HP 3000 Manuals HP 3000 Manuals
Redirecting Input, Output, and the Schema Listing
By default, command input comes from $STDIN (the user terminal
interactively; the job file in batch mode). By default, output is
directed to $STDLIST (the user terminal interactively or the job's
$STDLIST spool file in batch mode).
You can redirect input, output, and the schema listing by issuing the
following formal file designators either before or during DBChange Plus
operation. (To issue them during DBChange Plus operation, be sure to
enter a colon (:) after the DBCPLUS prompt (>).)
* DBCIN--the formal file designator for command input. If you set a
file equation for DBCIN before running the DBCPLUS program,
commands are read from the named file.
To read input from a file, use the following file equation:
:file dbcin= InFileName
* DBCOUT--the formal file designator for command output. This file
can be a temporary file or a permanent file large enough to hold
the contents of the output. The DBCOUT file equation must be used
with the OUTPUT LP command.
To send output to a new permanent file, use the following file
equation:
:file dbcout= FileName;dev=disc;rec=-80,16,f,ascii;disc= n;save;nocctl
where FileName is the name of the new permanent file, and n is the
approximate number of lines in the output file.
Printing the Schema to an MPE XL File
To print the schema to a new permanent MPE XL file, use the PRINT SCHEMA
command specifying a FileName. The FileName must adhere to the MPE XL
file naming conventions. (Refer to the MPE XL General Users Reference
Manual.) DBChange automatically builds a fixed ASCII disk file which can
accommodate a file size up to 60000 lines. If the file does not use all
the allotted disk space, any unused disk space is returned back to the
system.
CAUTION When redirecting output to a disk file, be sure the file is
large enough to accommodate all output. If the file is not
large enough, the DBCPLUS or DBAPLUS programs can abort causing
the database to be in an inconsistent state.
Printing the Schema to an MPE XL File in Interactive Mode.
When you issue the PRINT SCHEMA FileName command in interactive mode, the
new file is opened and the DBCPLUS program verifies if a file with the
same name already exists. If one does, you are prompted and must confirm
if you want the existing file purged. If a file with the same name does
not exist, the new file is built and the schema is printed to the new
file.
In the following example, the schema for the ORDERS database is
interactively printed to a file named ORDERSZ, which already exists:
>print schema ordersz
Old schema file ORDERSZ exists. Purge and create a new file [y/N]? y
Schema is printed.
>
Printing the Schema to an MPE XL File in Batch Mode.
When you issue the PRINT SCHEMA FileName command in batch mode and a file
with the same name already exists, the new file is not created and the
following message appears in your output:
Duplicate schema file. Cannot process PRINT SCHEMA.
If a file with the same name does not exist, the new file is built and
the schema is printed to the new file.
Refer to PRINT SCHEMA in chapter 10, "DBChange Plus Commands," for a
detailed description of the command syntax and parameters.