I am curious whether there is a standard expected behavior and whether it is considered bad practice when creating more than one account on Linux/Unix that have the same UID. I've done some testing on RHEL5 with this and it behaved as I expected, but I don't know if I'm tempting fate using this trick.
As an example, let's say I have two accounts with the same IDs:
What this means is:
- I can log in to each account using its own password.
- Files I create will have the same UID.
- Tools such as "ls -l" will list the UID as the first entry in the file (a1 in this case).
- I avoid any permissions or ownership problems between the two accounts because they are really the same user.
- I get login auditing for each account, so I have better granularity into tracking what is happening on the system.
So my questions are:
- Is this ability designed or is it just the way it happens to work?
- Is this going to be consistent across *nix variants?
- Is this accepted practice?
- Are there unintended consequences to this practice?
Note, the idea here is to use this for system accounts and not normal user accounts.