Open System Services Programmer's Guide

7 Managing I/O
This section describes how to manage OSS tape, terminal, and printer I/O. It discusses the following
topics:
ContentTopic
Summary of the differences between OSS and UNIX I/O.“Common and Unique Characteristics” (page 207)
The objects on which you can use OSS I/O functions and
Guardian procedures.
“I/O Interoperability” (page 207)
Tape I/O using pax and the Guardian API.“Tape I/O” (page 208)
Terminal I/O using the OSS API.“Terminal I/O” (page 210)
Using the OSSTTY facility to redirect the OSS standard files
to Guardian processes and EDIT files.
“Using OSSTTY to Redirect Input and Output to Guardian
Objects” (page 214)
Printing OSS files using the OSS and Guardian APIs.“Printer I/O” (page 226)
List of each OSS I/O function with notes about its OSS
implementation and its use on Guardian objects.
“OSS I/O Management Functions” (page 233)
List of each Guardian I/O procedure with notes about its
use on OSS objects.
“Guardian I/O Management Procedures” (page 234)
The major difference between managing I/O with the OSS API and managing I/O with the UNIX
operating system is that the OSS environment offers limited I/O features. For greater control over
most I/O operations, you must use Guardian procedures.
Common and Unique Characteristics
OSS tape I/O and printing are handled by OSS utilities. There are no direct OSS programmatic
tape and printer interfaces. For programmatic control, you must use the Guardian API.
Features Common to UNIX and OSS Terminal I/O Management
OSS terminal I/O is handled as with UNIX network terminals. As in UNIX systems, the name of
the controlling terminal is /dev/tty. Both canonical and noncanonical input are supported.
Features Unique to OSS Terminal I/O Management
Some terminal parameter values have no effect, because all access to the OSS environment is
through the Telserv server and a VT100 terminal emulation or through OSSTTY. The OSS environment
supports two types of windows: static windows, which are opened with the Subsystem Control
Facility (SCF), and dynamic windows, which Telserv or OSSTTY creates when it receives a
connection request.
I/O Interoperability
OSS terminal I/O functions operate only on the terminal device /dev/tty. The functions
cfsetispeed() and cfsetospeed() have no effect on the network terminals (they affect only
local terminals). The function tcsetattr affects both the Telserv and OSSTTY terminals.
There are no OSS I/O functions that apply to printers or tape drives.
Guardian I/O procedures operate only on Guardian devices.
Common and Unique Characteristics 207