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SL5net
Asked: 2021-01-07 06:48:46 +0800 CST

How reinstall ubuntu new userName without losing right to read my backuped data?

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I know this question has already been asked a few times quite similar.

And this answer could probably help me a lot: change user 'peter' to 'paul'

But I am afraid of experimentation in this case. So I better ask before that.

How reinstall (K)Ubuntu with different user-name without losing right to read my backuped data (produced daily with Back_in_Time) from my Data-HDD?

I think I really screwed my computer up and I'm pretty sure that reinstalling is my only option (strange errors like e.g. invisible GUIs.

Over time I have created an SH script which installs almost everything later automatically. Therefore installing the tools and apps later should probably not be a very big problem.

I think it might be a good opportunity to finally use a better username.

system-installation

1 Answers

  1. Best Answer

    Linux file permissions and ownership are actually defined by the UID (User ID) and not the actual username. The username itself is just there to help make it user readable. If you run sudo grep $USER /etc/passwd you will see a line like the following:

    terrance:x:1000:1000:Terrance,,,:/home/terrance:/bin/bash

    The above shows my UID as 1000. Which means that as long as my username has a UID of 1000 I will be able to see my files.

    When you install Ubuntu for the first time on the computer it defaults to UID 1000 for the first user created when you type in the username you want.

    If you run ls -n in your home folder you will see something like the following:

    terrance@terrance-ubuntu:~$ ls -n
total 66076
-rw-rw-r--  1 1000 1000        0 Dec  2 16:55  adp.log
drwxrwxr-x  2 1000 1000     4096 Nov 29 08:06  bin
drwxrwxr-x  4 1000 1000     4096 Dec 15 15:35 'Calibre Library'
drwxrwxr-x  2 1000 1000     4096 Nov  3 11:48  data
drwxr-xr-x  2 1000 1000     4096 Dec 20 21:09  Desktop
drwxr-xr-x  9 1000 1000     4096 Dec 16 07:41  Documents
drwxr-xr-x 27 1000 1000     4096 Jan  5 22:52  Downloads
-rwxrwxrwx  1 1000 1000     1331 Nov 28 17:07  getintip.bsh
-rw-rw-r--  1 1000 1000       23 Dec 18 08:10  HomeIP
-rw-rw-r--  1 1000 1000 16697736 Oct 22 14:28  licenses.txt
-rw-rw-r--  1 1000 1000       83 Aug 27 07:58  links.txt
-rw-rw-r--  1 1000 1000      797 Nov 29 20:57  list-fftabs.py
-rw-------  1 1000 1000    20712 Dec 11 22:25  mbox
drwxr-xr-x  2 1000 1000     4096 Dec 26 20:45  Music
drwxrwxr-x  4 1000 1000     4096 Sep 26 21:48  Notebooks
drwxr-xr-x 12 1000 1000     4096 Oct 31 22:29  NVIDIA_CUDA-11.1_Samples
drwxr-xr-x  7 1000 1000     4096 Dec 12 08:02  Pictures
drwxr-xr-x  2 1000 1000     4096 Sep 26 14:23  Public
drwxrwxr-x  2 1000 1000     4096 Jan  5 12:32  scripts
drwxr-xr-x 14 1000 1000     4096 Dec 30 17:03  snap
drwxrwxr-x  3 1000 1000     4096 Oct  7 08:21  Steam
drwxr-xr-x  2 1000 1000     4096 Sep 26 14:23  Templates
-rwxrwxr-x  1 1000 1000      261 Dec 14 09:59  test.bsh
-rw-rw-r--  1 1000 1000      140 Oct 23 09:17  testfile
-rw-rw-r--  1 1000 1000      150 Dec 14 11:06  test.txt
-rwxrwxrwx  1 1000 1000     1825 Nov  1 07:05  things.bsh
drwxrwxr-x  3 1000 1000     4096 Jan  5 17:52  tmp
-rw-rw-r--  1 1000 1000       69 Nov  6 21:16  tty_firefox
-rw-rw-r--  1 1000 1000 50822163 Aug 14 21:01  ubuntu-unleashed-2021.epub
drwxr-xr-x  2 1000 1000     4096 Sep 26 14:23  Videos
drwxrwxr-x  3 1000 1000     4096 Nov 30 13:54 'VirtualBox VMs'
drwxrwxr-x  2 1000 1000     4096 Oct 27 11:04 'Winamp Skins'

    The above shows that all the files and folders in my home directory are owned by my UID.

    So, if you reinstall your OS and as long as your new username has a matching UID, you shouldn't have any issues being able to read your backed up data as long as its permissions and ownership match your existing UID. You also can also create the user manually to have that UID if you need with the following command:

    sudo adduser -u 1000 <username>

    Hope this helps!

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