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Trailing-Edge - PDP-10 Archives - BB-BT99U-BB_1990 - 10,7/backup/backup.rno
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BACKUP %6(701) has support for pathological names.  This change was
added mainly due to our own in-house requirements, but surprisingly,
the risks involved were minimal.  It amounted to breaking the logical
name into its individual components, and creating the equivalent
CHECK, SAVE, or  RESTORE command.  BACKUP always has generate two
filespecs for each entity in a CHECK, SAVE, or RESTORE command,
even when a single filespec was specified by the user.  This behavior
continues.  The following examples illustrate this and how logical
names are handled.
.SKIP 1
A simple SAVE command.
.LITERAL

	.PATH FOOP: = DSKC:[10,56,MTCERT],DSKC:[10,56,WHO]
	.R BACKUP
	/SAVE FOOP:

	 Logical name translations:
	 SAVE    DSKC:*.*[10,56,MTCERT] = DSKC:*.*[10,56,MTCERT], -
		 DSKC:*.*[10,56,WHO] = DSKC:*.*[10,56,WHO]

	! 10,56 DSKC
	" Done

.END LITERAL
.SKIP 1
A SAVE command with aliasing.
.LITERAL

	.PATH FOOP: = DSKC:[10,56,MTCERT],DSKC:[10,56,WHO]
	.R BACKUP
	/SAVE DSKB:[10,7,*] = FOOP:

	 Logical name translations:
	 SAVE    DSKB:*.*[10,7,*] = DSKC:*.*[10,56,MTCERT], -
		 DSKB:*.*[10,7,*] = DSKC:*.*[10,56,WHO]

	! 10,56 DSKC
	" Done

.END LITERAL
.SKIP 1
A simple RESTORE command.
.LITERAL

	.PATH NEWWHO: = DSKT:[10,56,NEWWHO]
	.R BACKUP
	/RESTORE NEWWHO: = DSKB:[10,7,WHO]:

	 Logical name translations:
	 RESTORE DSKT:*.*[10,56,NEWWHO] = DSKB:*.*[10,7,WHO]

	! 10,7 DSKB
	" Done

.END LITERAL
The CHECK command has always been sensitive to the order of the files
on tape vs_. those on disk.  This was "aspect" of BACKUP is caused by
the fact that files are not necessarily save to tape in the same
order that they are specified in the SAVE command.  BACKUP copies
files to tape based on their position in the specified directories.
This behavior has not changed, but it may be more easily induced
through the use of logical names, since the order of the directories
in a logical name does not necessarily have to match their position
on disk.