Anyone using Shadow files (as temp files) for critical apps?

Discussion in 'Apple' started by LOCOBOX, May 15, 2006.


    LOCOBOX Guest

    I would like to acquire some help on getting a shadow file process
    going, I have searched for this everywhere and can't be able to find
    a good tutorial. All I've found is:

    % hdiutil attach oed.dmg -shadow /tmp/oed.shadow -noverify

    I created a shadow file for a mounted drive (created from a .dmg).
    My problems are:

    1) the changes seem to get written to the shadow file, but once I
    can't seem to be able to delete the shadow file to get rid of the

    2) I saw someone do this for a program and they were running the
    shadow file for a mounted drive, that's why I wanted to do it for a
    mounted drive too (or I could do it for a folder???)... the problem
    with the mounted drive is that when I restart, the drive is gone and
    I have to recreated by the .dmg. (what's the point of this?)

    - I guess once I have a software (folder) that I don't want changed I
    can create a .dmg and launch the mount, then use the shadow file like
    that.. (is that how it would be most useful? are there better ways to
    use this?)

    Please help :)

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    LOCOBOX, May 15, 2006
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    Simon Slavin Guest

    I would like to acquire some help on getting a shadow file processgoing,

    Why ? I doubt that more than five people who read this group even
    know what a shadow file is. The answer to the question in your 'Subject'
    header is probably 'no'.

    Be aware that shadow technology is already built
    into Apple's Netboot services. If you're using Netboot (the only good
    reason I can think of to use shadow files) then you don't need to set this
    up manually.
    Probably because nobody does it. It's used /by/
    some services Apple provides, but unless you know a lot about the Mac OS
    you're probably not going to get this working properly and don't need
    /tmp/oed.shadow -noverify

    That should work.
    written to the shadow file, but once I
    You don't. Once the shadow file is detached, it can be
    Ah. Okay, I'm starting to get to the bottom of why you want to do

    An application folder doesn't need writing to. Generally, your
    applications are stored in a folder where only administrators have write
    privileges, so a mundane non-administrator user can't change them. That's
    all the protection you need.

    For those few badly-written applications
    (games, mostly) that expect to be able to change files in the same folder
    as they are (or subfolders of that folder) you can probably fool them with
    using aliases, to move the folders which they want to change to a place
    that a mundane user can change.

    Simon Slavin, May 17, 2006
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    Warren Oates Guest

    There's an example of shadow file usage in the hdiutil man pages. I'm
    not sure of what other uses the average user might make of shadow files
    though, other than to save space and time. If you only want to "write
    protect" a directory, you can do that with chmod or chown.

    Or is this an OS 9 thing? Mike Bombitch has a way of running Classic
    from a shadow file:
    that might be of interest.

    If you're only having problems with one app, there's a list of nasty
    ones here, and how to fix 'em:
    Warren Oates, May 18, 2006
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