Move All Users to a New System

Ubuntu Tutorials - Herong's Tutorial Examples

∟Move All Users to a New System

This section provides a tutorial example on how to move all users to a new Ubuntu system.

How To Move All Users to a New System? If you are replacing an old Ubuntu system with a new system, you can follow this tutorial to move all users and their files to the new system.

1. Do not add any regular users to the new system. This avoids user ID collision when moving old users to the new system. The following command should returns no output:

root# awk -F: '($3>=1000) && ($3!=65534)' /etc/passwd

Note that the third field in the "etc/password" file is user ID, which starts from 1000 for non-system users, User id 65534 is for "nobody", which is a dummy user.

2. Extract user information, including user names, user passwords, group names and group passwords on the old system:

herong$ sudo awk -F: '($3>=1000) && ($3!=65534)' /etc/passwd > passwd.old

herong$ awk -F: '{print $1}' passwd.old |tee - |sudo egrep -f - /etc/shadow > shadow.old

herong$ sudo awk -F: '($3>=1000) && ($3!=65534)' /etc/group > group.old

herong$ awk -F: '{print $1}' group.old | tee - |sudo egrep -f - /etc/gshadow > gshadow.old

3. Transfer and restore user information on the new system:

root# cat passwd.old >> /etc/passwd
root# cat shadow.old >> /etc/shadow
root# cat group.old >> /etc/group
root# cat gshadow.old >> /etc/gshadow

4. Verify one old user on the new system:

root# su herong
(Enter the old password)

bash-4.4$ exit
exit

5. Move user home directories:

# on old system:
herong$ sudo tar -zcvpf /tmp/home.tar.gz /home

\ transfer home.tar.gz to the new system
\ which may require a large amount of disk space

\ on new system:
root# cd /
root# tar -zxvf /tmp/home.tar.gz

6. Login the new system with one old user:

root# ssh herong@newhost
(Enter the old password)

herong$ pwd
/home/herong

6. Move user email files:

# on old system:
herong$ sudo tar -zcvpf /tmp/mail.tar.gz /var/spool/mail

\ transfer mail.tar.gz to the new system,
\ which may require a large amount of disk space

\ on new system:
root# cd /
root# tar -zxvf /tmp/mail.tar.gz