16.3.4. Module Arguments

PAM uses arguments to pass information to a pluggable module during authentication for some modules.

For example, the pam_userdb.so module uses secrets stored in a Berkeley DB file to authenticate the user. Berkeley DB is an open source database system embedded in many applications. The module takes a db argument so that Berkeley DB knows which database to use for the requested service.

A typical pam_userdb.so line within a PAM configuration file looks like this:

auth      required  pam_userdb.so db=<path-to-file>

auth      required  pam_userdb.so db=<path-to-file>

In the previous example, replace <path-to-file> with the full path to the Berkeley DB database file.

Invalid arguments are ignored and do not otherwise affect the success or failure of the PAM module. However, most modules report errors to the /var/log/messages file.