LFCS: Linux Foundation Certified System AdministratorDemo

On Linux systems using shadow password suites, the password field in /etc/passwd is replaced with the letter x for every user account. This value is not a valid encrypted hash; it simply signals to system utilities that the real encrypted password (and related aging information) resides in the more restrictively permissioned /etc/shadow file. This scheme keeps hashed passwords out of the world-readable /etc/passwd file, improving security.