Manage Software Configurations

In Chapter 6, “Build and Install Software,” you learned about managing software. In this chapter the focus shifts toward software configuration. You will learn how to manage software repository configurations and how to configure the kernel. You will also learn how to configure common system services, such as SSH, NTP, and syslog.

This chapter provides information on the following topics: updating configuration files, configuring kernel options, configuring common system services, and localization.

Updating Configuration Files

This section explores the package management configuration files that you should know how to update.

Procedures

If you upgrade a package, you might need to restart or reload a service. Typically the documentation that comes with the software package should indicate if a restart or reload is required. You also might need to restart or reload a service if changes are made to the configuration file for the software. This section addresses these procedures.

Restart Service

The restart option is used with the systemctl command to restart a service that is currently running. A restart can make the service unavailable for a short period of time.

Syntax:

systemctl restart process_name

You can determine whether a service is currently running by using the active command:

# systemctl active cups
enabled

Reload Service

The reload option is used with the systemctl command to reload a service that is currently running. This command does not stop the service but rather has the service reread its configuration file and change its behavior based on changes in the configuration file.

Syntax:

systemctl reload process_name

You can determine whether a service is currently running by using the active command:

# systemctl active cups
enabled

.rpmnew

When RPMs are installed, they might overwrite the default configuration files of the software package as new configuration settings are added or older configuration settings are removed.

The overwriting of the configuration files can lead to frustration if the system administrator has spent time and effort creating a customized configuration file. As a result, software developers might choose to place the new configuration file contents in a file called .rpmnew. Then a system administrator can review the .rpmnew file and determine which new settings should be incorporated into the primary configuration file.

Another technique is for the software developers to use a .rpmsave file, as described in the next section.

.rpmsave

When RPMs are installed, they might overwrite the default configuration files of the software package as new configuration settings are added or older configuration settings are removed.

The overwriting of the configuration files can lead to frustration if the system administrator has spent time and effort creating a customized configuration file. As a result, software developers might choose to place the previous configuration file contents in a file called .rpmsave. Then a system administrator can review the .rpmsave file and determine which of the previous settings should be incorporated into the primary configuration file.

Another technique is for the software developers to use a .rpmnew file, as described in the previous section.

Repository Configuration Files

Repository configuration files, discussed in Chapter 6, are an integral component of package management. The Linux+ XK0-005 exam lists these topics in different exam categories, so the following section headings have been preserved to inform you where to go to find details about these topics.

/etc/apt.conf

See the “APT” section in Chapter 6.

/etc/yum.conf

See the “YUM” section in Chapter 6.

/etc/dnf/dnf.conf

See the “DNF” section in Chapter 6.

/etc/yum.repo.d

See the “YUM” section in Chapter 6.

/etc/apt/sources.list.d

See the “APT” section in Chapter 6.