Problem in Loggin In due to incorrect editing of Pam.auth File

[shailesh_paranjpe]

I recently added fprint demo for logging in using my finger print scanner. However, while editing the /etc/pam.d/common-auth file, I have edited it incorrectly.

Basically, I have inputted some wrong lines in the same. Due to this, I am unable to login into Kubuntu at all. It is not accepting my password although I am sure I am typing it correctly.

How to edit this file by dropping to shell prompt and making my changes roll back? Please advise.

Thanks

Shailesh Paranjpe

[Snowhog]

If you are familiar with, you can use nano (the command line editor) once you have logged in to the root shell (single user).

[shailesh_paranjpe]

Thanks Snowhog. Will give it a try. By the way, how to login my username and password with root? or do I not need to login with my username and just dropping to root in shell is sufficient to edit the file. And what do you mean by single user?

[shailesh_paranjpe]

Please reply. I am unable to edit the common-auth file since after editing the previously changes done, the system is not allowing me to save the file. The warning displayed is that the file is read only. Therefore, I am unable to login and use Kubuntu at all.

[shailesh_paranjpe]

I used nano to edit the common-auth file. But after making the required changes when I attempt to save the file, it does not allow me to save. It says, error writing/etc/Pam.d/common-auth: read only file system. Why is the fully system read only of I have dropped to the shell prompt already. Moreover, it is not allowing me to login with my username and password from root prompt. How to overcome this deadlock?

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[Snowhog]

Use sudo nano.

[shailesh_paranjpe]

Yes, I had already used sudo nano. However, as it otherwise happens, system did not ask for the password (despite the fact that I had not logged in the root shell as super user). Therefore that may be the reason that the system is not allowing me to save the file. How to make the root editing as super user?

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[shailesh_paranjpe]

Yes, I could figure it out. I used Ubuntu from USB Stick and used Sudo nano to edit the file and undo the changes that I had done. Ubuntu on USB Stick did not require me to use my password for editing the file under sudo command and the problem was solved. This thread can be now closed. Thanks.