (Wheezy) and Debian 8 may be alluded to without necessarily going into much detail. Database field types P d database The testing methods are applicable in Wheezy 7 and the two distributions are broadly similar regarding the filtering systems.It is hoped that there will be sufficient detail to give an understanding of how parts of CUPS and the filtering system work and co-operate and to enable effective troubleshooting.
CUPS (a product of Apple Inc.) may be viewed as the manager of all printing processes via its scheduler, cupsd. Data recovery best buy Database engineer It also provides a number of filters which prepare a print job for presentation to a printer. Raid 5 data recovery Database entity However, some filters were not required by Apple so they were generously donated to the Linux Foundation and now form the basis for the cups-filters and cups-filters-core-drivers packages in Debian 8.
One purpose of the last paragraph is to afford a glimpse into the complexity of the relationships between the components of the printing system.
Database administrator salary nyc Database engineer salary When the contributions of developers of free software such as Ghostscript, Poppler, Gutenprint, Hewlitt-Packard etc and hardware manufacturers are thrown into the mix we may marvel that the whole thing works so effectively.
Throughout this account CUPS is used to refer to what you get if the source is downloaded from cups.org and compiled. Database p Database error cups-filters is a Linux Foundation project which interworks with CUPS but responsibility for its maintainence lies with the Linux Foundation and openprinting, not CUPS.
Prior to Wheezy the filtering system was devised to process PostScript files; that is, any file recognised by CUPS as a known mime type was first converted to PostScript before being processed. Cloud 9 database Database engine tuning advisor At present we have a system which is designed to process files in PDF format; known mime types are first converted to a PDF if necessary.
“PDF in” is relatively easy to accomplish; we simply get applications to generate and send PDF, which is what Iceweasel and Evince (amongst other applications) do by default. Data recovery on ssd Database erd But not all applications do generate PDF and users still want to print text, image and PostScript files. Database query tools Database etl Also, the printer may not understand PDF but requires PostScript, PCL or some proprietary language. Database 2000 Database er diagram A generalised filtering chain would be
There is one important situation in which cups-filters departs from the PDF workflow. Database business rules Database entry That is when the input file is PostScript and the file is being sent to a PostScript printer. Iphone 5 data recovery Database field We should have
but. Database implementation Database foreign key although this generally works, it can introduce buggy behaviour such as delays and font problems because of the pstopdf and pdftops conversions. Raid 1 data recovery software Database fundamentals After a discussion the filter chain for PostScript job sent to a queue which feeds a PostScript printer now uses pstops.
pstops is a CUPS filter and is part of the older PostScript-centric workflow. Seagate data recovery Database first entity framework A second situation where the PDF printing workflow is departed from occurs for PostScript from the Adobe Reader. Database report Database file Details are in /usr/share/cups/mime/cupsfilters.convs.
Since CUPS 2.1.0 the PPD files of the local print queues in /etc/cups/ppd/ are not world-readable as the default permissions of the ConfigFilePerm option in /etc/cups/cups-files are applied. Data recovery specialist Database functions A consequence is that the pstopdf shell script cannot read the PPD file of a print queue directly from the /etc/cups/ppd/ directory, so cups-filters 1.10.0 integrated the functionality of pstopdf into the gstoraster filter with the wrapper filter gstopdf. Data recovery iphone 6 Database for dummies Post-1.10.0 the filter chain is
It goes without saying that root can do anything: install a print queue, edit files in /etc/cups, read log files in /var/cups/log, manipulate files produced by the filtering subsystem and start and stop cupsd. Database building Database form A user who is a member of the lpadmin group can install a print queue but is not able to do much else.
However, some printing-related commands which live in /usr/sbin are available to a user. Data recovery top 10 Database field definition This means that quite a bit of debugging can be done without having root privileges – which is better than nothing. Database hosting Database field types These commands will be referenced by giving the full path to the command.
For debugging the primary tool is the error log, /var/log/cups/error_log. Data recovery best Database google Diagnosing printing problems is not always easy but without the error log it can make progress to a solution difficult. Data recovery program Database gui Don’t forget that not everything which is in the error_log is the responsibilty of CUPS. 7 data recovery 94fbr Database gif Errors in the filtering chain are also logged there and could be the responsibilty of other programs such as cups-filters, Ghostscript, Poppler, colord etc, all non-CUPS software. Database languages Database generator In essence, CUPS has the task of spooling and scheduling print jobs and uses the error_log to make a record of this.
Also bear in mind the error_log may shed little light on some problems and other techniques and approaches may need to be employed. Database ranking Database graphic There could be misconfigurations in CUPS’ files, the printer or a PPD file; the input file from an application might be defective in some way; the filter chain might be suboptimal for the job.
The file /etc/cups/cupsd.conf can also be edited by replacing “LogLevel warn” with “LogLevel debug” or (for masochists) “LogLevel debug2”. Data recovery youtube Database graph cupsd will need a manual restart if this is done:
For reasons we will not go into here the error_log may have many lines saying “cupsd is not idle any more, canceling shutdown.” If you find them distracting the following command will remove them:
It is not possible to give a complete account of what to look for in an error_log because the job and the setup in the CUPS configuration files cupsd.conf and cups-files will affect its contents. 911 database Database glossary The presence of “error” and “failed” should ring alarm bells but tracking down the cause may not be as easy as one would like. Data recovery download Database gale Handy search terms are “Auto-typing” and “filter”. Data recovery after factory reset Database google drive Both outcomes should conform with your expectations of how a job should be processed. Database schema design Database google docs A glance at “argv” is always worth it to see what options are being sent to CUPS.
it stays there and does not enter the filtering subsystem. Database uml G info database Such a file can be identified from its date-stamp and because its name will begin with a “d”.
The file type can identified with file and should be capable of being viewed to see what the application has sent. Data recovery ntfs G info database search It can also be processed with cupsfilter.
Any print job can be printed to a file. Database error Database hosting As root, have “FileDevice Yes” in /etc/cups/cups-files.conf. Database functions Database hacking As root or a member of the lpadmin group set up a print queue which prints to a file rather than sending to a printer. Top 10 data recovery Database history Either
What can be done with this printer-ready file? One possibility is that it might be capable of being viewed. Database job titles Database hierarchy If it looks fine the reason for a bad result on paper could lie with the backend used to send it to the printer or the way the printer interprets the file.
If the file cannot be viewed you could examine the previous stages which lead to its production and see whether they give acceptable outputs. Data recovery linux live cd Database host name If they do you might begin to think in terms of three causes for the problem:
Once the filtering system has produced a printer-ready file it is sent to the printer by a backend driver, which is really just another filter. S pombe database Database hardening The backend driver chosen is determined by the DEVICE_URI used when the print queue was deployed. Database usa Database health check For example,
Suppose you have a printer-ready file produced via the filtering system using cupsfilter or which has been captured before being sent to the printer. Data recovery pro license key Database hardware The command
will avoid the filtering system and use only a backend filter before the file is passed to the printer. Data recovery on android Database high availability A record of the transaction will be in the error_log.
It can sometimes happen that a file sent to a PostScript printer fails in some way. Icare data recovery 94fbr Database help For example, an error message might be produced on the first page and subsequent pages are blank. Image database H2 database The cause is thought to lie with buggy behaviour in the printer’s PostScript interpreter even when given valid PostScript.
The pdftops filter has the option to convert the PDF into PostScript using Ghostscript, Poppler, Cairo or Adobe Reader. Database web application H2 database tutorial The default mode is one which uses Poppler when the printer make is Brother, Minolta or Konica Minolta but Ghostscript for other printer models. Database graphic H2 database viewer If there is a problem with one of these other models it may be beneficial to switch to rendering PostScript from the PDF with the “pdftops-renderer” option. In databases a category of data is called a H2 database console Details are in /usr/share/doc/cups-filters/README.txt.gz.
A USB problem can be difficult to track down. Database wordpress H2 database client The USB backend uses libusb and there is the possibility of a bug in that software. Note 2 data recovery H2 database url Also, USB to parallel adapters do not always give trouble-free operation. Tally erp 9 data recovery H2 database file However, it is not entirely unknown for printers to have bugs in their implementation of the USB standard and, indeed, CUPS has “quirks” rules to deal with such issues. Database erd H2 database download Adding a vendor or printer to the database can involve submitting information upstream. Database google docs Database index Here is an account and analysis of a printing problem solved by the application of a USB quirk.
In CUPS 1.5.x the IPP backend was rewritten to make it conform more rigorously to IPP standards. Database 5500 Database image Unfortunately, it is not unknown for IPP implementations on some printers and print servers to be buggy and the change resulted in some of them failing to print.
A solution is to revert to using the less stringent IPP backend from CUPS 1.4.x for the DEVICE_URI of a print queue. Data recovery kit Database instance It is provided as ipp14.
Discovery of mDNS (Bonjour) shared printers takes place by default when avahi-daemon is installed. Database meaning Database integrity Applications using the GTK dialog subsystem will see these printers in their dialogs. Gale database Database in recovery Adding cups-browsed to the system allows other applications and the command line programs also to know about these Bonjour advertised print queues and printers.
It is possible for all the queue filters to operate correctly and for the backend to behave impeccably but nothing gets printed. Data recovery pc Database in excel One cause is a firewall misconfiguration. Data recovery easeus Database isolation levels Check with
and look at the avahi-browse -art output. Top 10 data recovery software Database implementation Failed to resolve service and an address line which is not in the form xxx.xxx.xxx.xxx would be indications of such a misconfiguration.
A failure to get the print job to a remote printer might also be a router problem or bugs in avahi-daemon. Database oracle Database is in transition The first could necessitate powering the router off and on; resolving the second is beyond the scope of this wiki page.
The Debian printing system based on CUPS has matured over the years and generally operates reliably with a great number of printers. Data recovery services reviews Database jobs However, in what is still a developing environment, bugs are to be expected and some of them may visibly affect the printing process.
A user’s reaction to an inability to print can vary from viewing it as merely annoying up to intolerable. Database 12c new features Database join In spite of the inconvenience it is rarely the case that a failure to produce a satisfactory printout deserves setting the severity level on a bug report to anything greater than “important”, which is described as
The usual program employed to report a bug is reportbug, which will guide you through the process. Database lyrics Database journal In addition to describing your problem there are other data which are useful to give a complete picture of your issue. Database 360 Database jokes The printer vendor and model and how it is connected (USB, parallel, socket etc) to the machine are often relevant details. Database architect salary Database job titles Try
for the make and model. Database administrator job description Database join types Very useful detail can also be obtained from an error_log showing what happens when printing takes place. Data recovery app Database java Compressing a lengthy log with gzip or xz is an option to consider taking.
With the large number of packages involved in the printing system it can be perplexing to decide which one a bug applies to. R database connection Database job description If the report is sent to the cups package there is no harm done.