Klae0010 at 00:46, 25 April 2012

2012-04-25T00:46:13Z

← Older revision	Revision as of 00:46, 25 April 2012
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		Here is a list of my wiki pages..

		Chapter 5 Linux


		Chapter 2 Linux
		Chapter 8 Linux
		Linux+ Giude to Certificationn, 3rd Ed.

		Service project for CCNA Security.

Klae0010: Blanked the page

2012-04-25T00:44:27Z

Blanked the page

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Klae0010: /* Wiki page credit */

2012-04-25T00:44:10Z

Wiki page credit

← Older revision		Revision as of 00:44, 25 April 2012
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	'''NOTE''' : ''all page numbers reference the CompTIA Linux+ Complete Study Guide by Roderick W. Smith ISBN 978-0-470-88845-2''		'''NOTE''' : ''all page numbers reference the CompTIA Linux+ Complete Study Guide by Roderick W. Smith ISBN 978-0-470-88845-2''

	~~==Wiki page credit==~~
	~~==== All info compiled, edited and coded by : Rob Klaers and Josh Motz ====~~

Klae0010: /* Changing runlevels on a running system */

2011-03-01T04:43:19Z

Changing runlevels on a running system

← Older revision		Revision as of 04:43, 1 March 2011
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	:: '''''2''' = is the current runlevel''		:: '''''2''' = is the current runlevel''
	=== Changing runlevels on a running system ===		=== Changing runlevels on a running system ===
	This can be done with the init (or telinit), shutdown, halt, reboot, or poweroff commands.		: This can be done with the init (or telinit), shutdown, halt, reboot, or poweroff commands.

			::''shutdown [option] [time] “[Message]” ''
			::: ex. '''shutdown –r +15''' “System going down for maintenance.”

			:Options
			:: '''-h''' ...Halt or power off the computer. (runlevel 0)
			:: '''-r''' ...Reboots the system. (runlevel 6)
			:: '''-c''' ...Cancels a scheduled shutdown. Time hh:mm
			:::'' Tells the computer when to run the shutdown command in a 24 hour format.''
			:: '''+ t''' ...t = time to shutdown in minutes.
			:: '''Message''' ...Adds a message at the end of the command

	== Runlevel Services (pg.243) ==		== Runlevel Services (pg.243) ==

Klae0010 at 04:37, 1 March 2011

2011-03-01T04:37:01Z

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Klae0010: /* Installing Boot Loaders */

2011-03-01T03:43:15Z

Installing Boot Loaders

← Older revision		Revision as of 03:43, 1 March 2011
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	== Installing Boot Loaders ==		== Installing Boot Loaders ==
	The master boot record (MBR) contains a partition table and a boot loader (aka boot manager). The boot loader is software which the BIOS reads and executes when the system begins to boot		:: The master boot record (MBR) contains a partition table and a boot loader (aka ''boot manager''). The boot loader is
			:: software which the BIOS reads and executes when the system begins to boot


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	::: Title		::: Title
	::: GRUB root		::: GRUB root
	::: Kernel Specification		::: Kernel Specification

	== Runlevels And Initialization Process ==		== Runlevels And Initialization Process ==

Klae0010: /* Locating and Interpreting Boot Messages */

2011-03-01T03:42:34Z

Locating and Interpreting Boot Messages

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	=== Locating and Interpreting Boot Messages ===		=== Locating and Interpreting Boot Messages ===
	: Use less and it’s search functions		: Use ''less'' and it’s search functions
	: Look for hardware type names		: Look for hardware type names
	: Look for hardware chipset names		: Look for hardware chipset names
	: Study output from a working system		: Study output from a working system


	== Installing Boot Loaders ==		== Installing Boot Loaders ==

Klae0010 at 03:36, 1 March 2011

2011-03-01T03:36:51Z

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Klae0010: Created page with "'''Chpt 5 Study Guide''' == Boot Process == ''System power > CPU looks for BIOS > CPU Runs Bios'' ::BIOS checks for new hardware, configure hardware, and looks for boot secto..."

2011-02-28T23:27:11Z

Created page with "'''Chpt 5 Study Guide''' == Boot Process == ''System power > CPU looks for BIOS > CPU Runs Bios'' ::BIOS checks for new hardware, configure hardware, and looks for boot secto..."

New page

'''Chpt 5 Study Guide'''

== Boot Process ==
''System power > CPU looks for BIOS > CPU Runs Bios''

::BIOS checks for new hardware, configure hardware, and looks for boot sector.This is when the BIOS finds the boot loader in
::the boot sector.Boot loader takes over from BIOS. If a multistage loader is available, a secondary loader is searched for.
::Finally, the boot loader finds the kernel, loads it into memory and then executes it. Once the LINUX kernel takes over, it then
::begins to initial devices, mounting root partition and other such tasks.The initial program is also started at this stage.It
::gets a process ID of 1 because it’s the first program run on the system.

=== Retrieving Information about the boot process ===
: Certain information about the Linux kernel and module log info can be found in the kernel ring buffer.
: This info is displayed during the boot process, but is shown too fast to be read.
: To access this info type the following command..
:: '''#dmesg | less'''
:: '''#dmesg > boot.messages'''

=== Locating and Interpreting Boot Messages ===
: Use less and it’s search functions
: Look for hardware type names
: Look for hardware chipset names
Study output from a working system

== Installing Boot Loaders ==
The master boot record (MBR) contains a partition table and a boot loader (aka boot manager). The boot loader is software which the BIOS reads and executes when the system begins to boot

=== Two main boot loaders for Linux ===
: '''LILO''' ''(Linux Loader)''
:: Once the default boot loader.
:: Slowly being overtaken by GRUB.
:: Small, and useful.

: '''GRUB''' ''(Grand Unified Boot Loader)''
:: Has taken over as default boot loader for many LINUX distributions
:: Offers more configurations than LILO

== LILO ==
Can be configured using the /etc/lilo.conf file.
This file is broken into two main sections :

=== Global options : ===

: Boot loader location
: Default stanza
: Boot prompt
: Boot timeout

=== Per-Image : ===
: Kept in sections known as stanzas.
:: Can also be further seperated depending on if they’re for a kernel or OS.
:
Some Per-Image Options include :
: Linux Boot Image
: Non-Linux Boot Partition
: OS Label
: RAM Disk

== GRUB ==
: GRUB has some ‘quirks’
:: Unlike Linux, GRUB numbers drives.
:: Instead of /dev/hda .. It would be /dev/hd0
::: Doesn’t distinguish between PATA, SATA, or SCSI drives.
:: GRUB also numbers partitions on a drive starting with 0, instead of 1
::: So partition 1 on drive 1 would look like this (hd0,0)
::: Floppy devices are referred to as (fd0)

: GLOBAL OPTIONS
: Default OS
: Timeout
: Background Graphic
: Per-Image Options
: Title
: GRUB root
: Kernel Specification

== Runlevels And Initialization Process ==
Linux relies on runlevels to determine which features are available.
Run levels are labels 0 thru 6. Each one being assigned to a set of services that should be active.
Understanding the purpose of runlevels makes for identifying services that are active easier.

== Checking runlevel ==
Generally done prior to changing or to check status if something isn’t working
This is done by inspecting the /etc/initab file with the less command or opening it in an editor.

== Managing Runlevels ==
Chkconfig
Lists the services and their runlevels.
Ex. Chkconfig –list
ntsysv
Used mainly on Red Hat
Interactive text tool
Use your arrow keys to select a service.

== Runlevels ==
: 0 – Transitional, Shuts down the system.
:: Should completely power down the system.
: 1, s, or S – Single user mode.
:: Used for low-level system maintenance impaired by normal system operation.
: 2 – Full muti-user mode with a graphical login.
:: Used on Debian
: 3 – Full multi-user mode with a console login.
:: Used on Fedora, Mandriva, Red Hat, and most other distributions.
: 4 – Undefined by default
:: Used for customization
: 5 – Same as runlevel 3 with the addition of having X run with XDM (graphical) login.
: 6 – Used to reboot the system.
:: Also a transitional runlevel.

== Determining Current Runlevel ==
Once system is up and running runlevel info can be checked by entering :
# runlevel
N 2

The first character is the previous runlevel.
N = system hasn’t changed runlevel since starting
2 = is the current runlevel

== Changing runlevels on a running system ==
This can be done with the init (or telinit), shutdown, halt, reboot, or poweroff commands.

== Runlevel Services ==

Two main ways to affect what programs run as you enter a new runlevel.

/etc/inittab
SysV

== /etc/inittab ==
Id:runlevels:action:process
Identification code
Consists of a sequence of 1-4 characters to identify its function
Applicable runlevels
List of runlevels for which this entry applies.
Action to be taken
Tells init how to treat the function.
Process to run
Process to run for this entry.
Includes options and arguments

== System V (SysV) ==
Controls what startup scrips start or stop services depending on the parameters that are passed.
S
rc passes the start parameter to all scrips that begin with the letter S.
K
rc passes the stop services to all scrips that begin with the letter K.

== Vi ==

First full-screen text editor built for linux.
Used for a emergency recovery situations.
Small and simple
Can fit on a floppy disk.
3 modes of operation

=== Vi Modes ===

; '''Command mode'''
: Accepts single letter commands.
: '''i''' and a = enter insert mode
: '''o''' =opens a line below the current one.

; '''Ex mode'''
: Used to manipulate and save current flies and run outside programs.
: Type :x from command mode to enter Ex mode.
: '''x''' = the command you want to use.
: Automatically returns to command mode when finished.
: Also referred to as colon commands

; '''Insert mode'''
: Used to enter text.
: Most input results in text appearing on the screen.
: Use '''Esc''' key to return to command mode.

=== Using Vi ===
Use vi [file name] to launch Vi
: Ex. '''vi lilo.conf'''
:: Have to be in the directory that is holding the file.

==== Command mode ====
: The up, down, left, and right keys are used to move the curser.
: '''yy''' and '''dd''' to ''yank (copy)'' text to a buffer.
: '''dd''' also ''deletes'' the lines that are yanked.
: Extentions of the '''y''' and '''d''' commands.
: '''p''' is used to paste the contents of the buffer.

==== Ex mode ====
: ''':w''' saves the file.
: ''':q''' quits vi
:: Only works if the changes have been saved or used with '''!'''. (Ex. :q!)
: ''':e''' edits a new file
:: Ex. ''':e /etc/inittab''' loads /etc/inittab for editing.
:: Only works if existing file has been saved or used with an !. (Ex. :e! /etc/inittab)
: ''':![command]''' executes the external command.
:: Ex. :!ls executes the list command.

==== Insert mode ====
: In command mode you can use '''R''', '''i''', and '''a''' to enter insert mode.
:: '''R''' - Enters text replacement.
::: Replace appears in the status line.
:: '''i''' - Enters text insertion
:: '''a''' - Enters text insertion but advances the curser one space.
::: Can be useful at the end of a line
:: '''~''' - Used to change the case of a single word.
:: '''u''' - Undo’s any changes
:: '''o''' - Opens any text.
::: It inserts a new line below the current line while entering insert mode on that line.
:: '''G''' - Goes to a specific line.
:: ''':%s/[oringinal string]/[replacement]'''
::: Replaces all occurrences of one string with another.

User:Klae0010 - Revision history

Klae0010 at 00:46, 25 April 2012

Klae0010: Blanked the page

Klae0010: /* Wiki page credit */

Klae0010: /* Changing runlevels on a running system */

Klae0010 at 04:37, 1 March 2011

Klae0010: /* Installing Boot Loaders */

Klae0010: /* Locating and Interpreting Boot Messages */

Klae0010 at 03:36, 1 March 2011

Klae0010: Created page with "'''Chpt 5 Study Guide''' == Boot Process == ''System power > CPU looks for BIOS > CPU Runs Bios'' ::BIOS checks for new hardware, configure hardware, and looks for boot secto..."