Linux administration

A Linux administrator keeps a fleet of machines predictable. Software arrives and is updated through a package manager rather than downloaded installers; disks are partitioned, formatted and mounted according to a plan; accounts and groups decide who may read which file; services start at boot and are restarted when they fall over; logs are read to learn why they did. Most of this happens over SSH on machines the administrator has never physically touched, and much of it is the same work that anyone renting a VPS or running a web server eventually has to do for themselves.

How LPIC-1 divides the ground

LPI's LPIC-1 objectives, currently version 5.0, are the clearest public map of the field, because they are written with no single distribution in mind. They run as ten numbered topics spread over two papers, and grouping them shows what the job rests on:

• Topics 101 and 102: the hardware the system sees, the boot sequence from firmware to a running system, disk layout, boot loaders, shared libraries and both big package families, Debian's and the RPM world's.
• Topics 103 and 104: working at the prompt, filtering text and searching it with regular expressions, starting and prioritising processes, creating filesystems, mounting them, and managing ownership, permissions and links.
• Topics 105 to 107: the shell environment and simple scripts, a short section on graphical desktops and accessibility, then administrative tasks such as accounts, scheduled jobs and localisation.
• Topics 108 to 110: system time, logging, mail transfer and printing, then IP basics, persistent network settings, fault-finding and client-side DNS, and finally host security and encryption.

Three routes to one competence

LPIC-1 and CompTIA's Linux+ are multiple-choice papers that stay neutral between distributions, with Linux+ reaching further into containers and security. Red Hat's RHCSA is the odd one out: it gives you live systems and a task list and marks what those systems do when time runs out, so there is nothing to recognise and nothing to guess. Employers whose servers run Red Hat Enterprise Linux or one of its rebuilds tend to name the RHCSA; elsewhere the choice matters less than the time spent at a prompt. LPIC-2 is the next rung for anyone who wants the engineering half of the job, from the kernel and advanced storage to running network services for other people.

The beginner's usual mistake is learning commands without learning the system underneath them. Someone who has memorised a hundred flags but cannot say what happens between the boot loader and the login prompt is stuck the first time a server refuses to start, which is precisely the moment an administrator is paid for. Learn the order in which things happen, where each part writes its logs and how to read a permission string, and the commands follow naturally. From here the work leads three ways: into scripting and automation, where repeated tasks become code; into servers and virtualisation; and on to containers and the cloud, which run on Linux almost everywhere.