How to change user / group numbers in passwd/group?

[David Timms]

Eric wrote:
> 
> I am in the process of moving the content of an FC2 server to F7.  In 
> the process, I have to establish some new users with user and group 
> numbers 501 and 502.
> 
> Unfortunately, F7 in its infinite wisdom decided to assign 501 to user 
> "tclhttpd" and 502 to user "dbmail" (whatever they might be).  
> (vigorously begging the question of WHY!!! in the world it did that...)  
> :-(
They seem to be system account names, which in the past have ended up 
below 500, and I don't have those account names on my F7.
What web server and mail packages did you install ?

> 
> If I can't assign 501 and 502 to the users and groups they were on the 
> FC2 machine, a LOT of permissions problems will be created in a fairly 
> large and complex database and file structure.
> 
> What is the "right" way to assign different numbers to existing users 
> like "tclhttpd" and "dbmail"?
usermod --help
>  I know I can just go in there and edit 
> passwd and group but no doubt that will cause all sorts of unknown 
> problems elsewhere, for resources and files that depend on 501 and 502 
> being assigned to "tclhttpd" and "dbmail".  So, is there a "right" way 
> that updates everything else to whatever new user numbers I assign?

I found a script a while ago to achieve the changing of userid and grpid 
on files/directories. This worked well in bringing the id's inline with 
another server. I can't find it at the moment.

DaveT.