POSTIO(1) User Commands POSTIO(1)

NAME

postio - serial interface for PostScript printers

SYNOPSIS

postio -l line [-D] [-i] [-q] [-t] [-S] [-b speed] [-B num]
[-L file] [-P string] [-R num] [file]...


/usr/lib/lp/postscript/postio

DESCRIPTION

postio sends files to the PostScript printer attached to line. If no
files are specified the standard input is sent.

OPTIONS

The first group of options should be sufficient for most
applications:

-D
Enable debug mode. Guarantees that everything read on
line will be added to the log file (standard error by
default).


-q
Prevents status queries while files are being sent to
the printer. When status queries are disabled a dummy
message is appended to the log file before each block is
transmitted.


-b speed
Transmit data over line at baud rate speed. Recognized
baud rates are 1200, 2400, 4800, 9600, and 19200. The
default speed is 9600 baud.


-B num
Set the internal buffer size for reading and writing
files to num bytes. By default num is 2048 bytes.


-l line
Connect to the printer attached to line. In most cases
there is no default and postio must be able to read and
write line. If the line does not begin with a / it may
be treated as a Datakit destination.


-L file
Data received on line gets put in file. The default log
file is standard error. Printer or status messages that
don't show a change in state are not normally written to
file but can be forced out using the -D option.


-P string
Send string to the printer before any of the input
files. The default string is simple PostScript code that
disables timeouts.


-R num
Run postio as a single process if num is 1 or as
separate read and write processes if num is 2. By
default postio runs as a single process.


The next two options are provided for users who expect to run postio
on their own. Neither is suitable for use in spooler interface
programs:

-i
Run the program in interactive mode. Any files are sent first
and followed by the standard input. Forces separate read and
write processes and overrides many other options. To exit
interactive mode use your interrupt or quit character. To get a
friendly interactive connection with the printer type executive
on a line by itself.


-t
Data received on line and not recognized as printer or status
information is written to the standard output. Forces separate
read and write processes. Convenient if you have a PostScript
program that will be returning useful data to the host.


The last option is not generally recommended and should only be used
if all else fails to provide a reliable connection:

-S
Slow the transmission of data to the printer. Severely limits
throughput, runs as a single process, disables the -q option,
limits the internal buffer size to 1024 bytes, can use an
excessive amount of CPU time, and does nothing in interactive
mode.


The best performance will usually be obtained by using a large
internal buffer (the -B option) and by running the program as
separate read and write processes (the -R 2 option). Inability to
fork the additional process causes postio to continue as a single
read/write process. When one process is used, only data sent to the
printer is flow controlled.


The options are not all mutually exclusive. The -i option always
wins, selecting its own settings for whatever is needed to run
interactive mode, independent of anything else found on the command
line. Interactive mode runs as separate read and write processes and
few of the other options accomplish anything in the presence of the
-i option. The -t option needs a reliable two way connection to the
printer and therefore tries to force separate read and write
processes. The -S option relies on the status query mechanism, so -q
is disabled and the program runs as a single process.


In most cases postio starts by making a connection to line and then
attempts to force the printer into the IDLE state by sending an
appropriate sequence of ^T (status query), ^C (interrupt), and ^D
(end of job) characters. When the printer goes IDLE, files are
transmitted along with an occasional ^T (unless the -q option was
used). After all the files are sent the program waits until it's
reasonably sure the job is complete. Printer generated error messages
received at any time except while establishing the initial connection
(or when running interactive mode) cause postio to exit with a non-
zero status. In addition to being added to the log file, printer
error messages are also echoed to standard error.

EXAMPLES

Example 1: Examples of the postio command.

Run as a single process at 9600 baud and send file1 and file2 to the
printer attached to /dev/tty01:


example% postio -l /dev/tty01 file1 file2


Same as above except two processes are used, the internal buffer is
set to 4096 bytes, and data returned by the printer gets put in file
log:


example% postio -R 2 -B 4096 -l/dev/tty01 -L log file1 file2


Establish an interactive connection with the printer at Datakit
destination my/printer:


example% postio -i -l my/printer


Send file program to the printer connected to /dev/tty22, recover any
data in file results, and put log messages in file log:


example% postio -t -l /dev/tty22 -L log program >results

EXIT STATUS

The following exit values are returned:

0
Successful completion.


non-zero
An error occurred.

SEE ALSO

download(1), dpost(1), postprint(1), postreverse(1), attributes(7)

NOTES

The input files are handled as a single PostScript job. Sending
several different jobs, each with their own internal end of job mark
(^D) is not guaranteed to work properly. postio may quit before all
the jobs have completed and could be restarted before the last one
finishes.


All the capabilities described above may not be available on every
machine or even across the different versions of the UNIX system that
are currently supported by the program.


There may be no default line, so using the -l option is strongly
recommended. If omitted, postio may attempt to connect to the printer
using the standard output. If Datakit is involved, the -b option may
be ineffective and attempts by postio to impose flow control over
data in both directions may not work. The -q option can help if the
printer is connected to RADIAN. The -S option is not generally
recommended and should be used only if all other attempts to
establish a reliable connection fail.

May 13, 2017 POSTIO(1)