Hi...
-bash-3.00$ id -a
uid=1004(oracle) gid=101(oinstall) groups=101(oinstall),100(dba)
How to change gid from oinstall group to dba group??
Not sure on which OS you are, but usually you can just edit the /etc/passwd and the /etc/group to your needs.
Hi
I'm using Solaris 10
I'm afraid if i simply change the group, it will effect my oracle database
As long as oracle will be in the group dba, all will be ok, I think. If you just want to change the primary group, to dba, I see no problem. If you create a file or directory, it will have the users primary group, so you should know if that's what you want. To make sure everything is still accessable, you can keep oracle in the group orainstall.
On Solaris, I think you can just go on and edit the /etc/passwd and /etc/group. There is also some administration interface that you could use instead which's name I can't recall 
Tq zaxxon
It's better if i stick with oinstall group. 
Hi,
I think u can change the group
by using chgrp command
chgrp oinstall dba
Regards,
JeganR
Editing the passwd or group is no magic and not corrupting anything. Afaik, Solaris has no ODM like AIX for example so everything is in plain files, but as you like
@jegaraman
chgrp only changes the ownership on files/directories, not that of a user or group itself.