CENG 328 OPERATING SYSTEM

Quiz 1

1)      Create a directory named as your name under your home directory.

$ mkdir betul

 

2)      Create a file called “cars” in this directory in which  the cars mercedes,bmw,opel and audi are listed.

$ cat > cars

mercedes

bmw

opel

audi

^D

$

3)      Sort the car list in the file and store the sorted list to the file called “sorted”

$ sort  <  cars  > sorted

4)      Create a folder called “new” under the directory that you’ve previously created and copy the file “sorted” into this folder.

$ mkdir betul\ new

$ cp sorted betul/ new

5)      Rename the file “sorted” as “sorted_file”

$ mv sorted sorted_file

6)      Delete the file called “cars”

$ rm cars

7)      Write a command that displays the number of the lines which doesn’t have the word “bmw” in the file “sorted” and stores the result to the file result under your home directory

$ grep –vc bmw sorted > result

8)      Write a command that displays the number of the online users at the moment

$ who | wc -l

9)      Run a sleep process,send it to background and kill it.

 1.

$ sleep 100 &

[223] 770

$ ps

770 sleep 100

$ kill -9 770

2.

$ sleep 100

^Z

$ps

625 sleep

$ kill -9 625

10)  Give read and execute permissions to  the user and group and remove rest of the permissions for one of the files that you’ve created

- r – x  r – x - - -

   5         5      0

$ chmod 550 result





Lab3.  Shell Programming

 Shell programs are a file that holds the one or more unix or linux commands.

 

A .Input and Output

 

echo : this command is used for standard output

Use echo command to display text or value of variable.

echo [options] [string, variables...]
Displays text or variables value on screen.
Options
-n Do not output the trailing new line.
-e Enable interpretation of the following backslash escaped characters in the strings:
\a alert (bell)
\b backspace
\c suppress trailing new line
\n new line
\r carriage return
\t horizontal tab
\\ backslash

For e.g. $ echo -e "An apple a day keeps away \a\t\tdoctor\n"

 

Ex1.

clear
echo "Knowledge is Power"

 

ex2. Script to print user information who currently login , current date & time

clear
echo "Hello $USER"
echo –e "Today is \c ";date
echo –e "Number of user login : \c" ; who | wc -l
echo "Calendar"
cal

B. Variables:

 

In shell programming declaring a variable before using it is not necessary. The value of the variable can be seen using $ sign before its name:

$ cat > myprog

message=”Hello world”

echo $message

^D

$ ./myprog

Hello world

$

 

read : this command is used for standard input

 

$ cat > myprog

echo input number

read number

echo your number is: $number

^D

$ ./myprog

input number

5

your number is: 5

$

 

 

 

C. Arithmetic Operations

 

Operations: / ,- ,+ ,% ,* ,= ,>= ,<= ,< ,> ,& ,| ,( , ), a,o,!

 

expr op1 math-operator op2

 

Examples:
$ expr 1 + 3
$ expr 2 - 1
$ expr 10 / 2
$ expr 20 % 3
$ expr 10 \* 3
$ echo `expr 6 + 3`

 

x=`expr 3 \* 5`

echo $x

 

D. Testing

 

test : test command is used for testing operations. If test result is true, it returns true.

 

test –d  myfile : test the file called myfile whether it is a directory or not

test –f  myfile : test the file called myfile whether it is a file or not

test –r  myfile : test the file called my file whether it has  read permission or not

test –w  myfile : test the file called my file whether it has  write permission or not

test –x  myfile : test the file called my file whether it has execution permission or not

 

test str1=str2  : is str1 equal to str2

test str1!=str2 : is str1 not equal to str2

test n1 –eq n2 : is n1 equal to n2

test n1 –le n2  : is n1 less than or equal to n2

test n1 –ge n2 : is n1 greater than or equal to n2

test n1 –ne n2  : is n1 not equal n2

test n1 –lt  n2  : is n1 less than n2

 

E. If Statements

 

Syntax of the if statement:

 

if  condition

then

     command1

     command2

elif  

then

     command3

     command4

else

      command5

fi

 

example:

 

if test –r file1

then

     echo read permission

else

     echo no read permission

fi

 

 

 

 

 

 

 

F. Case Statement

 

Syntax of the case statement:

 

case variable-name in

option1 )

     command1

     command2

;;

option2 )

     command3

     command4

;;

*)

     command5

;;

esac

 

example:

read number

case $number in

1)

      clear

      ls;;

2)

     ls

     ;;

*)

     echo wrong ;;

esac

 

G. For statement

 

for  variable name  in  list

do

       execute one for each item in the list until the list is

       not finished (And repeat all statement between do and done)

done

 

for i in 1 2 3 4 5
do
echo "Welcome $i times"
done

 



Lists all words in the file called mylist

 

 
for i in `cat mylist` 

do

     echo $i

done    

 

 

for i in *           

do

 echo $i

done

 

 

H. While Statement

 

while [ condition ]
do
                 command1
                 command2
                 command3
                 ..
                 ....
done

 

i=1

while test $i –le 10

do

            echo “i= $i”

            i=`expr $i + 1`

done

 

I. Cut Statement

 

Usage: cut [OPTION]... [FILE]...
Print selected parts of lines from each FILE to standard output.
 -b, --bytes=LIST    output only these bytes
 -c, --characters=LIST  output only these characters
 -d, --delimiter=DELIM  use DELIM instead of TAB for field delimiter
 -f, --fields=LIST    output only these fields; also print any line
              that contains no delimiter character, unless
              the -s option is specified
 -n           with -b: don't split multibyte characters
 -s, --only-delimited  do not print lines not containing delimiters
   --output-delimiter=STRING use STRING as the output delimiter
              the default is to use the input delimiter
   --help   display this help and exit
   --version output version information and exit

With no FILE, or when FILE is -, read standard input.

 

cut –c 4-7 file2

$cat > deneme

deneme1;deneme2;deneme3;

deneme4;deneme5

^D

$cut –f2 –d ‘;’ deneme

deneme2

deneme5

$

 

Lab. Work 1

 

1. Write Script to find out biggest number from given three numbers. Numbers are supplies as command line argument. Print error if sufficient arguments are not supplied

 

 

2. Write script to print numbers as 5,4,3,2,1 using while loop

i=5

while test $i -ge 1

do

   echo -n " $i" 

   i=`expr $i - 1`

done

 

echo

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



if test $# -ne 3

then

   echo "ERROR..."

fi

 

case $2 in

"+" )

     out=`expr $1 + $3`

     echo "$1 + $3= $out "

     ;;

"-" )

    out=`expr $1 - $3`

    echo "$1 - $3= $out "

    ;;

"x" )

   out=`expr $1 \* $3`

   echo "$1 * $3= $out "

   ;;

"/" )

   out=`expr $1 / $3`

   echo "$1 / $3= $out "

   ;;

esac

 
3. Write Script, using case statement to perform basic math operation as +,-,*,/

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4. Write Script to see current date, time, username, and current directory

echo "Username = $USER"

echo -e "Date= \c";date

echo "Current working directory= `pwd`"

 

 

 

 

 

 

 

 



5. Write a shell script that writes “I love network Lectures” into a file then ask user, the word that will be changed and the new word that will be replaced with the old one.

 

 

 

6. Write script to determine whether given file exist or not, file name is supplied as command line argument, also check for sufficient number of command line argument