Bdtyktl

I am trying to autologin and auto startx on my ubuntu minimal installation
(15.04 Vivid Velvet 32bits, mini.iso)
I am following several guides that I found but none of them work (the startx part works, but not the autologin)

For example:
https://rowen121.wordpress.com/2011/09/14/enable-automatic-login-and-startx-in-ubuntu/
https://wiki.ubuntuusers.de/autologin

One of the problems is everytime I go and look for the file they tell me to edit, it's not there.
When I do sudo nano whatever the file, it is empty (tty1.conf for example, or inittab)
In all the guides they say to uncomment a line and add another, but all those files are empty for me.
Maybe it is because they refer to Debian and things change.

I have managed to make it work installing nodm.
Then I don't need to write my username nor password, and then, it auto startx (I added startx in .bash_profile), and finally takes me to i3-wm. I haven't installed a display manager (well, just nodm as the last option to try) nor desktop environment.

I would like to get it working without the need of installing a display manager (rungetty/mingetty/getty/whatever works and it's easy on resources)
Please if you know the steps that work for you and ubuntu, or a guide that I can follow I would appreciate it.
Thanks in advance

Note: nothing is encrypted

It seems you were right Serg, Ubuntu 15.04 now uses systemd, and apparently things have changed.
So I kept on searching now for systemd autologin and got it working.
I found this guide that served me well:
http://memo-linux.com/debian-8-systemd-autologin-sans-display-manager/

This is what I did:

sudo mkdir -pv /etc/systemd/system/getty@tty1.service.d/

sudo nano /etc/systemd/system/getty@tty1.service.d/autologin.conf

and edited the file as follows:

[Service]

ExecStart=

ExecStart=-/sbin/agetty --autologin username --noclear %I 38400 linux

Change "username" with yours.

Save and close (CTRL+O, CTRL+X)

Now:

systemctl enable getty@tty1.service

Write your password (I was asked twice)

That would be for the autologin part.
Next, to start X automatically, continue with this:

sudo nano ~/.bash_profile

and edit that file so it reads:

[[ -z $DISPLAY && $XDG_VTNR -eq 1 ]] && exec startx

Save and close (CTRL+O, CTRL+X)
(Source: wiki archlinux Autostart_X_at_login)

At this point I found another possibility for that file here:
https://unix.stackexchange.com/questions/42359/how-can-i-autologin-to-desktop-with-systemd

if [[ -z $DISPLAY ]] && [[ $(tty) = /dev/tty1 ]]; then

 exec startx

fi

But I haven't tested it and I don't really know the difference, sorry.

In this last link they advised to do a last step
"You will have to modify your ~/.xinitrc to start your desktop environment, how to do that depends on the DE"
So I did:

sudo nano ~/.xinitrc

and added this line

exec i3

Save and close (CTRL+O, CTRL+X)

Last thing to do:

sudo reboot

Now it auto logins and auto starts X, and no display manager was needed.
I think I read if you already have a display manager you have to remove it first.
I hope this can be useful for you. Feel free to comment and improve it.