Basic PAM module that checks if a volume is mounted during login. It will display an error message and deny login if not.

gcc -fPIC -DPIC -shared -rdynamic -o pam_check_mounted.so pam_check_mounted.c

cp pam_ignore.so /lib/security/pam_check_mounted.so

chown root:root /lib/security/pam_check_mounted.so

chmod 755 /lib/security/pam_check_mounted.so

In /etc/pam.d/common-auth add this line:

auth requisite pam_check_mounted.so

O'Reilly guides:

[Writing PAM Modules, Part One] (http://www.linuxdevcenter.com/pub/a/linux/2002/05/02/pam_modules.html)

[Writing PAM Modules, Part Two] (http://www.linuxdevcenter.com/pub/a/linux/2002/05/23/pam_modules.html)

[Writing PAM Modules, Part Three] (http://www.linuxdevcenter.com/pub/a/linux/2002/05/30/pam_modules.html)