Systems & Cloud

Linux Essentials

The operating system underneath servers, cloud instances and — increasingly — network devices themselves. Two working chapters: the filesystem, permissions and process model every engineer must navigate, and the networking toolkit for configuring and troubleshooting Linux hosts.

read in order, or dip in: 2 chapters
updated 31 Aug 2026: Free — no signup

Contents

01The Linux Filesystem, Permissions and ProcessesLinux presents everything as one file tree rooted at /, with conventional homes for binaries (/usr/bin), configuration (/etc), logs (/var/log) and devices (/dev). Every file carries an owner, a group and three permission triads — read, write, execute for user, group and other — managed with chmod, chown and umask; processes are inspected with ps and top, managed by systemd, and privileged work flows through sudo.
02Linux Networking Commands Every Engineer Should KnowModern Linux networking runs through the ip command — ip addr, ip route, ip link — with ss for sockets, ping and traceroute for path testing, and dig for DNS; configuration persists via Netplan or NetworkManager depending on distribution. The troubleshooting ladder is fixed: link up, address present, route known, DNS resolving, socket listening, firewall permitting.

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