As an alternative to interacting with bash at runtime or providing the password as an argument to the mount command, you may be able to put the authentication credentials in a secure file and have the mount command read them from there.

How and whether you can do this will depend on your file system type. For example, with a CIFS filesystem (mount.cifs) you can either provide the credentials option to specify a file containing the username and password or set the PASSWD_FILE environment variable to specify a file containing the password.