Chapter 1. Getting Started

Accurate time keeping is important for a number of reasons. In Red Hat Enterprise Linux 7, time keeping is ensured by the NTP protocol, which is implemented by a daemon running in user space. The user space daemon updates the system clock running in the kernel. The system clock can keep time by using various clock sources.

Red Hat Enterprise Linux 7 uses the following daemons to implement NTP:

If you want to use ntpd instead of default chronyd, you need to disable chronyd, install, enable and configure ntpd as shown in Chapter 19, Configuring NTP Using ntpd.

Displaying the Current Date and Time

To display the current date and time, use one of the following commands:

~]$ date

~]$ timedatectl

Note that the timedatectl command provides more verbose output, including universal time, currently used time zone, the status of the Network Time Protocol (NTP) configuration, and some additional information.

For more information on configuring the date and time, see Chapter 3, Configuring the Date and Time.

System-wide locale settings are stored in the /etc/locale.conf file, which is read at early boot by the systemd daemon. The locale settings configured in /etc/locale.conf are inherited by every service or user, unless individual programs or individual users override them.

Basic tasks to handle the system locales:

For more information on configuring the system locale, see Chapter 2, System Locale and Keyboard Configuration.

The keyboard layout settings control the layout used on the text console and graphical user interfaces.

Basic tasks to handle the keyboard layout include:

For more information on configuring the keyboard layout, see Chapter 2, System Locale and Keyboard Configuration.

Ways to configure network access during the installation proces:

When the system boots for the first time after the installation has finished, any network interfaces which you configured during the installation are automatically activated.

For detailed information on configuration of network access during installation process, see Red Hat Enterprise Linux 7 Installation Guide.

Run the following commands as the root user to manage network connections using the nmcli utility.

To create a new connection:

~]# nmcli con add type type of the connection "con-name" connection name ifname ifname interface-name the name of the interface ipv4 address ipv4 address gw4 address gateway address

To modify the existing connection:

~]# nmcli con mod "con-name"

To display all connections:

~]# nmcli con show

To display the active connection:

~]# nmcli con show --active

To display all configuration settings of a particular connection:

~]# nmcli con show "con-name"

For more information on the nmcli command-line utility, see Red Hat Enterprise Linux 7 Networking Guide.

The NetworkManager text user interface (TUI) utility, nmtui, provides a text interface to configure networking by controlling NetworkManager.

For more information about installing and using the nmtui text interface tool, see Red Hat Enterprise Linux 7 Networking Guide.

In web console, the Networking menu enables you:

Figure 1.1. Managing Networking in web console

The products installed on Red Hat Enterprise Linux 7, including the operating system itself, are covered by subscriptions.

A subscription to Red Hat Content Delivery Network is used to track:

This section provides a brief summary of registering Red Hat Enterprise Linux 7 during the installation process. If your operating system is not registered after the installation, you can find what might have been missed during the installation by reading through this section. For detailed information, consult Red Hat Enterprise Linux 7 Installation Guide.

Basically, there are two ways to register the system during the installation:

If you have not registered your system during installation process, you can do it afterwards by applying the following procedure. Note that all commands in this procedure need to be performed as the root user.

For more information on registration of your system and attachment of the Red Hat Content Delivery Network subscriptions, see Chapter 7, Registering the System and Managing Subscriptions.

To access the Extended Update Support (EUS) content, register your system as follows:

For currently supported EUS releases, see Extended Update Support Add-on.

The following procedure describes how to register a system and utilize the E4S content.

The Red Hat Content Delivery Network subscription service provides a mechanism to handle Red Hat software inventory and enables you to install additional software or update already installed packages. You can start installing software once you have registered your system and attached a subscription, as described in Section 1.3, “The Basics of Registering the System and Managing Subscriptions”.

All software on a Red Hat Enterprise Linux system is divided into RPM packages, which are stored in particular repositories. When a system is subscribed to the Red Hat Content Delivery Network, a repository file is created in the /etc/yum.repos.d/ directory.

Use the yum utility to manage package operations:

For information on basic tasks related to the installation of software, see Section 1.4.3, “Managing Basic Software Installation Tasks with Subscription Manager and Yum”. For further information on managing software repositories, see Section 7.2, “Managing Software Repositories”. For detailed information on using the yum utility, see Chapter 9, Yum.

The most basic software-installation tasks that you might need after the operating system has been installed include:

You can determine services that are enabled or disabled at boot time already during the installation process, or you can enable or disable a service on an installed operating system.

To create the list of services enabled or disabled at boot time during the installation process, use the services option in the Kickstart file:

services [--disabled=list] [--enabled=list]

To enable or disable a service on an already installed operating system:

~]# systemctl enableservice_name

~]# systemctl disableservice_name

For further details, see Section 10.2, “Managing System Services”.

In web console, select Services to manage systemd targets, services, sockets, timers and paths. There you can check their status, start or stop them, enable or disable them.

Figure 1.2. Managing Services in web console

For more information on systemd, see Chapter 10, Managing Services with systemd.

The most basic tasks to manage user accounts and groups, and the appropriate command-line tools, include:

For detailed information on managing users and groups, see Chapter 4, Managing Users and Groups.

If you want to use graphical user interface to manage users and groups, see Section 4.2, “Managing Users in a Graphical Environment”.

To manage accounts in web console, select the Accounts menu.

Figure 1.4. Managing User Accounts in web console

In case of a system crash, you can use the Kernel crash dump mechanism called kdump that enables you to save the content of the system’s memory for later analysis. The kdump mechanism relies on the kexec system call, which can be used to boot a Linux kernel from the context of another kernel, bypass BIOS, and preserve the contents of the first kernel’s memory that would otherwise be lost.

When kernel crash occurs, kdump uses kexec to boot into a second kernel (a capture kernel), which resides in a reserved part of the system memory that is inaccessible to the first kernel. The second kernel captures the contents of the crashed kernel’s memory (a crash dump) and saves it.

During the installation, enablement and activation of kdump can be done either in the Anaconda installer or using the %addon com_redhat_kdump command in the Kickstart file.

For more information, see the appropriate source according to the installation method:

To ensure that kdump is installed and to configure it:

In web console, select Kernel dump to verify:

Figure 1.5. Configuring kdump in web console

For more information on kdump, see Red Hat Enterprise Linux 7 Kernel Crash Dump Guide.

ReaR is a disaster recovery and system migration utility which enables you to create the complete rescue system. By default, this rescue system restores only the storage layout and the boot loader, but not the actual user and system files.

Additionally, certain backup software enables you to integrate ReaR for disaster recovery.

ReaR enables to perform the following tasks:

To install ReaR, enter as the root user:

~]# yum install rear

Use the settings in the /etc/rear/local.conf file to configure ReaR.

For further information see, Section 27.1, “Basic ReaR Usage”.

~]# rear mkrescue

For further information on creating the rescue system with ReaR, see Section 27.1.3, “Creating a Rescue System”.

ReaR contains a fully-integrated built-in, or internal, backup method called NETFS.

To make ReaR use its internal backup method, add these lines to the /etc/rear/local.conf file:

BACKUP=NETFS
BACKUP_URL=backup location

You can also configure ReaR to keep the previous backup archives when the new ones are created by adding the following line to /etc/rear/local.conf:

NETFS_KEEP_OLD_BACKUP_COPY=y

To make the backups incremental, meaning that only the changed files are backed up on each run, add this line to /etc/rear/local.conf:

BACKUP_TYPE=incremental

For detailed information about using the ReaR NETFS internal backup method, see Section 27.2.1, “The Built-in Backup Method”.

For information on supported external backup methods and unsupported backup methods, see Section 27.2.2, “Supported Backup Methods” and Section 27.2.3, “Unsupported Backup Methods”.

The syslog messages are handled by two services:

The syslog messages are stored in various subdirectories under the /var/log directory according to what kind of messages and logs they contain:

By using the Red Hat Customer Portal you can:

To access the Red Hat Customer Portal, go to https://access.redhat.com..

To work with Red Hat Customer Portal services related to Red Hat support, you can use:

~]$ redhat-support-tool
Welcome to the Red Hat Support Tool.
Command (? for help):

Command (? for help): ?

The SOS report collects configuration details, system information and diagnostic information from a Red Hat Enterprise Linux system. Attach the report when you open a support case.

Note that the SOS report is provided in the sos package, which is not installed with the default minimal installation of Red Hat Enterprise Linux 7.

To install the sos package:

~]# yum install sos

To generate an SOS report:

~]# sosreport

To attach the sos report to your support case, see the Red Hat Knowledgebase article How can I attach a file to a Red Hat support case?. Note that you will be prompted to enter the number of the support case, when attaching the sos report.

For more information on SOS report, see the Red Hat Knowledgebase article What is a sosreport and how to create one in Red Hat Enterprise Linux 4.6 and later?.