postio(1) (Line Printer Spooling Utilities) postio(1)
NAME
postio - serial interface for PostScript printers
SYNOPSIS
postio -l line [options] [files]
DESCRIPTION
postio sends files to the PostScript printer attached to line. If no
files are specified the standard input is sent. The first group of
options should be sufficient for most applications:
-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.
-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 doesn't begin with a / it may be
treated as a Datakit destination.
-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 num Set the internal buffer size for reading and writing files
to num bytes. By default num is 2048 bytes.
-D Enable debug mode. Guarantees that everything read on line
will be added to the log file (standard error by default).
-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.
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postio(1) (Line Printer Spooling Utilities) postio(1)
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
Run as a single process at 9600 baud and send file1 and file2 to the
printer attached to /dev/tty01:
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postio(1) (Line Printer Spooling Utilities) postio(1)
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:
postio -R2 -B4096 -l/dev/tty01 -Llog file1 file2
Establish an interactive connection with the printer at Datakit
destination my/printer:
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:
postio -t -l /dev/tty22 -L log program >results
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. For example, the code needed
to connect to a Datakit destination may work only on System V and may
require that the DKHOST software package be available at compile
time.
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.
DIAGNOSTICS
An exit status of 0 is returned if the files ran successfully.
System errors (such as an inability to open the line) set the low
order bit in the exit status, while PostScript errors set bit 1. An
exit status of 2 usually means the printer detected a PostScript
error in the input files.
SEE ALSO
download(1), dpost(1), postdaisy(1), postdmd(1), postmd(1),
postprint(1),
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postio(1) (Line Printer Spooling Utilities) postio(1)
postreverse(1), posttek(1).
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