Date   : Thu, 10 Nov 1983 17:46:00 PST
From   : MMOON.ES@PARC-MAXC.ARPA
Subject: Re: CPM prog. to change fcb wanted

DUPUSR2.ASM OR DUPUSR21.ASM are floating around on various RCP/Ms  &
will do what you want with a little extra effort. This program creates a
*duplicate* directory entry in a comand-line specified user area.  One
must then go back and delete the file in the original user area if
access to it from that user is not desired.  This second delete must be
followed by a <ctrl>-C to force a fresh read of the allocation vectors
into memory.  The sectors where the program or data reside have not, of
course, been physically nulled by the erasure, but by marking them as
deleted in *any* user area which has a directory entry for the
particular file, you have caused an update of the in-memory allocation
vector which will cause those sector bits in the bit mapped to toggle,
thus marking these sectors as free to be written into, which they are
not. The <ctrl>-C thus avoids a potential overwrite problem by renewing
the allocation vector.

I have been using DUPUSR21 for several months to very good effect under
ZCPR2, using it also to move files into different user areas as well as
making duplicate entries for the same file.  The program documents the
above mentioned side effect in the commented code.  Also, it will accept
wildcard file designations so an entire directory could be moved in this
manner.  Enjoy.


               MMoon.es