postio - serial interface for PostScript printers
postio -l line [-D] [-i] [-q] [-t] [-S] [-b speed] [-B num]
[-L file] [-P string] [-R num] [file...]
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
-D Enable debug mode. Guarantees that everything read on
line will be added to the log file (standard error by
-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
Transmit data over line at baud rate speed. Recognized
baud rates are 1200, 2400, 4800, 9600, and 19200. The
default speed is 9600 baud.
Set the internal buffer size for reading and writing
files to num bytes. By default num is 2048 bytes.
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.
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
Send string to the printer before any of the input
files. The default string is simple PostScript code
that disables timeouts.
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 return-
ing 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 con-
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 accom-
plish 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 mechan-
ism, so -q is disabled and the program runs as a single pro-
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 occa-
sional ^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
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
example% postio -t -l /dev/tty22 -L log program >results
The following exit values are returned:
0 Successful completion.
An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWpsf |
download(1), dpost(1), postdaisy(1), postdmd(1), postmd(1),
postprint(1), postreverse(1), posttek(1), attributes(5)
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 con-
nect 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 con-
nected to RADIAN. The -S option is not generally recom-
mended and should be used only if all other attempts to
establish a reliable connection fail.
Man(1) output converted with