General :: How To Change User Groups Automatically

I've created a set of users using the newusers command. Unfortunatelly ive messed up and added all users to the 1000 group as primary group instead of giving the group argument as null what would add them to a new group. To make things clear:

The entries should be

user:password:::User Name:/home/user:/bin/bash

but I did

user:password::1000:User Name:/home/user:/bin/bash

I need to create the missing groups. A simple fix could be do a for loop creating a group with the name of each user in my file and then adding the users to it. Are there any dangers of doing it? What impact could this change have? Are there any safer ways?

A combination of the following commands:

Quote:

Add users to a group with the gpasswd command:

# gpasswd -a [user] [group]

To delete existing groups:

# groupdel [group]

To remove users from a group:

# gpasswd -d [user] [group]

If the user is currently logged in, he/she must log out and in again for the change to have effect.

Quote:

for i in (names)
do groupadd $i
gpasswd -a $i $i

Assuming I've created all users in group 1000 I could remove them from it with

Quote:

# gpasswd -d [user] [group]