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I was following the steps from this link I was trying to set it so I could use my webcam and face recognition to unlock my computer. Whenever I open the terminal or power up I get this message: ERROR: object '/usr/lib/libv4l/' from /etc/ cannot be preloaded: ignored. Does anyone know the code lines to undo/remove it?

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your question's title mentions PAM installation issues. Could you please edit your question and clarify what exactly have you tried to install and provide links to any tutorials that you followed? – papukaija Jul 22 '13 at 12:23

The linked tutorial in your question is very old and in fact the face authentication software seems to be written for older Ubuntu that use Gdm as login manager and not LightDM. Moreover, I checked the Launchpad page of the PPA mentioned in the tutorial and the PPA only has packages for Natty, Maverick and Lucid (which all are unsupported). Therefore, there is probably no way to get face authentication to work with that tool and I am not surprised that you get error messages in a recent Ubuntu release.

My advice is that you remove the tool completely from your system. The tutorial suggests that you can remove it with following commands:

cat /etc/pam.d/gnome-screensaver | sed 's:auth sufficient pam_face_authentication\.so enableX::g' | grep -v '^$' > temp; sudo mv temp /etc/pam.d/gnome-screensaver
cat /etc/pam.d/gdm | sed 's:auth sufficient pam_face_authentication\.so enableX::g' | grep -v '^$' > temp; sudo mv temp /etc/pam.d/gdm
sudo pam-auth-update --package face_authentication
sudo rm -f /usr/share/pam-configs/face_authentication
sudo apt-get install ppa-purge
sudo apt-get purge pam-face-authentication
sudo ppa-purge ppa:antonio.chiurazzi

I found one an other question on face authentication but its answers basically link to this broken tool. Hence, you may wish to open a new question if you want find an alternative tool to get face authentication working.

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