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  • Information for "Red Hat Enterprise Linux 6 Essentials" - Techotopia
    bytes 22 607 Page ID 2058 Page content language English en Page content model wikitext Indexing by robots Allowed Number of redirects to this page 1 Counted as a content page Yes Page protection Edit Allow all users infinite Move Allow all users infinite Edit history Page creator Neil Talk contribs Date of page creation 19 35 18 November 2010 Latest editor Neil Talk contribs Date of latest edit 21

    Original URL path: http://www.techotopia.com/index.php?title=Red_Hat_Enterprise_Linux_6_Essentials&action=info (2016-02-13)
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  • About CentOS 6 Essentials - Techotopia
    another Linux distribution Arguably one of the most highly regarded and widely used enterprise Linux distributions available today is Red Hat Enterprise Linux 6 RHEL 6 It is considered to be amongst the most stable and reliable operating systems and is backed by the considerable resources and technical skills of Red Hat Inc Red Hat Enterprise Linux is also an open source product meaning that anyone can access the source code to the operating system and modify it as they see fit Whilst the source code to RHEL is freely available RHEL is not free of charge In order to get a binary copy of this operating system you have to purchase it as part of a service agreement that includes technical support CentOS 6 is 100 compatible with Red Hat Enterprise Linux 6 In fact CentOS 6 is essentially Red Hat Enterprise Linux 6 with the Red Hat branding and logos removed CentOS is available for free so you get the power and stability of Red Hat Enterprise Linux without having to purchase it Of course CentOS lacks the dedicated and guaranteed technical support that you get by buying a Red Hat subscription so if you plan to deploy Linux in a mission critical environment where any level of downtime is unacceptable then the Red Hat service is unquestionably worth the money That said CentOS is backed by a skilled and active community and I have yet to encounter a problem with CentOS that could not be resolved with the help of the extremely responsive and helpful experts who participate on the CentOS forums CentOS 6 Essentials is designed to provide detailed information on the use and administration of the CentOS 6 x Linux distribution For beginners the book covers the basics of configuring the desktop environment resolving screen

    Original URL path: http://www.techotopia.com/index.php/About_CentOS_6_Essentials (2016-02-13)
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  • Installing CentOS 6 on a Clean Disk Drive - Techotopia
    make a selection with the Enter key After a short delay the first screen of the graphical installer will appear Navigate through the next few pages to configure your preferred language keyboard type and storage devices unless you plan to use a Storage Area Network device the Basic option is recommended If the installer detects that the target disk needs to be initialized a dialog will appear seeking confirmation When prompted enter a suitable host name for the CentOS 6 installation This is the name by which the system will be identified on the network to which it is attached Additional network configuration options may be modified by clicking on the Configure Network button selecting a network interface and clicking on the Edit button Timezone and the Root Password Subsequent screens will request information about Timezone and the root password of the system On the Timezone screen make a selection corresponding to your geographical location The option is also provided to use UTC which automatically adjusts the time to account for daylight savings time If the computer on which CentOS 6 is being installed also runs another operating system which already uses UTC such as Windows leave this option unselected On the next screen enter a password for the root account on the system The root or super user account is a special user that has administrative privileges on the system Whilst you will generally use your own account to log into the system you will need to gain root privileges in order to configure the system and to perform other administrative tasks The installer will subsequently move on to the disk partitioning screen Partitioning a Disk for CentOS 6 When you reach the disk partitioning phase of the installation the installer will present a screen similar to the one illustrated in the following figure A number of options are provided for allocating space for the installation of CentOS 6 Use All Space The entire disk drive will be assigned to the CentOS 6 operating system installation Any pre existing partitions together with any existing operating systems and associated data files contained therein will be deleted to make room for CentOS This option should only be used if you are absolutely sure you no longer need anything that is currently stored on that disk or have already backed up all user files Replace existing Linux System s If the drive was previously configured to support a Windows Linux dual boot environment or was devoted entirely to another Linux installation this option may be selected to instruct the installer to delete the pre existing Linux partition and replace it with CentOS 6 Once again it is important to backup any user data that may still be needed Shrink Current system Allows an existing partition to be reduced in size to make room on the drive for the CentOS 6 installation More details on this option are provided in a later chapter entitled Installing CentOS 6 with Windows in Dual Boot Environment

    Original URL path: http://www.techotopia.com/index.php/Installing_CentOS_6_on_a_Clean_Disk_Drive (2016-02-13)
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  • Performing a CentOS 6 Network Installation - Techotopia
    achieved using the mount loopback interface mount o loop rhel6 image iso path to mount point In this case path to mount point is replaced by the full path to the location where the RHEL 6 installation image is to be mounted such that it can be accessed via the chosen network installation method For example in the case of an HTTP based installation the chosen mount point might be var www html rhel6 Note that the specified mount point directory must already exist before executing this command Obtaining a Network Boot Image Once the remote server is configured with a copy of the RHEL 6 installation image the next step is to plan how the installation process will be initiated on the target system Clearly we will still need to be able to boot from something locally to start the installation The best option is to download the Network Install image from a CentOS mirror server at http mirror centos org centos 6 isos The file name containing this image is usually adopts the following format CentOS version architecture netinstall iso For example the 32 bit installation image for CentOS 6 2 is named CentOS 6 2 i386 netinstall iso This image is approximately 170 Mb in size and may be burned to a CDROM DVD or USB flash drive Writing the Boot Image to a USB Flash Drive Once the network installation ISO image has been downloaded from the CentOS web site it may optionally be burned onto a USB flash drive and then used to boot the system on which the network installation is to be performed This task is best performed on another Linux system using the dd command to directly write the ISO image to the flash drive Begin by inserting the USB flash drive into an appropriate port on the Linux system and wait for the system to detect the device and mount it Identify the device name assigned to the drive using the mount command in a terminal window and then unmount the media Assuming for the sake of an example that the mount command indicated the USB drive was assigned to device file dev sdb the following command would be used to write the ISO image to the drive dd if path to iso image of dev sdb Once the image has been written to the drive take it to the target system modify the BIOS boot settings to ensure that the system will boot from a USB device prior to any other storage devices and reboot the system Configuring the Network Installation When the network installer image has booted press the Esc key on the boot menu screen enter the following command at the boot prompt and press the enter key linux askmethod A sequence of screens will subsequently appear providing the opportunity to select a language and keyboard type Once these settings have been defined a screen will appear requesting the location of the installation media Depending on the method

    Original URL path: http://www.techotopia.com/index.php/Performing_a_CentOS_6_Network_Installation (2016-02-13)
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  • Installing CentOS 6 with Windows in a Dual Boot Environment - Techotopia
    not shrink the partition to the full extent available For the purposes of this example therefore we will shrink the partition to 10000MB Before performing the live resize it is best to run through a simulation in order to identify any potential problems before permanent changes are made To do this run ntfsresize with the no action option root livecd ntfsresize no action b size 10000M dev sda1 ntfsresize v1 13 1 libntfs 9 0 0 Device name dev sda1 NTFS volume version 3 1 Cluster size 4096 bytes Current volume size 21459722752 bytes 21460 MB Current device size 21459723264 bytes 21460 MB New volume size 9999995392 bytes 10000 MB Checking filesystem consistency 100 00 percent completed Accounting clusters Space in use 2945 MB 13 7 Collecting resizing constraints Needed relocations 45 1 MB Schedule chkdsk for NTFS consistency check at Windows boot time Resetting LogFile this might take a while Relocating needed data 100 00 percent completed Updating BadClust file Updating Bitmap file Updating Boot record The read only test run ended successfully Assuming the read only test runs successfully the actual resize can be performed by running the same command but this time without the no action option root livecd ntfsresize b size 10000M dev sda1 ntfsresize v1 13 1 libntfs 9 0 0 Device name dev sda1 NTFS volume version 3 1 Cluster size 4096 bytes Current volume size 21459722752 bytes 21460 MB Current device size 21459723264 bytes 21460 MB New volume size 9999995392 bytes 10000 MB Checking filesystem consistency 100 00 percent completed Accounting clusters Space in use 2945 MB 13 7 Collecting resizing constraints Needed relocations 45 1 MB WARNING Every sanity check passed and only the dangerous operations left Make sure that important data has been backed up Power outage or computer crash may result major data loss Are you sure you want to proceed y n y Schedule chkdsk for NTFS consistency check at Windows boot time Resetting LogFile this might take a while Relocating needed data 100 00 percent completed Updating BadClust file Updating Bitmap file Updating Boot record Syncing device Successfully resized NTFS on device dev sda1 You can go on to shrink the device for example with Linux fdisk IMPORTANT When recreating the partition make sure that you 1 create it at the same disk sector use sector as the unit 2 create it with the same partition type usually 7 HPFS NTFS 3 do not make it smaller than the new NTFS filesystem size 4 set the bootable flag for the partition if it existed before Otherwise you won t be able to access NTFS or can t boot from the disk If you make a mistake and don t have a partition table backup then you can recover the partition table by TestDisk or Parted s rescue mode At this point we have reduced the size of the NTFS partition but the partition does not yet know we have done so If for example we use fdisk to tell us about the partition the partition table information still indicates the original size root livecd fdisk l Disk dev sda 21 5 GB 21474836480 bytes 255 heads 63 sectors track 2610 cylinders Units cylinders of 16065 512 8225280 bytes Sector size logical physical 512 bytes 512 bytes I O size minimum optimal 512 bytes 512 bytes Disk identifier 0x8f6a8f6a Device Boot Start End Blocks Id System dev sda1 1 2609 20956761 7 HPFS NTFS In order to address this we will have to delete the partition information and then recreate it with the new size information Before doing so make a note of the Start and Id values for the partition provided by the above fdisk command since yours will almost certainly differ from the example and we will need these when we recreate the partition Begin by starting fdisk with the name of the disk drive on which we are going to modify the partition table information root livecd fdisk dev sda At the command prompt delete the partition for the example this is partition 1 but may be different on your system Command m for help d Selected partition 1 Next we need to recreate the partition with the new size information keeping in mind that we reduced the partition to 10000MB Command m for help n Command action e extended p primary partition 1 4 p Partition number 1 4 1 First cylinder 1 2610 default 1 1 Last cylinder or size or sizeM or sizeK 1 2610 default 2610 10000M Next the Id of the partition needs to set to the original value as indicated by the fdisk l command in this case 7 to indicate the partition uses the Windows NTFS format Command m for help t Selected partition 1 Hex code type L to list codes 7 Changed system type of partition 1 to 7 HPFS NTFS Finally we need to make sure the partition is still bootable Command m for help p Disk dev sda 21 5 GB 21474836480 bytes 255 heads 63 sectors track 2610 cylinders Units cylinders of 16065 512 8225280 bytes Sector size logical physical 512 bytes 512 bytes I O size minimum optimal 512 bytes 512 bytes Disk identifier 0x86008600 Device Boot Start End Blocks Id System dev sda1 1 1276 10249438 7 HPFS NTFS If the Boot column does not contain an asterisk then we need to make the partition bootable before we write the new configuration disk Command m for help a Partition number 1 4 1 Once again it is prudent to check the settings before proceeding Command m for help p Disk dev sda 21 5 GB 21474836480 bytes 255 heads 63 sectors track 2610 cylinders Units cylinders of 16065 512 8225280 bytes Sector size logical physical 512 bytes 512 bytes I O size minimum optimal 512 bytes 512 bytes Disk identifier 0x86008600 Device Boot Start End Blocks Id System dev sda1 1 1276 10249438 7 HPFS NTFS At this point none of the

    Original URL path: http://www.techotopia.com/index.php/Installing_CentOS_6_with_Windows_in_a_Dual_Boot_Environment (2016-02-13)
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  • Allocating a Windows Disk Partition to CentOS 6 - Techotopia
    size logical physical 512 bytes 512 bytes I O size minimum optimal 512 bytes 512 bytes Disk identifier 0x86008600 Device Boot Start End Blocks Id System dev sda1 63 20498939 10249438 7 HPFS NTFS dev sda2 20500480 21524479 512000 83 Linux dev sda3 21524480 41943039 10209280 8e Linux LVM Make a note of the end sector of the partition we will be deleting dev sda1 in this instance At the command prompt delete the Windows partition which is partition 1 on our example system Command m for help d Partition number 1 5 1 Command m for help Now that we have deleted the Windows partition we now need to create the new Linux partition in the vacated disk space The partition number must match the number of the partition removed in this case 1 and is going to be a primary partition It will also be necessary to enter the Start and End sectors of the partition In the case of the start sector accept the default value offered by fdisk Enter the end sector exactly as reported for the old partition fdisk will typically offer the correct values by default though it is wise to double check Command m for help n Command action e extended p primary partition 1 4 p Partition number 1 4 1 First sector 2048 41943039 default 2048 Using default value 2048 Last sector sectors or size K M G 2048 20500479 default 20500479 20498939 Having made these changes the next step is to check that the settings are correct Command m for help p Disk dev sda 21 5 GB 21474836480 bytes 255 heads 63 sectors track 2610 cylinders total 41943040 sectors Units sectors of 1 512 512 bytes Sector size logical physical 512 bytes 512 bytes I O size minimum optimal 512 bytes 512 bytes Disk identifier 0x86008600 Device Boot Start End Blocks Id System dev sda1 2048 20498939 10248446 83 Linux dev sda2 20500480 21524479 512000 83 Linux dev sda3 21524480 41943039 10209280 8e Linux LVM To commit the changes we now need to write the new partition information to disk and quit from the fdisk tool Command m for help w The partition table has been altered Calling ioctl to re read partition table WARNING Re reading the partition table failed with error 16 Device or resource busy The kernel still uses the old table The new table will be used at the next reboot or after you run partprobe 8 or kpartx 8 Syncing disks If you see a warning similar to the one indicated in the above output you will need to reboot your CentOS 6 system to be sure the new partition table information is picked up by the system kernel before proceeding Formatting the Unallocated Disk Partition In order to make the new partition suitable for use by CentOS 6 it needs to have a file system created on it The default file system type for the current release of CentOS 6 is ext4 Creation

    Original URL path: http://www.techotopia.com/index.php/Allocating_a_Windows_Disk_Partition_to_CentOS_6 (2016-02-13)
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  • Logging into the CentOS 6 GNOME Desktop - Techotopia
    you will most likely be presented with a Login Screen similar to the one shown in the following figure though the appearance and layout of the screen changes from one release of CentOS to the next This screen has a number of options and text fields that give the user some level of control over what happens next User Icons For each user with an account on the system an icon will appear next to their login name Clicking on this icon will begin the login process for that user and prompt for a password If the user is not listed for example the root user is not listed the Other button may be clicked to manually enter the user name Password This input field only appears after a user name has been selected from the list or typed into the Username field Once the password has been entered press the Enter key to initiate the login process The bottom of the screen contains a number of buttons The first button allows accessibility options such as screen reader magnification and keyboard settings to be configured Next is a power switch When clicked the button displays a menu containing the following power related options Restart Reboots the system If this option is selected the system will display a confirmation window verifying the system is to be restarted before doing so Shut Down Shuts the system down to its powered off state As with the Reboot option confirmation will be sought before the shutdown proceeds After a user has been selected the status bar along the bottom of the screen will change to display language and keyboard layout options Once valid login credentials have been provided CentOS 6 will initiate the login process and present the desktop As with the login screen

    Original URL path: http://www.techotopia.com/index.php/Logging_into_the_CentOS_6_GNOME_Desktop (2016-02-13)
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  • Configuring CentOS 6 GNOME Screen Resolution and Multiple Monitors - Techotopia
    step in configuring monitors involves setting the optimal screen resolution for both the monitor and the user CentOS 6 will generally do a good job of configuring these settings during installation but it may sometimes be necessary to modify these settings to obtain optimal results Assuming that CentOS 6 has successfully identified your display and graphics cards then it should be possible to increase the resolution to any value up to the maximum supported by the hardware using the Display Preferences screen accessed via the System Preferences Display menu option Using the Resolution menu select the desired screen resolution up to the maximum support by the hardware and click on the Apply button to commit the change Changing Display Orientation The Display Preferences dialog also provides the option to change the orientation of the desktop to match the orientation of the monitor This is achieved using the Rotation control This setting can be used to orient the desktop such that it will appear the right way up if the monitor is physically upside down or on its left or right side If you are feeling brave try changing the setting to upside down mode while your monitor is still the right way up Once the desktop is upside down revert to the Normal setting keeping in mind that the mouse will move up when you move it down left when you move it right and so on Configuring Multiple Monitors CentOS 6 supports multiple monitors connected to a single system allowing the desktop environment to be spread over more than one screen Multiple monitors are configured once again using the Display Preferences tool which may be accessed from the Desktop System Administration Display menu option If the system fails to detect an additional monitor click on the Detect Monitors button

    Original URL path: http://www.techotopia.com/index.php/Configuring_CentOS_6_GNOME_Screen_Resolution_and_Multiple_Monitors (2016-02-13)
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