Open System Services Management and Operations Guide (G06.30+, H06.08+, J06.03+)

In a UNIX environment, these three files are usually associated with the user’s terminal: standard
input is read from the terminal keyboard, standard output is sent to the terminal display, and
standard error is an output logging mechanism that is usually also written to the terminal display.
Data read or written through these files can be redirected using shell redirection specifications to
other processes or to regular (disk) files. On a UNIX system, the pseudo-TTY feature ptty can be
used as a source or sink for such data redirection; although the OSS environment does not have
a pseudo-TTY feature, OSSTTY can do similar data redirection.
A Guardian process has three standard files, comparable to the OSS files mentioned above, that
normally possess the structure of an EDIT file:
• STDIN, usually called the IN file in commands entered from a TACL prompt
• STDOUT, usually called the OUT file in commands entered from a TACL prompt
• STDERR, usually called the TERM file in commands entered from a TACL prompt
By default, these files are associated with the user’s home terminal (HOMETERM). However, the
command that runs a Guardian process can redirect those files to Guardian processes or files.
An OSS user normally launches an OSS shell by logging in through Telserv, most commonly by
starting a TACL session and entering the OSH command. That access method leaves the OSS
standard files associated with the user’s terminal but allows no way for those files to be redirected
to Guardian processes or files.
The OSSTTY utility, described in “OSSTTY” (page 395), removes that restriction. To an OSS process,
OSSTTY appears to be a set of three terminal devices (one for each OSS standard file); to a
Guardian process or the Guardian file system, the OSS process appears to be a Guardian file-system
object. OSSTTY can be started by an individual user through the OSH command or directly by an
OSS administrator.
OSSTTY can be used to redirect one or more OSS standard files to Guardian EDIT files or Guardian
processes. Figure 19 (page 196) illustrates use of the OSS shell when only the OSS standard output
and standard error files are redirected, but input is still accepted from the Telserv terminal that
enters the following command; the process name $ZAAA is assigned by the NonStop operating
system when OSSTTY is started:
OSH -osstty / OUT $DATA.OSSLOG.EDITFIL, TERM $VHS /
Figure 19 Redirecting Selected OSS Standard Files
196 Managing OSS Files