May 2019
M T W T F S S
« Apr    
 12345
6789101112
13141516171819
20212223242526
2728293031  

Categories

WordPress Quotes

Old friends pass away, new friends appear. It is just like the days. An old day passes, a new day arrives. The important thing is to make it meaningful: a meaningful friend - or a meaningful day.
Dalai Lama
May 2019
M T W T F S S
« Apr    
 12345
6789101112
13141516171819
20212223242526
2728293031  

Short Cuts

2012 SERVER (64)
2016 windows (9)
AIX (13)
Amazon (34)
Ansibile (19)
Apache (133)
Asterisk (2)
cassandra (2)
Centos (209)
Centos RHEL 7 (264)
chef (3)
cloud (2)
cluster (3)
Coherence (1)
DB2 (5)
DISK (25)
DNS (9)
Docker (30)
Eassy (11)
ELKS (1)
EXCHANGE (3)
Fedora (6)
ftp (5)
GIT (3)
GOD (2)
Grub (1)
Hacking (10)
Hadoop (6)
horoscope (23)
Hyper-V (10)
IIS (15)
IPTABLES (15)
JAVA (7)
JBOSS (32)
jenkins (1)
Kubernetes (3)
Ldap (5)
Linux (188)
Linux Commands (166)
Load balancer (5)
mariadb (14)
Mongodb (4)
MQ Server (24)
MYSQL (84)
Nagios (5)
NaturalOil (13)
Nginx (32)
Ngix (1)
openldap (1)
Openstack (6)
Oracle (34)
Perl (3)
Postfix (19)
Postgresql (1)
PowerShell (2)
Python (3)
qmail (36)
Redis (12)
RHCE (28)
SCALEIO (1)
Security on Centos (29)
SFTP (1)
Shell (64)
Solaris (58)
Sql Server 2012 (4)
squid (3)
SSH (10)
SSL (14)
Storage (1)
swap (3)
TIPS on Linux (28)
tomcat (61)
Uncategorized (29)
Veritas (2)
vfabric (1)
VMware (28)
Weblogic (38)
Websphere (71)
Windows (19)
Windows Software (2)
wordpress (1)
ZIMBRA (17)

WP Cumulus Flash tag cloud by Roy Tanck requires Flash Player 9 or better.

Who's Online

27 visitors online now
3 guests, 24 bots, 0 members

Hit Counter provided by dental implants orange county

SHELL SCRIPTING Reference

SHELL SCRIPTING:

-shell is a command line interpreter

-it is interface b/w user & kernel

– it takes commands form the user and excute them

Shell  are different types:

Shell           developed   shellprompt                   executetioncommand

Bourne        SteveBorn   $                           sh

Corn           devidCorn   $                           ksh

Cshell                   billjoy                   %                          csh

Bash           born            $                           sh(or)bsh

Zsh             panel           $                           zsh

Shell variables:

There are two types of shell variables.

Unix Defined or system defined

User Defined

Unix Defined:-these are standed variable which are always accessable.the shell provide the values for these variables. These variables are usually used by the system we can change the variables as per over preference an custamize the system environment.

$ set

HOME=/user/pavan

HZ=100

IFS=space or tab or new line

LOGNAME=pavan

MAIL=usr/sped/mail/pavan

MAILCHEECK=600sec

OPTEND=1

PATH=/bin:/usr/bin:/usr/pavan:/bin:.

PS1=$primary shell prompt

Ps2= > -system prompt(default values)

SHELL=/bin/sh

TERM=vt100

TZ=ist-5:30

PATH:- Define the which shell  must search in order to command .

HOME:-store default working directory of the user.

LOGNAME:-store the log name of the user.

MAIL:-Define the file where the mail of user stored.

MAILCHECK:-define the duration after which shell checks whether the user received mail by default the values 600 sec

IFS:-define the internal felids separator which is space or tab or newline

SHELL:-define the name of you are working shell.

TERM:-define the name of the term and which you r working.

TZ:-define the name of the time zone in which you are working

User defined variable:-

These are defined by the user and used most exclusively  in shell programming

Rules for creating user shell variables

The first character should be alphabet or –

Eg:- -a= ,a=,b=,c=,d=

-no commas or blanks are allowed

Eg:-a,b=10 is worng

Variable names should be casesensitive

Eg:-name=,Name=,nAme=

Variable names should be a shell keywords.

SHELL keywords:

Key words are words which meaning as already been explained to the shell.

Keywords are also called as reverse words

The list of key words are in bourn shell

Echo  for     if       untill read   else    case   set     wait   fi       esas   uset   eval   while readonly          break do      shift   exec   continue      done  ulimit export         exit    umask                   return          frap

Echo statements: Echo command is used to display the message on the screen and it is used to display the values stored in a shell variable.

$echo “welcome”

Display output to the screen.

Double cotes are optional.

UNIX command should be in back cotes (`) in echo statement, otherwise it treats as a text.

$echo “todays date is : date”

O/p – todays date is: date

$echo “todays date is :`date`“

o/p-todays date is : fri apr 5 9:15 Gt 2013

$echo “no of files `wc –l file1` ”

o/p – no of files  10

$echo “my log in name`logname`

o/p – my login name is shahid

$echo “my present working directory is :`pwd`”

o/p – my present working directory is :/home/shahid

Shell variables:

$a = 10

$b = 20

$name = “shahid”

$echo $a – 10

$echo $b – 20

$echo $name – shahid

$mypath=/home/shahid/dir1

$cd $mypath

$pwd

/home/shahid/dir1

Null variables:

A variable which has defined but has not been given any value is known as a null variable.

$n=” “

$n=’ ‘

Constant: It is a fixed value it doesn’t change during execution of the program.

$readonly a

When the variable is made readonly the shell doesn’t allow you to change their values.

$unset a  -> the variable a and its value assigned to it are erased from shell memory.

Escape sequences:

echo “shahid\n”

echo “pavan”

\n – displays in new line

\n                newline                 $echo”shahid\nshaik”

\t                 tab                        $echo”shahid\tshaik”—-shahid         shaik

\b                backspace             $echo”pavan\bkumar”—-pavakumar

\”                 double quote                  $echo”\”pavankumar\””

\’                 single quote

\\                 backslash

Sample program:

Write a program to display list of files and directories and present working directories and no of users logged into the system.

Vi sample.sh

#! /bin/bsh

ls –l

pwd

who

:wq

How to execute shell script?

$sh sample.sh

$./sample.sh

We have to check the permissions and then we have to execute.

Chmod 775 sample.sh

Write a program to display the address?

#!/bin/sh

echo “100/14,20 th main\n”

echo “9th cross maruthi nagar\n”

echo”Bangalore\n”

:wq

$./address.sh

Write a program to count no of users are currently logged into the system?

Echo “ The no of users :`who|wc –l`”

:wq users.sh

./users.sh

Read input from program?

Echo “enter your name:”

Read name

Echo “hello $name how are you”

Execution:

Enter your name: shahid

Hello shahid how are you

Read is a command to read variable value from the input user or keyboard.

Read command reads value from the keyboard up to space or enter key.

echo “enter a, b, c values”

read a b c

echo $a,$b,$c

enter a b c values :3  4 5

3,4,5

write a program to read two numbers and display?

Echo”enter a ,b values”

Read a b

Echo $a  $b

Operators:

  1. Arthematic operators
  2. Relational operators

Numeric comparison

String comparison

  1. Logical operators

1.Arthematic operators : Addition(+) ,subtraction(-) multiplication(*),division(/),modulus division(%)

  1. Relational operators: -gt (>),- lt(<) ,- ge (>=),-le (<=),-eq(=),-ne(!=)
  2. Logical operators:

-And  -a

-Or    -o

-Nor   -!

Write a program to read two numbers and display sum diff pro and div?

Echo “enter 2 numbers”

Read a b

C = `expr $a + $b`

Echo  “ addition is $c”

D = `expr $a – $b`

Echo “subtraction is $D”

E = `expr $a \ * $b`

Echo “product is $E”

F = `expr $a / $b `

Echo “division is $F”

*_ ? [] —wild chard characters we will use “\”

Expr is a command to evaluating arthematic expressions.

But expr is capable of carrying out only integer arthematic.

Write a program to read 2 float numbers and display sum diff prod and divi?

Echo “enter 2 numbers”

Read a b

C = `echo $a + $b\bc`

Echo  “ addition is $c”

D = `echo $a – $b\bc`

Echo “subtraction is $D”

E = `echo $a \ * $b\bc`

Echo “product is $E”

F = `echo $a / $b\bc `

Echo “division is $F”àbc – basic calculator

IF statements:

If condition

then

————

————-

————-

Fi

  1. if condition

Then

————-

———–

Else

Fi

3.ifcondition

Then

—-

Elif condition

—-

Elif condition

—-

Fi

If 0-true

If 1-false

Cd $path

0-success

1-failure

Write a program to change directory?

Echo ”enter directory name”

Read dir

If [cd  $dir]

Then

Echo “changed to $dir”

Pwd

Fi

Write a program to copy a file?

Echo “enter source and target file names”

Read source target

If cp $source $target

Then

Echo “files have been copied successfully”

Else

Echo “failed to copy the file”

Fi

Write a program to search a string in a file?

Write a program to find greatest number of two numbers?

Echo “ enter two numbers”

Read a b

If [$a –gt $b]

Then

Echo “ $a is greatest number”

Else

Echo “$b is greatest number”

fi

write a program to check given number is even or odd?

Echo “ enter a number”

Read a

If [`expr $a%2` -eq 0]

Then

Echo “ even number”

Else

Echo “ odd number”

Fi

Text:-(we use conjection if)

If constantsthe  are generally  used in conjection text command.

Eg:-if text [condi]

If condi

If[condi]

The text command help us to find the contents of  a variable the no of variables and the type of file or kind of file permission.

The text command returns an exist status after evaluating the condition

Sy:-if text condition

Then

Commands

Else

Commands

Fi

Write a program to check how many users or working on the system

#!/usr/bin/bsh

Total=’ who|wc –l ‘

If text $total –eq 1

Then

Echo” u r only the user logged in “

Else

Echo “total no of users:$total”

Fi

Write a program to check the given number is +ve or –ve?

#!/usr/bin/bsh

Echo “enter a number in”

Read a

If text $a –gt 0

Then

Echo “ the entered no is +ve”

elseIf text $a –eq 0

echo “the entered no is 0”

elseif text $a –lt 0

echo “the entered no is –ve”

fi

write a program to find out student results

#!/usr/bin/bsh

Echo “enter subject marks”

Read m1 m2 m3

If text $m1 –ge 35

Then

If text $m2 –ge 35

then

If text $m1 –ge 35

Echo “pass”

Else

Echo “fail”

Elseif

Echo “fail”

Elseif

Echo “fail”

Fi

Write a program to print greatings.

Hour=’date | cut –c 12, 13’

If[hour –ge 0 –a $hour –lt 12]

Then

Echo “Good moring”

Elseif[$hour –gt 12 –a $hour –lt 17)

Echo “good afternoon”

Else

Echo “good evening”

Fi

Fi

File text command:

-s –true if the file exist and has a size>0

-f-true if the file exists and is not a directory.

-d-true if the exists is in directory

-c- true if the file exist

-r-true if the file exist it have read permission

-w-true if the file write permission

-x-true if the file execute permission

Write a program to check for ordinary file and display it contents

Echo “enter a file name to be opened”

Read filename

If text –f $filename

Then

Cat<$fname

Else

Echo “ file is not present “

Fi

Write a program to check given file an ordinary file or directory

Echo “enter a filename”

Read fname

If[-f $fname]

Then

Echo”it is an ordinary file”

Elseif[-d $fname]

Echo “it is a directory file”

Else

Echo “it is not an ordinary file”

Fi

Write a program to open a file if the doesn’t have read permission then assign the permission & open a file .

Echo “enter a file”

Read filename

If [-r $ fname]

Then

Cat <$fname

Else

Chmod u+r $fname

Cat<$fname

Fi

Write a program to append data to the file

Echo “enter a file”

Read fname

If[-f $fname]

Then

If[-w$fname]

Then

Echo “enter the content & press ctr+d at the end”

Cat>>fname

Else

Chmod u+w $fname

Cat>>fname

Fi

Else

Echo “enter the data press ctr+d”

Cat>fname

Fi

String text command:

Str1=str2-true if the strings are equal

Str!=str2-true if the strings not equal

-n str-true if the length of string is >0

-z str-true if the length of equal zero(=0)

Write a program to compare two strings

Echo”enter str1”

Read str1

Echo “enter str2”

Read str2

If text $str1=$str2

Then

Echo “both are equal”

Else

Echo “both are not equal”

Fi

Write a program to check given string is empty or not

Echo “enter a string “

Read string

If text –z $string

Then

Echo “string is empty”

Else

Echo “string is not empty”

Fi

CASE CONTROL STATEMENTS

Case value in

Choice 1)

___________

___________

;;

Choice 2)

—————-

—————-

—————-

;;

Choice *

———————–

——————–

;;

esac

The expression the following the case keyword is evaluate first the value that it yields is then mathch one by one against potential choices like choice 1 choice 2 ……………. choice n.when match is found then shell will execute all commands in that case upto ;; .this pair of semicolons placed at the end of each choice.

Eg:-

Echo “enter a number b/w 1 to 4”

Read num

Case $num in

Echo “ u entered one”

;;

Echo “u entered two”

;;

Echo “u entered three”

;;

Echo “u entered four”

;;

Esac

Write a program to check given character is uppercase alphabet or lower case alphabet or digit or special character.

Echo “enter a character”

Read ch

Case $ ch in

[a-z] echo “u entered lowercase charecters”

;;

[A-Z] echo “ u entere lower case charecters”

;;

[0-9] echo “u entered digits”

;;

?) echo “u entered special character”

;;

Esac

Write a program to display file contents or write on to the file or execute based on user choice

Echo “enter a filename”

Read fname

Echo “main menu”

Echo “***********”

Echo”r-readmode”

Echo “w-writemode”

Echo “x-excute mode”

Echo “enter mode”

Read mode

Case $ mode in

Choice r) If[-f $fname –a –r $fname]

Then

Cat<$fname

Fi

;;

Choice w) if[-f $fname –a –w$fname]

Then

Echo “enter data & press ctr+d”

Cat>>$fname

Fi

;;

Choice x) if[-f $fname –a –x $fname]

Then

$fname

Fi

;;

Choice *) echo “u r execute invalid input”

Esac

Exit statement:

It is used to terminate execution of shell programming

Eg:-$exit

Looping control statements:

While

Until

forloop

while:-

while condition

do

———–

————–

Done

Until:

Until condition

Do

——————

—————–

Done

Forloop:

For varable in value1,value2……………….valuen

Do

——————-

———————

Done

Write a program to display number from 1 to 10

Echo “enter no from 1 to 10”

I=1

While [$i –gt 10]

Do

Echo “$i”

I=”expr $i+1”

Done

Break Or continue statements:

Break:

When the keyword break is encounted inside any loop etc automatically passes to the first statement after the loop

While condition

Do

————–

————–

Break

——————-

————-

Done

Continue:

When the keyword continue is encounted inside loop control automatically passes to the beginning of the loop & continue from beginning of the loop .

Write a program to display file contents of the file existing

X=0

While test $x=0

Do

Echo “enter a filename”

Read fname

If text ! –f $name

Then

Echo “$fname is not found enter current file “

Continue

Else

Break

Fi

Done

Cat $ fname | more

Until: execute from false.then true it will not execute

Write a program to print no 1 to 10?

I=1

Untile [$i –gt 10]

Do

Echo $i

I=”expr $i+1”

Done

Sleep:

Sleep commmad stop the execution of the program that specified no of seconds.

Write a program to print no  from 1 to 10.

For i in 1 2 3 4 5 6 7 8 9 10

Do

Echo $i

Done

Command line arguments:
$0-first argument

$1-second argument

$./script.sh arg1 arg2…………………argn

$*-contains active string of an arguments

$#-contains no of arguments specified in the command

$?-it will store the last execution commands states.

 

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

  

  

  

Blue Captcha Image
Refresh

*

Protected by WP Anti Spam