title: Directory remapping between users or processes on Linux?
body: <p>For example, I want to redirect the directory /data between users.
  When user1 access /data, it accesses /data1 actually.
  When user2 access /data, he accesses /data2 actually.</p>
  
  <p>What technology should I use? cgroups? unionfs? others? I'm sorry I'm a newbie.</p>
  
  <p>More advanced, redirection between processes.
  process1 accesses /data1 as /data ,
  process2 accesses /data2 as /data .
  How can I do that?</p>