tty login fails without any error message

Question

When I try to log in via tty (Ctrl+Alt+FX) I get a prompt, e.g.:

laboratory login:

I can then type in the username and press enter but it immediately resets to the same prompt, with no error message and no password prompt. I am unable to log into my graphical environment, hence needing to use tty (I believe my desktop manager is not starting). What is going wrong?

Answer 1

That's because you're probably typing the wrong username: remember that upon user's creation, if the full name provided it's two words long and it contains uppercases (e.g. "John Smith"), it will default to the first word converted to lowercase (i.e. "john").

Before switching to a tty, open a terminal within your graphic environment by hitting Ctrl+Alt+t and run the command whoami: this will return the exact username to be used upon tty login.

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Since you can't access your graphical environment, try the following:

1. Shutdown the system
2. While booting, hold Shift to access grub2's menu
3. Select Advanced options for Ubuntu and hit Enter

4. Select your current kernel's recovery mode (e.g. Ubuntu 12.04 x.xx.xx-xx-generic (recovery mode)) and hit Enter

5. Select root - Drop to root shell prompt and hit Enter

6. Run cat /etc/passwd to see a list of all the users present in the system. Check your actual username
7. Run exit
8. Select resume - Resume normal boot
9. Try to login in a tty using the username recovered from the list

Answer 2

the workaround is to append somewhere in your kernel cmdline while in grub the parameter init=/bin/bash or /bin/sh or zsh whatever you use. also change ro to rw otherwise you need to mount -o remount,rw /dev/sdx /. do not forget to # out whatever comes after this parameter or append it at the end otherwise it will read the output after as a command in shell.