Transcript Operating System [OS]

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System Administrator
Responsible for?
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Install OS
Network Configuration
Security Configuration
Patching
Backup
Performance Management
Storage Management
User Management
TroubleShooting & Maintainance
Vendor Management
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Who You Work with
Network
Team
Storage
Admin
Vendors
Facilities
Backup
Admin
Sys
Admin
Noc/Help
Desks
Database
Admin
Application
Team
Security
Team
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http://mazzakolinux.com Diff betwn Unix and Linux
Diff mac lin How many linux distro
Operating System [OS]
OS
Unix
AIX(IBM)
Windows
HPUX
Oracle
Solaris
Linux
Redhat
Suse
Debain
Most Popular Linux Popular linux by catogery
Ubuntu
Another link diff unix and linux
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Mint
http://spacebug.com/effective_development_environments/
Environment
Test Environment
•Development or
sandboxing
Development
Environment
•Integration, developer
testing and side effects
Staging Environment
•Performance testing,
quality Assurance,
•Check if there is any
negative impact on the
existing functionality
QA Environment
•Pre-production
environment
•Final testing prior to
deploying to production
•Serves endusers/clients
Production
Environment
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Link to severity Level
Red Hats version of severity Level
Severity Level
Severity 1 (urgent) :
Severity 2(High):
Severity 3(Medium):
Severity 4(Low):
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What is Operating System
• A software program designed to act as an
interface between a hardware and the user.
• It controls the hardware, manages system
resources and supervises interaction between
the system and its users.
User
Shell
OS
kernel
Hardware
Kernel
• Kernel : Core of the Unix OS. It interacts with
the hardware. It is loaded into memory when
the system is booted. Its functions are
- the kernel is responsible for memory
management, process and task management,
and disk management.
- The kernel connects the system hardware to
the application software
Shell
• Simply put, the shell is a program that takes your
commands from the keyboard and gives them to the
operating system to perform. In the old days, it was the
only user interface available on a Unix computer.
Nowadays, we have graphical user interfaces (GUIs) in
addition to command line interfaces (CLIs) such as the
shell.
• On most Linux systems a program called bash (which
stands for Bourne Again SHell, an enhanced version of
the original Bourne shell program, sh, written by Steve
Bourne) acts as the shell program. There are several
additional shell programs available on a typical Linux
system. These include: ksh, tcsh and zsh.
Kernel and Shell
What is the difference between a kernel and shell?
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What happens if we have ONLY the kernel BUT NO shell?
You then have a machine with the actual OS but there is NO way you can use it. There is no
"interface" for the human to interact with the OS and hence the machine. (Assuming GUIs don't
exist, for simplicity :)
What happens if we have ONLY the shell BUT NO kernel?
This is impossible. Shell is a program provided by the OS so that you can interact with it. Without
the kernel/OS nothing can execute (in a sense, not 100% true though, but you get the idea)
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A shell is just a program that offers some functionality that runs on the OS. The kernel is the
"essence/core" of the OS. The words can be confusing so here's the dictionary definition of kernel:
[code]Kernel: a softer, usually edible part of a nut, seed, or fruit stone contained within its hard
shell.[/code]
See how the words kernel/shell relate? That's the origin of it and its borrowed use in computing.
The kernel is the essence/core of the OS. You access the machine via the OS and the OS via a "shell"
that seems to "contain" the kernel.
Linux Operating System
Kernel
Shell
• Bourne Shell (sh) -- This shell does not have the interactive
facilities provided by modern shells such as the C shell and Korn
shell.
• C Shell (csh) -- It provides a C-like language with which to write
shell scripts - hence its name.
• Korn Shell (ksh) -- It provides all the features of the C and TC shells
together with a shell programming language similar to that of the
original Bourne shell.
• Bash Shell(bash) -- Bash provides all the interactive features of the
C shell (csh) and the Korn shell (ksh). Its programming language is
compatible with the Bourne shell (sh).
Absolute Path vs Relative Path
Good link for Paths
Video link for Paths
PATH
• Absolute Path:-> An absolute path is defined as the
specifying the location of a file or directory from the root
directory(/). In other words we can say absolute path is a
complete path from start of actual filesystem from /
directory. Eg: /var/ftp/pub
• Relative Path:-> Relative path is defined as path related to
the present working directory(pwd). Suppose I am located
in /var/log and I want to change directory to
/var/log/kernel. I can use relative path concept to change
directory to kernel .Eg: pwd
/var/log
cd kernel
UseFul commands
http://linuxcommand.org/lc3_learning_the_shell.php
http://www.linuxtraining.co.uk/download/new_linux_course_modules.pdf
https://portal.tacc.utexas.edu
FileSystem Layout
Directory Layout
Volume group (vgcreate)
Logical volume (lvcreate)
Logical Volume (pvcreate)
mount –t ext4 /dev/appvg/sharelv /share
mount –t ext4 /dev/appvg/datalv /data
Mount point
Logical Volume
Lvcreate –L 500 –n
mkfs.ext4
Mount point
/data
500MB
Logical Volume
datalv appvg
Lvcreate –L 1024 –n
mkfs.ext4
/dev/appvg/datalv
1GB
sharelv appvg
/dev/appvg/sharelv
/share
lvextend –L +500 /dev/appvg/datalv
free
18.5 GB
resize2fs /dev/appvg/datalv
vgcreate appvg /dev/sdb1 /dev/sdb2
/dev/appvg
Volume Group
Physical Partition pvcreate /dev/sdb1
Physical Partition
/dev/sdb1
/dev/sdb2
/dev/sdb
10 GB
Physical Hard Drive
20GB
pvcreate dev/sdb2
10GB
fdisk /dev/sdb
20 GB