postio(1M) (Line Printer PostScript Utilities) postio(1M)
NAME
postio - serial interface for PostScript printers
SYNOPSIS
/usr/lib/lp/postscript/postio -lline [options] [files]
DESCRIPTION
postio sends files to the PostScript printer attached to line. If no
files are specified, the output is sent to stdin.
OPTIONS
The first group of options should be sufficient for most applications:
-bspeed
Transmits data over line at baud rate speed. Recognized baud
rates are 1200, 2400, 4800, 9600, and 19200. The default speed
is 9600 baud.
-lline Connects 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.
-Bnum Sets the internal buffer size for reading and writing files to
num bytes. By default num is 2048 bytes.
-D Enables debug mode. Guarantees that everything read on line
will be added to the log file (standard error by default).
-Lfile Data received on line gets put in file. The default log file is
standard error. Printer or status messages that don't indicate
a change in state are not normally written to file but can be
forced out using the -D option.
-Pstring
Sends string to the printer before any of the input files. The
default string is simple PostScript code that disables
timeouts.
-Rnum Runs 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 pro-
grams:
-i Runs the program in interactive mode. If files are available,
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postio(1M) (Line Printer PostScript Utilities) postio(1M)
they are sent first and output is then sent to stdin. 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 stdout. 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 Slows down 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 interac-
tive mode.
The best performance will usually be obtained by using a large inter-
nal buffer (the -B option) and by running the program as separate read
and write processes (the -R 2 option). Inability to fork the addi-
tional process causes postio to continue as a single read/write pro-
cess. When one process is used only data sent to the printer is flow
controlled.
The options are not all mutually exclusive. The -i option has priority
over other options, 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 con-
nection 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(1M) (Line Printer PostScript Utilities) postio(1M)
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 desti-
nation 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
WARNINGS
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 UNIX that are
currently supported by the program. For example, the code needed to
connect to a Datakit destination may only work on System V and may
require that the DKHOST software package be available at compile time.
There may be no default line so using -l option is strongly recom-
mended. If omitted postio may attempt to connect to the printer using
standard output. If Datakit is involved the -b may be ineffective and
attempts by postio to flow control 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 only be used if
all else fails to establish a reliable connection.
DIAGNOSTICS
A 0 exit status is returned if the files ran successfully. System
errors (e.g. can't 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
dpost(1M), postdaisy(1M), postdmd(1M), postmd(1M), postprint(1M),
postreverse(1M), posttek(1M).
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