"aliasing" users - what can I break?

[sjau]

Hiho

I just wonder what can I break when I "alias" users by giving them the same UID?

Current situation:

I have setup a new user, changed his default shell to MySecureShell and chrooted him to /var/www/web21

Then I changed his UID to match the one of the user "web21" so that this new user can use his own login and be able to "edit" files as "web21"

[falko]

It could happen that emails go to the wrong user, or that you get permission problems (for example in FTP).

[sjau]

that user doesn't get emails at all.... and the permission things, aren't permissions decided upon the UID and GID?

[falko]

and the permission things, aren't permissions decided upon the UID and GID?
Yes, but I'm not sure if it'll work without problems. :o