Jeff Sohrt writes:

>Then often is the case, that we do another :purgelink and build a new file
>which subsequent users then access.   IF the first user never closes the
>program, you're saying the file is actually still on disk taking up room
>with no directory entry.  I suppose we could have multiple chunks of disk
>space for each purgelink.

The file isn't actually deleted until the last user closes it; only the
directory entry is gone. This is exactly what you want: it's not nice to
overwrite the code of a running program.

Internally, once the directory entry is removed, a PURGELINK (or an rm)
modifies the file's in-memory control information to make it look like a
new, unnamed file. MPE then treats the file just like any other new file:
by default, newly-created files don't get a directory entry unless and
until they're closed with the "save permanent" option, and are purged
unless explicitly saved. This is a mechanism that's been in MPE since
forever; as Gavin says, it's a well-defined and perfectly safe operation.
In fact, temporary files don't have directory entries either.

-- Bruce



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