File Management - IBM

Redirecting files
64 File Management V4R5
v From the merged display of all overrides, you can request the display that is not
merged, as in “Displaying overrides with WRKJOB: scenario” on page 58.
v From the unmerged display of all overrides, you can request the merged display.
v From the merged display of all overrides, you can request a merged detail
display of any override, equivalent to the command in “Displaying merged file
overrides for one file: scenario” on page 58.
v From the merged display of all overrides, you can request a display of all the
individual overrides that contributed to the merged display, showing the level
(call level or job level) for which each was requested.
v From either the display of contributing overrides or the display (not merged) of
all overrides, you can request a detail display of the override for a particular file
at a single call level.
File redirection lets you use overrides to direct data input or output to a device of
a different type; for example, to send data that was intended for a diskette to a
printer instead. This use of overrides requires somewhat more foresight than the
override applications listed above, because the program must be able to
accommodate the different characteristics of the two devices involved.
To override to a different type of file, use the override command for the new type
of file. For example, if you are overriding a diskette file with a printer file, use the
Override with Printer File (OVRPRTF)command.
This section applies to using an application program only. System code may or
may not support file redirection. Refer to “Effect of overrides on some commands”
on page 35 for rules on how system code processes overrides.
You use the OVRDBF command to redirect a file to a Distributed Data
Management (DDM) file. If the remote system is another AS/400 system, all
normal rules discussed in this chapter apply. If the remote system is not an AS/400
system or System/38, then normally you should not specify an expiration date or
end-of-file delay. For more information, refer to the Distributed Data Management
book.
When you replace the file that is used in a program with another file of the same
type, the new file is processed in the same manner as the original file. If you
redirect a field-level file, or any other file that contains externally described data,
you should usually specify LVLCHK(*NO) or recompile the program. Even when
you turn level checking off, the record formats in the file must remain compatible
with the records in the program. If the formats are not compatible, the results
cannot be predicted.
Overrides that have a TOFILE parameter value other than *FILE remove any
database member specifications that may be on overrides applied at higher call
levels. The member name will default to *FIRST unless it is specified with the
change to the file name or library or on another override at a lower call level.
If you change to a different type of file, the system ignores device-dependent
characteristics and records that the system reads or writes sequentially. You must
specify some device parameters in the new device file or the override. The system
uses defaults for others. The effect of specific redirection combinations is described
later in this section.