Re: user flags in public temp space (was Re: chflags() [heads up])

From: Tim Fletcher (tim@NIGHT-SHADE.DEMON.CO.UK)
Date: Fri Aug 06 1999 - 18:43:59 PDT

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    > I think I defeated myself in trying to explain the implementation I was
    > trying to describe.  For each user, when they login, a virtual /tmp is
    > created and that is shared between all sessions that user has.  This is
    > setup at login time and is carried forth to all children, root or not,
    > and cannot be reset (somewhat akin to chroot) unless devious methods are
    > employed (i.e. write to /dev/mem).
    >
    > So if I have 10 logins to host foo, each login sees the same /tmp, even
    > the root shells I generate via su/sudo in half.  If I login as root, I
    > don't have the same /tmp (I get a different one).  cron/at jobs would
    > be no different.  So the `real' /tmp could even be 755 root.wheel.
    
    I see what you are getting at basically /tmp becomes an extention to the
    per user memory space. (bad analogy on my part but I can't think of a
    better one :)
    
    Although it does rather cripple /tmp in another way: That of sharing
    information between users. If I tell another user that the file s/he wants
    is in /tmp (as my /home/tim dir is 711 with most files 600) I don't have
    to mess with file perms and s/he doesn't have to get the exact right name
    to read the file.
    
    You also may have problems as the /tmp space you suggest (~/tmp mapped to
    /tmp) is then inside a users quota'ed directory which is often a bad idea,
    this blocks logins as no tmp space is avalible hence login fails, so you
    can clear out your ~/tmp space, a chicken / egg problem :). You are all
    well and good quotaing or mounting /tmp to stop / filling up but the point
    is the the /home and /tmp quotas should be different.
    
    --
    
          Tim Fletcher                  .~.
                                        /V\       L   I   N   U   X
       tjdf@st-andrews.ac.uk           // \  >Don't fear the penguin<
    tim@night-shade.demon.co.uk       /(   )\
                                       ^^-^^
    
    "First they ignore you. Then they laugh at you.
       Then they fight you. Then you win." - Gandhi
    



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