Dead lock:

Dead lock can be defined formally as follow ...

A set of process is dead lock.If each process in the set is waiting for an event that only another process in the set can calls.

Condition for dead lock:

Commander all showed that condition must showed there should be the dead lock.

Mutual-exclusion condition:

Each-resource is either currently assigned to exactly one process (or) is available.

Hold and wait:

Process currently holding resources granted earlier can request new resources.

Non preemptive condition:

Resource previously granted can not be forcefully taken away from the process.They must be explicitly released by the process holding them.

Circular wait:

They must be a circular chain of two (or) more process each of which is waiting for a resource held by the next number of the chain.

All four of then condition must be present dead lock to occur.It one of them is absent no dead lock is possible.

Dead lock modeling:

Resource node represent with square process node represent with circle.

p0      p1

|         |

r0      r1

A request     R                                         

B  request    S                          

C   request    T                                           A->B->C->A

A   request    R

B  request     S 

C    request  T

Arithmetic shell script:

To carry out arithmetic operation on variable have to use the command expression catch is able to carry arithmetic operation.

Ex: 

a=10 

b=5

echo  expression $ a+$b

echo expression $ a/*$b

  while evaluating an expression expression perform various arithmetic according to the following priorities.

Four decision making 

a) if -then-fi

b)if-then-fi

c)if-max-if-else-fi

d)case-asac

if-then-else if statement 

if(control command)

then statement

else statement

if 

read number

if($number - &to)

then 

echo regestive integer

else

echo positive number

is

pipe

pipe are used for inter process communication between two related process normal a pump is create by a process that process calls fork().

The pipe is used between parent and child. 

syntax:

pipe create calling function pipe int pipe(int Fields [2]);

Two file description are returned 2 fields arguments.

 SHELL PROGRAMING

Chemicals in shampoos linked to birth defects

The parent's exposure to chemicals often used as personal product such as detergents,shampoos,and conditioners may be associated with birth defects in children.The study conducted by Edward medicine college in the US showed that the chemical known as quaternary ammonium compounds or 'squats' can lead to birth defects of the brain,spine or spinal cord in children.

Place to tour as per as your zodiac sign in 2018

At the beginning of new year ,people mostly come up with new resolutions. Now,here are some places you can travel to based on your Zodiac sign >Aries:Andaman & Nicobar islands

>Taurus:Dubai >Gemini:Thailand>Cancer:Kerala >Leo:Singapore > Virgo:Jaisalmer >Libra:paris>Scorpio:Bali Sagittarius:Bhutan> Capricorn:Sri Lanka> Pisces:Maldives.

 GOVT SCHOOL CCTV's IN EVERY CLASS

IN a bid to ensure safety & security of students.In many school and college key cctv's from security of students and teachers.But INDIA less number of school and college are there in cctv's .Because INDIA only developing country .Not a developed country , But in 2018 INDIA was implementing cctv's at school and collages.

Delhi govt school to get CCTV's in every class 

In a bid to ensure safety & security of students.

Delhi CM Arvind kejriwal has annound the installation of CCTV's cameras in every class of govt-run schools. He added that parents can easily monitor their children in the classroom in real time basis on phone itself which make the plan transport & accountable .He also directed the officials to complete CCTV's installation in 3 months.