Knowledge Base

Server authentication is the process of verifying your identity to gain authorized access to a remote system, hosting control panel, or online service. The three dominant methods are password-based SSH, SSH key-pair authentication, and web-based control panel login — each…

The `history` command in Linux is a built-in Bash shell utility that records, displays, and manages every command executed in a terminal session. It reads from and writes to `~/.bash_history`, a plain-text file in each user's home directory, enabling you…

GNU Screen is a terminal multiplexer that lets you create, manage, and persistently resume multiple independent shell sessions from a single terminal connection. When you detach a Screen session, every process running inside it continues executing in the background —…

Nginx can listen on multiple ports simultaneously by adding multiple `listen` directives inside one or more `server` blocks within its configuration. Each `listen` directive binds Nginx to a specific IP/port combination, allowing a single server instance to handle HTTP, HTTPS,…

`useradd` is a low-level binary utility available on virtually every Linux distribution that creates user accounts by directly writing to `/etc/passwd`, `/etc/shadow`, and `/etc/group`. `adduser` is a higher-level wrapper script — typically written in Perl on Debian-based systems — that…

Mastering MySQL database import and export operations from the command line is a non-negotiable skill for any database administrator or backend engineer. The `mysqldump` utility exports a database into a portable `.sql` file containing all DDL and DML statements required…

MySQL's `FLUSH` statement forces the server to reload internal caches, close and reopen log files, reset status counters, and synchronize in-memory state with on-disk structures — all without requiring a server restart. This makes it one of the most operationally…

PHP-FPM (PHP FastCGI Process Manager) is a high-performance process manager that handles PHP execution as a separate service, decoupled from the web server. Restarting PHP-FPM applies configuration changes from `php.ini` or `php-fpm.conf`, reclaims leaked memory in long-running worker pools, and…

mysqldump is a command-line utility bundled with MySQL and MariaDB that generates logical backups by serializing database objects and data as a sequence of SQL statements. The resulting dump file can recreate an identical database on any compatible server, making…

Google Public DNS is a free, globally distributed Domain Name System resolver operated by Google, reachable at 8.8.8.8 (primary) and 8.8.4.4 (secondary). Replacing your ISP's default DNS servers with these addresses can reduce DNS lookup latency, harden your resolver against…