Linux Basics of Centos7

Linux系统简介及安装

First, Rhel7/centos7 new features:
Identity Management
Kerberos's cross-platform trust mechanism: Kerberos is fully compatible with the Microsoft Active Directory, enabling full use of Active Directory authentication.
REALMD: This feature simplifies the configuration of Rhel into the Microsoft Active Directory and supports Autodiscover domain information.
Rhel 7 adds two key new features that improve the way Rhel works with AD. A cross-domain trust (Cross-realm trusts) is now established between RHEL 7 and AD, so ad users can access resources without logging on to the Linux side. Another ad-related feature added by RHEL 7 is REALMD, which automates querying and adding DNS information for AD (or other Red Hat authentication services).
2. Performance management
Performance AIDS: RHEL7 provides a new framework and a new general-purpose graphical interface for XXX to assist in management. System bottlenecks can be collected and analyzed.
Tuning and Tuning Configuration: RHEL7 provides dynamic tuning solutions to address system performance bottlenecks. System administrators can also manually modify the system presets to achieve the tuning effect
3. Virtualization
Enhanced RHEL7 Virtual machine: Fully compatible with Vmwarevshpere architecture, RHEL7 comes with open Vmtool, 3D graphics driver and OpenGLX11 support. Makes RHEL7 easier to deploy on VMware platforms. RHEL 7 also supports fast communication between vmware,esxi.
Virtual I/O: Provides the interface for invoking the underlying PCI device for each virtual machine, enabling kernel-level isolation. Improved machine security and compatibility virtual machine USB3.0 interface support
QCOW2 format file-based snapshots support nested virtualization support, can be installed in KVM configuration OpenStack strengthens technical support for VMware, with Open-vm-tools replacement vm-tools to support the hottest technology docker.
Docker is based on the current popular Application virtualization technology. Applications are packaged in Docker and completely isolated from the system and other applications, so they can be migrated between systems and run properly.
4. File system
RHEL7 selects XFS as its default file system. RHEL7.0 The default use of XFS when installing, not to say that the original Ext file system is no longer used, RHEL 7 is still supporting EXT4. Instead, the Ext file system has become more and more inadequate in the face of future explosive-growth data volumes. The XFS file system is full of big data, with a single file system that can support up to 8EB size, a single file size of up to 16T, and a rich logging system that is a powerful file system for big data storage. XFS is a highly scalable, high-performance file system. is also the default file system for RHEL7/CENTOS7. The XFS file system can be backed up and restored through tools Xfsdump and Xfsrestore.
5. Network Management
Added network management interface NMCLI
6. Service Management
Invoking a service script using Systemctl
The RHEL7 uses SYSTEMD instead of the original SYSV, which is used by SYSTEMD to manage the services in the system. SYSTEMD defines the way in which service and system processes are managed in a completely different manner from the original SYSV init process. Enables services in the system to automatically resolve dependencies between services, and can support the parallel start of services! In other words, RHEL7.0 is faster and more stable than the original SYSV operating system, and can also be perfectly supported docker!
7. RHEL7 Desktop
Use the latest Gnome 3 as the default desktop environment, using the latest KDE 4.10 as an alternative desktop environment.
Second, RHEL7 installation
1, production server if it is large memory (4G or more memory), it is recommended to install the 64-bit version.
After starting the load, such as:

Parameter description:
Install Red Hat Enterprise Linux 7.0 Installation RHEL7 system
Test this media & install Red Hat Enterprise Linux 7.0 testing installation media and installing the RHEL7 system (as opposed to RHEL6, advance the detection media to the initial installation page)
Troubleshooting Troubleshooting
2, select troubleshooting, you can see from the following interface:

Parameter explanation:
Installing the basic graphics mode
Installing the Rescue system
Memory test
Booting from a local drive
Back to Menu
Back to menu, select the first item install Red Hat Enterprise Linux 7.0 Press ENTER.
System start installation See:
Installation process language selection, the official production server is recommended to install English version, here to keep the default English click Next.

3. Click Continue
Go to the Installation Summary page, from this page three large blocks are displayed:
LOCALIZATION: Localization: You can configure the time zone, keyboard settings, and language below here.
Software: Software: Under software can go to installation source and custom software installation, default system selection minimized installation
System: Systems: Installing target devices and network configuration

4, click on accept changes, go back to the Installation Summary page, click on the Begin installation, enter the following interface:

5, select the user settings root password, set the root account password.
6, after the installation is complete, click Reboot restart
After reboot, go to the initial installation interface, configure the license and registration settings.
After the system is initialized for the first time, it enters the boot interface

The first is the normal boot system, and the second is to restore the boot system.
1), system default encoding settings file, changed from/etc/sysconfig/i18n to/etc/locale.conf the file master defines your current system locale variable settings, here is lang= "en_US. UTF-8 ", the system presets those language support.
2), Common command installation: Check the anaconda-ks.cfg to determine if the base software group is installed

If the base software group is not installed, some general commands, such as ifconfig, cannot be used. You can install the Base software group using Yum Groupinstall base.
Iii. rhel7 default RunLevel and terminal resolution modifications
rhel7.0 made a lot of big changes, open inittab look down

Inittab is no longer used when using SYSTEMD.
/etc/inittab This file is no longer in use, SYSTEMD is an init program for Linux and can be used as an alternative to sysvinit and Upstat.
SYSTEMD uses a more liberal target concept than the Sysvinit run level as an alternative
Third Run Level: Multi-user.target
V Run Level: graphical.target
The former is a symbolic link pointing to the back target
Runlevel3.target-Multi-user.target
Runlevel5.target-Graphical.target

To modify the boot default runlevel:
The default level is converted to 3 (text mode)
Ln-sf/lib/systemd/system/multi-user.target/etc/systemd/system/default.target
Or the default level is converted to 5 (graphics mode)
Ln-sf/lib/systemd/system/graphical.target/etc/systemd/system/default.target
Restart: reboot
How to implement RHEL7 graphical interface automatic login:
First find the/etc/gdm/custom.conf file
Then add the following in the custom.conf file under daemon:
Automaticloginenable=true
Automaticlogin=root

Linux Basics of Centos7