By Emmett Dulaney

The Linux Essentials exam covers the topic of the Linux operating system. This table shows the subtopics, weight, description, and key knowledge areas for this topic.

Breakout of Topic
Subtopic Weight Description Key Areas
Choosing an Operating System 1 Knowledge of major operating systems and Linux
distributions
Windows, Mac, Linux differences; distribution lifecycle
management
Understanding computer hardware 2 Familiarity with the components that go into building desktop
and server computers
Hardware
Where Data is Stored 3 Where various types of information are stored on a Linux
system
Kernel; processes; syslog; klog; dmesg; /lib; /usr/lib; /etc/; /var/log
Your Computer on the Network 2 Querying vital networking settings and determining the basic
requirements for a computer on a local area network (LAN)
Internet; network; routers; Domain Name Service; network
configuration

To adequately address these topics, focus on the following files, terms, and utilities: desktop configuration (GUI versus command line); dig; display types; drivers; free; hard drives and partitions; ifconfig; IPv4; IPv6; libraries; maintenance cycles (beta and stable); memory addresses; motherboards; netstat; optical drives; peripherals; ping; power supplies; processes and process tables; processors; system messaging and logging; programs; packages and package databases; ps; resolv.conf; route; ssh; system configuration; and top.

Here are the top ten items to know as you study for this domain:

  1. When run, every command spans at least one process; processes can be viewed with ps or top (which updates the display dynamically).

  2. Jobs can run in the foreground or background and be moved between the two. Jobs running in the foreground can be suspended by pressing Ctrl+Z.

  3. IPv4 uses 32-bit addresses, each divided into four octets. The first octet identifies the class of address (A, B, C). The address can be public or private.

  4. The ifconfig utility can be used to see the current IP configuration of the network cards.

  5. The ping utility is an all-purpose tool for testing connectivity. It sends echo messages to a specified host to see whether that host can be reached. You can use ping with the loopback address (127.0.0.1) to test internal configuration.

  6. The route utility displays the routing table and allows you to configure it.

  7. The netstat utility shows the current status of ports – those that are open, listening, and so on.

  8. The system log is /var/log/messages and this is where the majority of events are written to by the system log daemon (syslogd). Messages routed there can be viewed with the dmesg command.

  9. The logrotate command can be used to automatically archive log files and perform maintenance as configured in /etc/syslog.conf.

  10. You can manually write entries to log files using the logger command.