Announcing the release of Fedora 16 Beta!!

Michael Cronenworth mike at
Tue Oct 4 15:28:28 UTC 2011

suvayu ali wrote:
> I see that usermod can do this[1], but I'm not sure if there will be
> conflicts with existing files after the change.

If you are using plain authentication and not something like LDAP you 
can use usermod and edit groups with groupmod. You can manually edit 
/etc/passwd or /etc/group, but you will have to manually run "chown" 
across all files with the old UID/GID to update them to the new UID/GID.

After you make the GID change you will have to change the ownership of 
your home to match the new GID:

# chgrp -R group /home/user

(per the groupmod[1] man page)

Also, delete any /tmp files with your old UID and chown files outside of 
/home. (per the usermod[2] man page)

# chown -R user:group /opt/foo/dir

[1] Any files that have the old group ID and must continue to belong to
     GROUP, must have their group ID changed manually.
[2] The ownership of files outside of the user´s home directory must be
     fixed manually.

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