This Learn On Demand Pro Series is part of a Career Path: Become a System Administrator
Learners set a CentOS 7 Linux server to boot-up in a graphical user interface (GUI), command-line interface (CLI), or rescue mode, using systemd processes, in this hands-on virtual lab. Also, participants locate default and current startup modes for the server. This 45-minute IT Pro Challenge provides guided steps and hints, from start to finish. While working through each module and selecting the hint links, learners receive step-by-step help to complete the tasks. Screenshots show expected results upon executing the suggested command and provide a way for participants to check their work.
Those wishing to advance their careers as a systems administrator or skills in IT gain expertise and hands-on practice researching, coding, and troubleshooting using Linux terminal, in this lab. Learners also see the difference between SysV and systemd boot processes in Linux, as well as receive a handy table contrasting the two operations. As a result of doing this challenge, learners gain important troubleshooting skills for testing applications under development, isolating computing issues, and making server or network updates.
Identify Default and Current Server Startup Targets:
This section has users initiate the lab and research current and default boot configurations on the Linux server. Learners obtain helpful tips about displaying all the systemd subcommands and the differences between SysV and systemd. SysV, found in CentOS 6, uses runlevels, a scale from 0 - 6 defining the order services started after starting up the system. The newer CentOS 7, uses .target files. Targets act like containers that group systemd units, specific algorithms together. Linux specifies predefined targets making it easier to get into the CLI or rescue mode.
Change the Default Target from the GUI to the CLI using ‘systemctl’:
Users manually change system startup by the ‘systemctl’ command. The lesson shows changing from a GUI to a CLI boot and back again. Learners also see the need for root login to swap boot targets. In addition to getting practice with ‘systemctl,’ the instructions explain how ‘systemctl’ manages startup services.
Change to rescue mode using systemctl:
This module instructs learners on entering and exiting rescue mode using ‘systemctl.’ Getting to rescue mode, from the GUI, gives System Administrators a window to do maintenance and fix application performance issues that seriously impact the server system. Learners get familiar with cues indicating the system has switched to rescue mode.
View the Contents of .target Files:
Through this portion, learners view available, system target options after reboot. The user reads information about the target files, which includes description, documentation, and requirements. Furthermore, participants learn the system directory, where the target files and their documentation originate.
Learners that complete this challenge can easily configure boot settings to startup the Linux server in different modes: graphical, command line, and emergency modes. Learners demonstrate the following:
- Comparing the older SysV startup to the newer systemd startup.
- Switching from the CLI to the GUI target.
- Configuring the server to boot into CLI and GUI.
- Changing to the ‘rescue.target’ mode and then back to the GUI.
- Viewing the contents of the .target files.
Other IT Pro Challenge labs enhance Linux skills and server management.
- GUIDED CHALLENGE: Manage Services in Linux
- ADVANCED CHALLENGE: Can You Configure Kickstart Installations in Linux?
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