Linux Essential System Services - dummies

By Emmett Dulaney

The Linux+ certification exam from CompTIA covers the topic of essential system services. This table shows the subtopics, weights, descriptions, and key knowledge areas for this topic.

Breakout of Domain 108
Subtopic Weight Description Key Areas
Maintain system time 3 Properly maintain the system time and synchronize the
System logging 2 Configure the syslog daemon Configure the logging daemon to send log output to a
Mail Transfer Agent (MTA) basics 3 Commonly available MTA programs Be able to perform basic forward and alias configuration on a
Manage printers and printing 2 Manage print queues and user print jobs Use both CUPS and LPD

To adequately address these topics, focus on the following files, terms, and utilities: /etc/cups, /etc/localtime, /etc/ntp.conf, /etc/timezone, /usr/share/zoneinfo, ~/.forward, CUPS config files/tools/utils, date, exim, hwclock, klogd, logger, lpd legacy interface (lpr, lprm, lpq), mail, mailq, newaliases, ntpd, ntpdate,, postfix, qmail, sendmail, syslog.conf, syslogd.

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

  1. The Network Time Protocol daemon (ntpd) maintains the time on all servers using NTP.

  2. The hwclock command can be used to display the date and time of a system’s hardware clock (also known as the real-time clock).

  3. The time zone is configured in the /etc/timezone file. Local time is likewise configured in /etc/localtime.

  4. The sendmail service is a general purpose SMTP program used for sending e-mail between servers.

  5. The mailq command shows a list of messages in the mail queue and works sendmail.

  6. The newaliases command builds a database for the mail aliases file.

  7. Mail can be forwarded from one e-mail address to another using a .forward file.

  8. Line printers are rarely used anymore, but support for them remains. The primary utilities associated with them were/are as follows: lpr (to submit a print job), lpq (to see the print queue), and lprm (to remove queued print jobs).

  9. The Common Unix Printing System (CUPS) is the most common printing interface used on Linux today. It provides support for the line-printer daemon as well as for Server Message Block (SMB).

  10. The kernel logging daemon (klogd) logs Linux kernel messages.