Operating Systems

A package manager is a tool that automates installing, upgrading, configuring, and removing software. Each package manager maintains a list of software packages that can be installed, updated, and removed from the system. Package managers also provide tools to search for packages, install dependencies, manage configurations, and automate updates. Almost all packages can be found…

The mount command attaches a filesystem or device to a directory (the mount point) so its contents become accessible. The umount command detaches it. Key point: A device must be mounted before you can read or write to its files. Linux treats everything as a file — including devices and filesystems. a – mount options…

28 – fdisk command fdisk is a command-line tool for managing partition tables on HDDs, SSDs, and other storage devices. You can create, delete, resize partitions, change their types, or check their status. Key point: fdisk edits the partition table, not the filesystem. Always back up data before modifying partitions. a – fdisk fdisk is…

These three commands form the backbone of filesystem management on Linux. fsck checks and repairs filesystems, mkfs creates them, and dd copies raw data between devices and files. Together they let you build, verify, and clone storage at a low level. Key point: These tools operate on filesystems and raw devices — not on individual…

ping and traceroute are two of the most fundamental network diagnostic tools. ping tells you whether a host is reachable and how fast the round trip is. traceroute tells you which path packets take to get there, hop by hop. Key point: Both tools use ICMP (Internet Control Message Protocol) by default. Some networks block…

ip and netstat are two essential tools for inspecting and managing network configuration on Linux. The ip command is the modern replacement for the older ifconfig, route, and arp commands. netstat shows active connections, listening ports, and routing tables — though it’s being gradually replaced by ss on newer systems. Key point: ip is the…

ftp and wget both deal with transferring files over a network, but they serve very different purposes. ftp opens an interactive session where you can browse and manage files on a remote server. wget is a non-interactive downloader built for scripts and automation. Key point: FTP sends credentials and data in plain text — it’s…

ssh (Secure Shell) is the standard way to log into a remote Linux/Unix system and run commands on it. Unlike telnet or rlogin, everything sent over an SSH connection is encrypted — including your password. This makes SSH safe to use even over untrusted networks like the internet. Key point: SSH uses public-key cryptography for…

scp and sftp both move files between systems over SSH — meaning everything is encrypted. The difference is style: scp is a one-shot command (copy this file there and exit), while sftp is an interactive session (browse, upload, download, manage files on a remote system). Key point: Both tools use SSH for transport, so they…

locate and find both search for files, but they work in completely different ways. locate queries a pre-built database — it’s blazing fast but only as current as the last database update. find walks the filesystem in real time — it’s slower but always accurate and far more powerful. Key point: Use locate when you…