Specifications

4-34
Guide to Printers and Printing
Understanding Backend Routines in libqb
This article defines the set of library routines that the backend should use to communicate
with the qdaemon process. These routines are in the /usr/lib/libqb.a library; they were
designed to make the task of writing a backend as easy as possible. These backend
routines are available using the ld or cc command–line option –lqb.
For information on using these routines with the backend, see Understanding the Interaction
between qdaemon and the Backend on page 4-29.
get_align() Returns TRUE or FALSE, telling whether an alignment
form–feed is to be printed. A form–feed is printed only
when the printer has been idle and is about to print a new
job. The form–feed aligns the paper to top–of–form and is
helpful if someone moved the paper while the printer was
idle.
get_cmd_line() Returns a pointer to an array of characters containing the
enq command line as invoked by the user. The string
returned does not contain the name /usr/bin/enq, any of
the file names specified, or any options that were sent to
the backend using the enq –o option. For example, if the
user enters the command line enq –Plp0 –Bgn –o
–i15 filename, the get_cmd_line function returns the
string –Plp0 –Bgn. This function is useful when the
backend needs to know the command line options a user
provided when the job was submitted.
get_copies() Returns the number of copies to be printed. Its return value
is of type int.
get_device_name() Returns a pointer to an array of characters containing the
device name.
get_feed() Returns the number of feed pages to be printed. Its return
value is of type unsigned int. Feed pages are blank pages
printed only when the printer has become idle. This makes
it easier to tear off paper from the printer.
get_from() Returns an array of characters containing the name of the
person who made the print request. The return value is of
type char*.
get_header() Returns NEVER, ALWAYS, or GROUP (#include
<IN/backend.h>). Its return value is of type unsigned int. A
header is a page preceding a file that shows its title, date,
its recipient, and other information.
get_job_number() Returns job number of current print. Its return value is of
type int.
get_mail_only() Returns TRUE if the user specifies mail–only.
get_qdate() Returns a string showing the date that the request was
queued. The return value is of type char*.
get_queue_name() Returns an array of characters containing the queue name.
get_title() Returns an array of characters containing the title of the job
being printed. The return value is of type char*.
get_trailer() Returns NEVER, ALWAYS, or GROUP. Its return value is
of type unsigned int. A trailer is a page following a file that
gives the name of the user of the output.