cups - a standards-based, open source printing system
CUPS is the software you use to print from applications like word
processors, email readers, photo editors, and web browsers. It converts the
page descriptions produced by your application (put a paragraph here, draw a
line there, and so forth) into something your printer can understand and then
sends the information to the printer for printing.
Now, since every printer manufacturer does things differently, printing can be
very complicated.
CUPS does its best to hide this from you and your
application so that you can concentrate on printing and less on how to print.
Generally, the only time you need to know anything about your printer is when
you use it for the first time, and even then
CUPS can often figure
things out on its own.
The first time you print to a printer,
CUPS creates a queue to keep track
of the current status of the printer (everything OK, out of paper, etc.) and
any pages you have printed. Most of the time the queue points to a printer
connected directly to your computer via a USB port, however it can also point
to a printer on your network, a printer on the Internet, or multiple printers
depending on the configuration. Regardless of where the queue points, it will
look like any other printer to you and your applications.
Every time you print something,
CUPS creates a job which contains the
queue you are sending the print to, the name of the document you are printing,
and the page descriptions. Job are numbered (queue-1, queue-2, and so forth)
so you can monitor the job as it is printed or cancel it if you see a mistake.
When
CUPS gets a job for printing, it determines the best programs
(filters, printer drivers, port monitors, and backends) to convert the pages
into a printable format and then runs them to actually print the job.
When the print job is completely printed,
CUPS removes the job from the
queue and moves on to any other jobs you have submitted. You can also be
notified when the job is finished, or if there are any errors during printing,
in several different ways.
The easiest way to start is by using the web interface to configure your
printer. Go to "http://localhost:631" and choose the Administration
tab at the top of the page. Click/press on the Add Printer button and follow
the prompts.
When you are asked for a username and password, enter your login username and
password or the "root" username and password.
After the printer is added you will be asked to set the default printer options
(paper size, output mode, etc.) for the printer. Make any changes as needed
and then click/press on the Set Default Options button to save them. Some
printers also support auto-configuration - click/press on the Query Printer
for Default Options button to update the options automatically.
Once you have added the printer, you can print to it from any application. You
can also choose Print Test Page from the maintenance menu to print a simple
test page and verify that everything is working properly.
You can also use the
lpadmin(8) and
lpinfo(8) commands to add
printers to
CUPS. Additionally, your operating system may include
graphical user interfaces or automatically create printer queues when you
connect a printer to your computer.
The
OpenPrinting CUPS web site (
https://openprinting.github.io/cups)
provides access to the
cups and
cups-devel mailing lists,
additional documentation and resources, and a bug report database. Most
vendors also provide online discussion forums to ask printing questions for
your operating system of choice.
CUPS commands use the following environment variables to override the
default locations of files and so forth. For security reasons, these
environment variables are ignored for setuid programs:
- CUPS_ANYROOT
- Whether to allow any X.509 certificate root (Y or N).
- CUPS_CACHEDIR
- The directory where semi-persistent cache files can be
found.
- CUPS_DATADIR
- The directory where data files can be found.
- CUPS_ENCRYPTION
- The default level of encryption (Always, IfRequested,
Never, Required).
- CUPS_EXPIREDCERTS
- Whether to allow expired X.509 certificates (Y or N).
- CUPS_GSSSERVICENAME
- The Kerberos service name used for authentication.
- CUPS_SERVER
- The hostname/IP address and port number of the CUPS
scheduler (hostname:port or ipaddress:port).
- CUPS_SERVERBIN
- The directory where server helper programs, filters,
backend, etc. can be found.
- CUPS_SERVERROOT
- The root directory of the server.
- CUPS_STATEDIR
- The directory where state files can be found.
- CUPS_USER
- Specifies the name of the user for print requests.
- HOME
- Specifies the home directory of the current user.
- IPP_PORT
- Specifies the default port number for IPP requests.
- LOCALEDIR
- Specifies the location of localization files.
- LPDEST
- Specifies the default print queue (System V standard).
- PRINTER
- Specifies the default print queue (Berkeley standard).
- TMPDIR
- Specifies the location of temporary files.
~/.cups/client.conf
~/.cups/lpoptions
CUPS conforms to the Internet Printing Protocol version 2.1 and
implements the Berkeley and System V UNIX print commands.
CUPS printer drivers, backends, and PPD files are deprecated and will no longer
be supported in a future feature release of CUPS. Printers that do not support
IPP can be supported using applications such as
ippeveprinter(1).
cancel(1),
client.conf(5),
cupsctl(8),
cupsd(8),
lp(1),
lpadmin(8),
lpinfo(8),
lpoptions(1),
lpr(1),
lprm(1),
lpq(1),
lpstat(1), CUPS Online
Help (http://localhost:631/help), OpenPrinting CUPS Web Site
(
https://openprinting.github.io/cups), PWG Internet Printing Protocol
Workgroup (
http://www.pwg.org/ipp)
Copyright © 2021-2022 by OpenPrinting.