Telserv Manual

Subsystem Control Facility (SCF) for Telserv

Telserv Manual—427174-009

4-6

Modes of Operation

SCF can be run in two modes: interactive or noninteractive. Because interactive and

noninteractive input are treated differently by SCF, the following distinctions are

important:



The mode is interactive when both input and output pass through the same

terminal, or when the same process is used for both input and output. For instance,

using the OUT command or using the / OUT file-spec / parameter within a

command causes SCF to run in noninteractive mode. This rule affects the use of

abbreviations when you enter keywords: abbreviations (formed by truncating

keywords, provided the result is unambiguous) are permitted in interactive mode

only. For example, in interactive mode you can abbreviate the VERSION command

to VE, but in a command file (noninteractive mode) you must spell out VERSION.



Interactive input from a terminal is characterized by the entry of a command

followed by a carriage return. When a process is used for both input and output,

SCF waits for the process to send a request and treats the process in the same

manner as a terminal.



Noninteractive input usually appears in the form of a command (Obey) file.

Command (Obey) files are usually EDIT files that contain a series of commands.

For more information about interactive and noninteractive modes, see the Subsystem

Control Facility (SCF) Reference Manual.

Setting the Initial Input Source

To specify an initial input source for an SCF session, use the IN option of the RUN

command. You can specify a terminal (identified by its logical-device name) or a disk

file. For example, the following TACL RUN command initiates SCF and directs it to

read commands from a disk file named $DATA.SCF.STARTUP (if not specified, the

system name and volume name are the default names currently in use by the TACL

command interpreter through which the RUN command was entered):

19> SCF / IN $DATA.SCF.STARTUP /

If you run SCF from the TACL command interpreter without specifying an input file,

SCF assumes that the input is coming from your terminal.

Output Destinations

SCF can direct output to a disk file, an application process, a terminal, or a printer. The

initial output destination is determined by the form of the RUN command used to

initiate SCF. The output destination can be changed dynamically during an SCF

session.