Pwck
File Integrity of Password Files
Proper password management, together with file integrity of your password files, is important for security of your system and users.
Summary
Password files on Linux are used to store user details, like your unique user ID and name. It defines who you are on the system, your access to files, and the permissions you have. Proper password management, together with file integrity of your password files, is important. It keeps your system and user accounts safe.
Password Files
For most Linux distributions there are two related files available: /etc/passwd and /etc/shadow. The first file defines what local users are available on the system. Fields include an identifier code (your user ID), your username, and an informational field named GECOS. This last field provides (optional) details about you, like contact details. The /etc/shadow file is a cloned file of /etc/passwd, with the exception that it does store the related password of users. It has different file permissions, to avoid others from snooping at your password, or a hashed form of it.