Password aging and account aging are different things, and confusing them is one of the most common mistakes in user administration. Password aging controls how long a password remains valid. Account aging controls how long the account itself remains valid, regardless of the password. A contractor hired for six months needs an account that stops…
A password that never expires is a password that is eventually compromised. An attacker who obtains a password hash has unlimited time to crack it, and the longer the password remains valid, the wider the window during which a leak is exploitable. Password aging is the policy that forces passwords to change on a schedule,…
Deleting an account is not the reverse of creating one. The account leaves traces: a home directory, a mail spool, a crontab, running processes, file ownership across the filesystem, and entries in /etc/passwd, /etc/shadow, /etc/group, and /etc/gshadow. The userdel and groupdel commands remove the account entries, but the rest of the cleanup is the administrator’s…
A group is a named collection of users. It exists so that permissions can be granted to many users at once. Instead of chowning a file to a dozen users, an administrator chowns it to a group and adds the users to that group. Linux uses groups in two ways: as a primary group attached…
User management is the foundation of Linux system administration. Every process runs as a user, every file is owned by a user, and every permission decision is ultimately a decision about which user can do what. The LFCS exam treats user administration as essential, and the commands involved — useradd, usermod, passwd, chage — appear…
A <Teleport> normally resolves its target the moment it mounts. If the target element does not exist yet, Vue logs a warning and renders nothing. This is a common problem when the target is rendered by the same component tree: a modal might teleport to a container that appears later in the template, or a…
A modal dialog has a layout problem. It needs to appear centered on the screen, above everything else, with a backdrop that covers the entire page. If the modal is rendered inside a deeply nested component, its parent’s CSS can interfere: an overflow: hidden, a transform, a z-index stacking context, or a position: relative ancestor….
A component that loads data asynchronously has three states: loading, loaded, and failed. The traditional way to handle these is a v-if chain: show a spinner while loading is true, show the content when data is present, and show an error when error is set. Every component repeats this pattern, and every parent repeats the…
A Vue application ships as JavaScript. The larger the application, the larger the bundle, and the longer the initial load. A user who lands on the login page does not need the code for the settings panel, the admin dashboard, or the rich text editor. Loading all of it upfront wastes bandwidth and delays the…
A parent component can reach into a child and call its methods or read its state by holding a template ref. In Vue 2, everything on the component instance was reachable by default. In Vue 3 with <script setup>, the script’s bindings are closed by default, and the parent sees an empty object unless the…