A BAD news to all...

Our Head Of the Department(Information Technology), Prof.P.Duraiswamy was expired today(5-12-11) noon.....

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"Our hearts are saddened by your loss and our thoughts and prayers are with you"

"Lets Pray for him at this time of sorrow"......

check it out...

O.S->WAIT SYSTEM CALL

WAIT  SYSTEM  CALL

 AIM:

            To write a c program to implement wait system calls.

 ALGORITHM:

     STEP 1:  Start the program.

     STEP 2:  Include the header files.

     STEP 3:  Declare the variable pid and assign i=0,pid=fork( ).

     STEP 4:  If pid=0 then child starts.

     STEP 5:  For i=0,i less than 10 print the value of i.

     STEP 6:  Child process ends.

     STEP 7:  Else child ends now in parent process.

     STEP 8:  Stop the program.

PROGRAM:

  #include<stdio.h>

  #include<sys/wait.h>

  int main()

  {

    int pid,i=0;

    printf("\n ready to fork");

    pid=fork();

    if(pid==0)

     {

       printf("\n child starts\n");

       for(i=0;i<10;i++)

       printf("\n%d\n",i);

       printf("child ends\n");

       exit(0);

     }

    else

     {

       wait(0);

       printf("child ends now in parent process");

       printf("exist status");

     }

  }

OUTPUT:

$./a.out

 Ready to fork

 Child starts

 0

 1

 2

 3

 4

 5

 6

 7

 8

 9

 Child ends

 Ready to fork child ends now in parent process

 exit status

OS-> STAT SYSTEM CALL

STAT SYSTEM CALL

 AIM:

           To write a c-program to implement stat system call.

 ALGORITHM:

    STEP 1:  Start the program.

    STEP 2:  Include the header file as <sys/stat.h>

    STEP 3:  In main have three arguments such as i,avge,argv.

    STEP 4:  Declare sbuffs as structure variable that structure have stat.

    STEP 5:  To display the filename,node1,user id,group id,mode of the

                    corresponding system.

    STEP 6:  Stop the program.

PROGRAM:

 #include<stdio.h>

 #include<sys/stat.h>

 main(int i,int avge,char**argv)

  {

    struct stat sbuff;

    if(!stat(argv[i],&sbuff)==-1)

    printf("could not stat file",1);

    printf("\n file name:%s",argv[i]);

    printf("\n inode no:%i",sbuff.st_ino);

    printf("\n user id:%u",sbuff.st_uid);

    printf("\n groupid:%g",sbuff.st_gid);

    printf("\n mode:%f",sbuff.st_mode):

    printf("\n size of flie:%d",sbuff.st_size);

    exit(0);

  }

OUTPUT:

 $ cc stat.c

 $./a.out

 File name: HOSTNAME=net64

 inode no: 0

 User id: 24641422

 Groupid:-1.79259

 Mode:-1.792591

 Size of the file:0

OS-> I/O SYSTEM CALL

I/O SYSTEM CALL

AIM:

          To write a c program using i/o system call to open, read and write a file.

ALGORITHM:

        STEP 1: start the program.

        STEP 2: include the header file as<fcntl.h> and <sys/stat.h>

        STEP 3: create the buffer variable with size of 50.

        STEP 4: create a new file using cat and write the data into the file.

        STEP 5: open a file in read only mode and read the content of file and place                                                                                                                 

                       it in buffer.    

        STEP 6: write the buffer content to a file which is opened in write

                       only mode.

        STEP 7: close the files.

        STEP 8: stop the program.

PROGRAM:

 #include<stdio.h>

 #include<fcntl.h>

 #include<sys/stat.h>

 #include<sys/type.h>

 int main()

  {

   int fp1,fp2,n;

   char buff[50];

   fp1=open("a.txt",O_RDONLY);

   fp2=open(“b.txt”,O_CREAT|O_WRONLY|O_TRUNC,S_IRUSR|S_IWUSR);  

   while(n=read(fp1,buff,50)>0)

   write(fp2,&buff,50);

   close(fp1);

   close(fp2);

   exit(0);

  }

OUTPUT:

  $ cc ios.c

  $./a.out

  $ cat b.txt

  hai

  hello

OS-> LISTING OF FILES USING UNIX COMMAND

LISTING OF FILES USING UNIX COMMAND

AIM:

      

        To write a c program to list the files using UNIX commands.

ALGORITHM:

      

        STEP 1: Start the program

        STEP 2: Create the new child process using the fork ( ) in UNIX

        STEP 3: List the files available in specified directory using execl function.

        STEP 4: The list of available files are displayed in the terminal.

        STEP 5: Stop the program.

PROGRAM:

 #include<stdio.h>

 #include<unistd.h>

 main()

  {

    int pid;

    pid=fork();

    if(pid==0)

    {

      printf("execution starts\n");

      execl("/bin/ls","ls","-1",(char*)0);

      printf("execution did not work\n");

    }

    else

    {

      wait(0);

      printf("parent:is completed in child");

    }

  }

OUTPUT:

$cc list.c

$./a.out

Execution starts

a.c

child.c

tharu.sh

sam.sh

y.tab.h

parent is completed in child

OS-> GETPID SYSTEM CALL

GETPID SYSTEM CALL

AIM:

   

            To write a c program to implement getpid system call.

ALGORITHM:

    STEP 1:  Start the program.

    STEP 2:  Include the header file.

    STEP 3:  Declare the variable pid.

    STEP 4:  Assign pid=fork().

    STEP 5:  If pid is greater than zero display the parent and child before

                    fork.

    STEP 6:  Else if pid==0 display parent and child on executing

    STEP 7:  Else display fork error.

    STEP 8:  Stop the program.

PROGRAM:

#include<stdio.h>

int main()

 {

   int pid;

   printf("before fork\n");

   pid=fork();

   if(pid>0)

    {

      sleep(1);

      printf("parent%d,\nchild%d",getpid(),pid);

    }

   elseif(pid==0)

    {

      printf("parent%d,\nchild%d",getppid(),getpid());

    }

   else

    {

      printf("\nfork error");

      exit(1);

    }

   printf("both executing\n");

   exit(0);

 }

OUTPUT:

 $ cc getpid.c

 $./a.out

 Before fork

 Parent 3406

 Child 3407 both executing

 Parent 3406

 Child 3407 both executing

OS->FORK SYSTEM CALL

FORK SYSTEM CALL

 AIM:

                To write a c-program to implement fork system call.

 ALGORITHM:

      STEP 1:  Start the program

    STEP 2:  Include the header file.

    STEP 3:  Declare the variable pid.

    STEP 4:  If pid=fork() is less than zero print "fork error".

    STEP 5:  Else if pid=0 print "child process" otherwise print "parent  

                   Process.                    

    STEP 6:  Display the output.

    STEP 7:  Stop the program.

PROGRAM:

   

     #include<stdio.h>

     main()

     {

       int pid;

       if((pid=fork())<0)

         {

           printf("fork error\n");

           exit(1);

         }

       else if(pid==0)

         {

           printf("child process\n");

         }

       else

         {

            printf("parent process\n");

            wait(0);

         }

     }

    OUTPUT:

    $ cc fork.c

    $./a.out

    Child process

    Parent process