Agenda
Administrative Issues
Link of the Week
This Week’s Expected Outcomes
Review for midterm exam
Moving around in UNIX
Break-Out Problems
Upcoming Deadlines
Hands-on Information
Lab Assistance, Questions, and Answers
Announcements
Announcements
Sign up for your open source topic if you have not
done so yet.
Final exam December 10 (week 14) and 17 (week
15).
Link of the week
http://en.wikipedia.org/wiki/Firmware
This Web site contains information on:
- Evolved firmware uses
- Firmware and device drivers
- Firmware support challenges in PCs
- Firmware hacking
http://www.driverfix.com/driverdetective.php?t=Firmware
DiverDetective
Download driver updates automatically and safely. This
software utility will keep your system up-to-date by
automatically retrieving the latest drivers from your
hardware’s manufacturer.
Link of the week
Firmware is a computer program that is
embedded in the hardware device. Firmware can be
stored in flash memory or as a binary image file that
can be uploaded onto existing hardware by a user. In
summary, firmware is a combination of hardware and
software.
Firmware applications include the following:
- BIOS found in IBM-compatible PCs.
- Open Firmware, used in computers
marketed by Sun Microsystems and
Apple Computers.
- Computer peripherals
- The iPod’s control menus.
- Automobiles with on-board computers/sensors
- Cisco IOS
This Week’s Expected Outcomes
Upon successful completion of this
module, the student will be able to:
/etc/fstab file
fsck utility
/proc directories
ASCII and EBCDIC Character set
CMOS
BIOS
Linux boot-up procedure (System 5)
Red Hat Enterprise Release 6.0 boot-up procedure
(Upstart)
Kernel
Firmware
CPU
Memory
Devices
UNIX Operating System
Field description of /etc/fstab
1st field describes the block special device or remote
file system or device name to be mounted.
2nd field describes the mount point for the file system.
3rd field describes the type of file system.
4th field describes the mount options associated with
the file system.
5th field describes which file systems will need to be
dumped by the dump() command.
6th field is used by fsck to determine the order in
which the file systems are checked at boot time.
UNIX Operating System
File System Integrity Checks
File systems are usually mounted
read-only. This makes it possible to check
the file system while it is mounted; it is
not a good idea to check a file system that
is mounted read-write.
UNIX Operating System
Fsck Command
The fsck utility checks the file system’s
consistency, reports any problems it finds, and
optionally repairs them.
On many legacy systems such as BSD
style systems, the fsck command is invoked
automatically on boots and reboots.
Format: fsck [options] device
UNIX Operating System
Fsck Phases
Fsck checks the file system in a series of 5
pages and checks a specific functionality of
file system in each phase.
Phase 1 – Check Blocks and Sizes
Phase 2 – Check Pathnames
Phase 3 – Check Connectivity
Phase 4 – Check Reference Counts
Phase 5 – Check Cylinder Groups
UNIX Operating System
Fsck Phases
If the superblock is corrupted the file
system still can be repaired using alternate
superblocks created while making a new file
system.
The first alternate superblock number is 32
and other superblock numbers can be found
using the following command:
newfs -N /dev/rdsk/c0t0d0s6
UNIX Operating System
/proc/filesystems
The /proc/filesystems is a file used to
detect file systems supported by the running
kernel. If a file system is listed, you will be
able to mount it. This text listing of the file
system is compiled into the kernel.
The “nodev” string in the first column means
that file system does not require a block device
to be mounted, it’s called a virtual file system.
UNIX Operating System
/proc/filesystems
It is a special file system in UNIX-like
systems that presents information about
processes and other system information in a
hierarchical file like structure, providing a
more convenient and standardized method for
dynamically accessing process data held in the
kernel than traditional tracing methods or
direct access to kernel memory. Typically, it is
mapped to a mount point named /proc at boot
time.
UNIX Operating System
/proc/filesystems
The /proc/filesystems file provides a
method of communication between
kernel space and user space.
UNIX Operating System
/proc/filesystems
Is a file used to detect filesystems
supported by running kernel. You can
quickly run grep or the cat command to
display the list of all supported file
systems. Nodev indicates that the file
system is not associated with a physical
device such as /dev/sdb1. If you see ext3
or vfat, it means you will be able to
mount ext3 and vfat based file systems.
UNIX Operating System
/proc/filesystems
The Linux implementation of /proc also
clones that of Plan 9. Under Linux, /proc
includes a directory for each running process
(including kernel processes) at /proc/PID,
containing information about that process.
Plan 9 is an enhancement of the V8 Plan.
Rather than have just one file containing all
the information about a process, Plan 9
created a hierarchy of separate files to
provide those functions, and made /proc a
real part of the file system
UNIX Operating System
/proc/filesystems
/proc/PID/cmdline, which contains the command that
originally started the process.
/proc/PID/cwd, a symlink to the current working
directory of the process.
/proc/PID/environ, a file containing the names and
contents of the environment variables that affect the
process.
/proc/PID/exe, a symlink to the original executable
file, if it still exists (a process may continue running
after its original executable has been deleted or
replaced).
UNIX Operating System
/proc/filesystems
/proc/PID/fd, a directory containing a symbolic
link for each open file descriptor
/proc/PID/fdinfo, a directory containing files
which describe the position and flags for each
open file descriptor.
/proc/PID/maps, a text file containing
information about mapped files and blocks
(like heap and stack).
UNIX Operating System
/proc/filesystems
/proc/PID/mem, a binary file representing the
process's virtual memory, can only be accessed
by a ptrace'ing process.
/proc/PID/root, a symlink to the root path as
seen by the process. For most processes this
will be a link to / unless the process is running
in a chroot jail.
/proc/PID/status, a file containing basic
information about a process including its run
state and memory usage.
UNIX Operating System
/proc/filesystems
/proc/PID/task, is a directory
containing hard links to many tasks
that have been started by this (i.e.:
the parent) process.
UNIX Operating System
File Representation
A file format is a particular way to encode
information for storage in a computer file.
Disk drives or computer storage are represented in
bits. A computer must convert information to 0s and
1s and vice-versa.
A computer file format can be represented as
either a binary image or ASCII file.
ASCII is used on most PCs and Macintoshes.
EBCDIC (Extended Binary-Coded Decimal
Interchange Code is an IBM code for representing
characters as numbers. IBM uses EBCDIC widely on
their large computers.
UNIX Operating System
EBCDIC character set
EBCDIC is an 8 bit character
encoding used on IBM mainframes and
AS/400s.
Single byte EBCDIC takes up eight
bits, which are divided in two pieces. The
first four bits are called the zone and
represent the category of the character,
whereas the last four bits are called the
digit and identify the specific character.
UNIX Operating System
File Representation
Binary image files represent 256
different binary codes.
UNIX Operating System
In the past, binary image files use to be
able to represent more character codes than
ASCII because eight bit bytes were used,
whereas ASCII files used seven bits. Now
Extended ASCII uses eight bit bytes and can
represent 256 character
Executable software, mostly word
processing files and databases, spread sheets
and multimedia files are binary. However, text
and source program files as well as HTML and
XML files are ASCII.
UNIX Operating System
What does the CMOS do?
The CMOS memory stores information
your computer needs when it boots up, such as,
disk drive, keyboard type, configuration details
of the PCI Bus slots, and Video Interface
information. If the power to the CMOS memory
is lost, your computer will boot with the CMOS
defaults. In most cases, this will prevent use of
your disk drives until this information is
supplied.
UNIX Operating System
CMOS specifications
The information stored in the CMS
memory is battery backed up. The CMOS
memory is a 64 or 128 byte memory that is part
of the system clock chipset chips. The CMOS
memory is made from Complementary Metal
Oxide Semiconductor (CMOS). This material
can be backed up by battery, which requires a
very low current to keep the data in the memory
with the power turned off.
UNIX Operating System
How is the CMOS information used?
The CMOS information is required by your
computers Basis Input/Output System (BIOS). The
system BIOS is a 64K by 8 bit wide ROM mounted on
the motherboard. If the BIOS ROM were accessed
during normal operation the computer would be greatly
reduced. Instead, the information is copied to some
RAM where it can be accessed 32 or 64 bits at a time,
thus increasing the system performance. The
differences in access speed between RAM device and
ROM’s is approximately 3 times faster.
UNIX Operating System
How is the CMOS information used?
Read-only memory or ROM is a form of data
storage in computers and other electronic devices that
can not be easily altered or reprogrammed. RAM is
referred to as volatile memory and is lost when the
power is turned off whereas ROM in non-volatile and
the contents are retained even after the power is
switched off.
UNIX Operating System
How is the CMOS information used?
Random Access Memory (RAM) is a form of
data storage that can be accessed randomly at any time,
in any order and from any physical location in contrast
to other storage devices, such as hard drives, where the
physical location of the data determines the time taken
to retrieve it. RAM is measured in megabytes and the
speed is measured in nanoseconds and RAM chips can
read data faster than ROM.
UNIX Operating System
Role of system BIOS
It is to test the system, initialize some I/O
devices, recognize the hardware devices (basic
power test), and load the operating system.
Once, the operating system is loaded, the BIOS
works with the operating system to enable
access to the hardware devices. At this point,
the BIOS provide basic input/output services to
the operating system and applications.
UNIX Operating System
What is Unified Extensible Firmware
Interface (UEFI)?
UEFI is a specification defined
between the operating system and the
platform firmware. UEFI was developed to
replace the Basic I/O System firmware
interface system. The UEFI can support
remote diagnostics and repair of
computers, even without another operating
system.
UNIX Operating System
UEFI
UNIX Operating System
UEFI
UNIX Operating System
Initializing or Booting a System
1. CPU is pre-set to RESET mode
2. CPU pre-programmed to seek 0xfffffff0 address
location
3. BIOS reads MBR (Track 0, Sector 1)
4. First part of MBR contains the boot partition
table and executable code
5. Second part of the MBR is used to locate the
boot loader. It resides on the “active” partition
known as the Boot Sector.
6. Device drivers are loaded (initrd-2.4.20-8.img)
7. Kernel is invoked
8. Init process invoked
UNIX Operating System
Linux Boot Procedure
1. The system startup stage depends on the hardware
device that Linux is being booted on. Floppy
disk, CD-ROM, a partition on a hard disk, a
device on the network, or a USB flash memory
stick. Linux is usually booted from a hard disk.
2. After the system locates the boot device, the first
part of the boot loader is loaded into RAM and
executed. Normally, the first part of the boot
loader is less than 512 bytes and is responsible
for loading the second part of the boot loader.
UNIX Operating System
Linux Boot Procedure
3. The first 446 bytes are considered the primary boot
loader, which contains both executable code and
error message text.
4. The second sixty four bytes are the partition tables,
which contains a record for each of the four
partitions.
5. The last two bytes are the magic number which
serves as a validation check of the Master Boot
Record (MBR).
UNIX Operating System
Linux Boot Procedure
6. When the second part of the boot loader is
loaded into RAM and executed, a pop up
screen displays Linux and the optional initial
RAM being loaded into memory.
7. The second part of the boot loader is called the
kernel loader. After the boot images are loaded,
the second part of the boot loader passes
control to the kernel image. At this point, the
kernel is decompressed and initialized
UNIX Operating System
Linux Boot Procedure
8. The second part of the boot loader
checks the system hardware, lists
attached hardware devices, mounts the
root device, and loads the kernel
modules.
UNIX Operating System
What is the Master Boot Record (MBR)
It is a small program that is a special
type of boot sector that manages the boot
process. The MBR is not located in a
partition, but located at the beginning of
partitioned computer mass storage devices,
such as, fixed disks or removable devices.
The organization of the partition
table in the Master Boot Record sets the
boundaries for the maximum addressable
storage space of a disk to 2 TB (2exp32 x
512 bytes)
UNIX Operating System
Master Boot Record (MBR)
When a data storage device has been
partitioned with the MBR Partition Table
scheme the master boot record contains
the primary partition entries in its
partition table.
By convention, there are exactly four
primary partition table entries in the
MBR Partition Table scheme.
UNIX Operating System
Boot Loaders
The following /boot directory contains all the
important files which are required for successful
booting process:
Demonstrate: /boot
Red Hat Linux kernels
Kernel configuration files for Red Hat
Linux
Demonstrate: /boot/grub
The Linux Loader (LILO) is the combination of
parts one and two boot loaders. Because of some
disadvantages in the LILO loader, the GRand Unified
Bootloader (GRUB) has become more widely used.
UNIX Operating System
Boot loader
The role of the boot loader is to place
the operating system of the system in
memory.
In Linux, the most commonly used
boot-loading tool is LILO, the Linux
Loader. During the installation process,
Linux will generate LILO values and ask
you to verify them. At that point, you are
given the opportunity to insert additional
LILO options. Such options might be to
include more partitions, and identify the
operating system to be installed.
UNIX Operating System
Boot loader
First, what exactly is GRUB? GRUB is a
boot loader, which means it passes control of
the boot process from the Power-On Self Test
(POST) to the kernel of your GNU/Linux
distribution. GRUB works in a modular,
layered fashion so that any unneeded modules
are not loaded. Not only does this reduce
execution time, but it saves valuable resources
when running from removable media.
UNIX Operating System
Boot loader
GRUB optionally loads its
configuration file at run/boot time, so you
don’t have to type in commands manually
each time. However, the command-line
option is still available in case there is an
error in your configuration file.
UNIX Operating System
When a computer with Red Hat
Enterprise Linux is turned on, the
operating system is loaded into memory
by a special program called a boot loader.
A boot loader usually exists on the
system's primary hard drive (or other
media device) and has the sole
responsibility of loading the Linux kernel
with its required files or (in some cases)
other operating systems into memory.
UNIX Operating System
So why use GRUB when there are
other options out there? The beauty of
free software is that you have choices.
Alternatives to GRUB include LILO,
syslinux and isolinux. The benefit of
GRUB is that it will work with many
different types of boot devices, but
you only need to learn one set of menu
commands. In addition, GRUB can
work on other forms of bootable
storage, such as CD-R/W,
UNIX Operating System
With the release of Red Hat Enterprise
Linux (RHEL) 6, Red Hat will utilize the new
Upstart boot service. This service will replace
the System V init boot procedure that is based
on run levels directories that contained scripts
that all had to be started. Upstart is event
driven, so it contains scripts that are activated
on demand, which makes the boot process a
lot faster.
UNIX Operating System
In an attempt to simplify the
new concept, Upstart still utilizes
the services from the init process.
The /sbin/init, which is the mother
of all user services
UNIX Operating System
Init Process
Location: /sbin/init
First process to execute in user space
Executes: background
Process ID: 1 (one)
Parent Process ID: 0 (zero)
Owner: root
Highlight the relationship of the init process to all other
executing processes.
UNIX Operating System
Red Hat Enterprise Release 6.0 (Upstart)
Handles initialization by starting the most
fundamental services.
/etc/init/rcS.conf
Handles starting the individual runlevels
/etc/init/rc.conf
The following two areas specify how
terminals are to be handled.
/etc/init/tty.conf and /etc/init/serial.conf
There were some additional configuration
files included to the /etc/sysconfig/init file.
UNIX Operating System
The /etc/inittab file is referenced only for
determining the default run level of the system.
All other previous tasks are handled by the new
Upstart procedure.
id:3:initdefault
UNIX Operating System
UNIX-like runlevels
0 - halt (Do NOT set initdefault to this)
1 - Single user mode
2 - Multiuser, without NFS (The same as 3, if
you do not have networking)
3 - Full multiuser mode
4 - unused
5 - X11
6 - reboot (Do NOT set initdefault to this)
UNIX Operating System
UNIX-like performance tools
sar - command is performance monitoring
tool. It can find out what Linux is doing all
the time. It can generate report and email
them to sys admin.
vmstat - command that reports information
about processes, memory, paging, block IO,
traps, and cpu activity.
free command displays the total amount of
free and used physical and swap memory in
the system, as well as the buffers used by the
kernel.
UNIX Operating System
Linux performance tools
iostat - command is used for monitoring
system input/output device loading by
observing the time the devices are active
in relation to their average transfer rates
i.e. it is useful to monitor disk
throughput.
UNIX Operating System
UNIX-like shutdown command
The shutdown command is used to
shutdown the system in a safe way.
After bringing down the system,
shutdown command can halt or reboot
the system according to the options that
are specified.
Example: shutdown –h now
UNIX Operating System
/etc/rc.d
init.d rc0.d rc2.d rc4.d rc6.d
rc.sysinit
rc rc1.d rc3.d rc5.d rc.local
/etc
rc
rc4.d
init.d
rc0.d
rc5.d
rc.sysinit
rc1.d
rc6.d
rc2.d
rc.d
rc3.d
rc.local
UNIX Operating System
/etc/rc.d/rc0.d
Explain the k and s script prefixes
Explain the two digit numbering
Knoppix software directory names are
similar but slightly different.
UNIX Operating System
Roles of the kernel
1. Responsive - users
2. Autonomous - daemons
The kernel consists of a collection of low
level procedures. These procedures are called
system calls and they are the primary means
for a program to interact with other parts of the
system.
UNIX Operating System
The kernel supports the following file systems:
Demonstrate: /proc
cat filesystems
Demonstrate: pid_ppid.sh (use two putty
windows)
Demonstrate:
Execution of the newuid.pl and
process.sh scripts
UNIX Operating System
Points of interest
MBRs are not present on non-partitioned
media like floppies, super floppies or other
storage devices.
Moving Around in UNIX
uptime
w
who –r
who am i
Break-out problems
 What functionality does the mingetty or
getty perform?
 Define the kernel responsive and
autonomous functions?
 What system functionality does the
/etc/fstab file provide?
 What functionality does the
/etc/sysconfig directory provide?
 What functionality does the /etc/inittab
file provide?
Hands on information
Lab Assignment 8-1, Installation
Exercise due November 9, 2014
Lab Assignment 9-1,Startup
/Shutdown due November 16, 2014
Lab Assignment 10-1, 10-2
Account/LDAP/Process due
November 23, 2014
After class assistance
 Questions
 Comments
 Concerns
I
am available after this Franklin Live
session to discuss any problems and/or
concerns regarding the lab assignments
Lab Assistance available by phone
and/or email