UNIX Programs

Q1. Write a shell script to generate a multiplication table.

echo Multiplication Table:
echo Which table do you want ? (Give Number):
read num
iter=1
while [ $num –le 5 ]
do
res=`expr $num \* $iter`
echo $num “*” $iter “=” $res
iter=`expr $iter + 1`
done


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Q2. Write a shell script that copies multiple files to a directory.

 iter=1
echo Enter new dir:
read nn
mkdir $nn
echo Enter number of files:
read na
while [  $iter –le $na ]
do
echo Enter file name:
read fn
cp $fn $nn
iter=`expr $iter + 1`
done

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Q3. Write a shell script which counts the number of lines and words present in a given file.

echo Enter a file name:
read fn
echo Number of Lines:
wc –l $fn
echo Number of Words:
wc –w $fn
echo Number of Characters:
wc –c $fn

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Q4. Write a shell script which displays the list of all files in the given directory.

echo Menu
echo 1.Short format display
echo 2.Long format display
echo 3.Hidden files to display
echo Enter ur choice:
read ch
case ch in
1)    ls $a;;
2)    ls –l $a;;
3)    ls –la $a;;
*)  echo Choice is not correct;;
esac

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Q5. Write a shell script(small calculator) that adds, subtracts, multiplies and divides the given two integers.

There are two division options: one returns the quotient and the other returns reminder. The script requires 3 arguments: The operation to be used and two integer numbers.
The options are add(-a), subtract(-s), multiply(-m), quotient(-c) and reminder(-r).

echo "Enter First Value "
read x
echo "Enter Second Value "
read y
while  [$q –ne 0 ]
do
echo “Enter –a for adding”
echo “Enter –s for subtraction”
echo “Enter –m for multiplication”
echo “Enter –c for Quotient”
echo “Enter –r for reminder”
read s
case $s in
-a)  p=`expr $x + $y`
     Echo "Sum = $p"
;;
-b)  p=`expr $x - $y`
     Echo "difference  = $p"
;;
-m)  p=`expr $x \* $y`
     Echo "Product = $p"
;;

-c)  p=`expr $x / $y`
     Echo "quotient = $p"

;;

-r)  p=`expr $x % $y`
     Echo “reminder = $p"
;;

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Q6. Write a shell script to reverse the rows and columns of a matrix.

Echo "Enter Number of rows"
read  r
Echo "Enter Number of columns"
read  c
i=0
echo "Enter elements"
until [ $i –eq `expr $r \* $c` ]
do
       read a[$i]
       i= `expr $i + 1`
done
i=0 ;  k=0
echo "Transpose of a Matrix"
until [ $i –eq $c ]
do
       j=0;
       until [ $j –eq $r ]
       do
              n= `expr $j \* $c`
              m= `expr $n + $i
              b[$k] = ${a[$m]}
              echo "${b[$k]} \t"
              k= `expr $k + 1`
              j= `expr $j + 1`
       done
       i = `expr $i + 1`
       echo "\n"
done

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Q7. Write a C program that counts the number of blanks in a text file using standard I/O.

#include <fcntl.h>
#include < sys/stat.h>
#include <stdio.h>
int main(int argc, char **argv)
{
   FILE *fd1;
   int n,count=0;
   char buf;
   fd1=fopen(argv[1],"r");
   while(!feof(fd1))
   {
   buf=fgetc(fd1);
     if(buf==' ')
         count=count+1;
   }
   printf("\n Total Blanks= %d",count);
return (0);
}

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Q8. Write a C program that counts the number of  blanks in a text file using system calls.

#include<fcntl.h>
#include<sys/stat.h>

int main(int argc, char **argv)
{
   int fd1;
   int n,count=0;
   char buf;
   fd1=open(argv[1],O_RDONLY);
   while((n=read(fd1,&buf,1))>0)
   {
     if(buf==' ')
         count=count+1;
   }
   printf("\n Total Blanks= %d",count);
return (0);
}
  
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Q9. Implement in C the cat Unix command using system calls.

#include<fcntl.h>
#include<sys/stat.h>
#define BUFSIZE 1
int main(int argc, char **argv)
{
   int fd1;
   int n;
   char buf;
   fd1=open(argv[1],O_RDONLY);
  printf("SuhritSolutions Printing Files\n");
   while((n=read(fd1,&buf,1))>0)
   {
    printf("%c",buf);
/*           or
     write(1,&buf,1);  */

   }
   return (0);
}
  

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Q10. Implement in C the following ls Unix command using system calls.

#include <sys/types.h>
#include <sys/dir.h>
#include <sys/param.h>
#include <stdio.h>

#define FALSE 0
#define TRUE 1

extern  int alphasort();

char pathname[MAXPATHLEN];

main()   {
int count,i;
struct dirent **files;
int file_select();

if (getwd(pathname) == NULL )
{ printf("Error getting pathn");
exit(0);
}
            printf("Current Working Directory = %sn",pathname);
        count = scandir(pathname, &files, file_select, alphasort);

                if (count <= 0)
        {         printf("No files in this directoryn");
                                exit(0);
                        }
                printf("Number of files = %dn",count);
            for (i=1;i<count+1;++i)
                 printf("%s  \n",files[i-1]->d_name);
               
        }


int file_select(struct direct   *entry)

{
if ((strcmp(entry->d_name, ".") == 0) ||(strcmp(entry->d_name, "..") == 0))
                         return (FALSE);
else
                return (TRUE);
        }

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Q11. Implement in C the Unix command mv using system calls.

#include<fcntl.h>
#include<stdio.h>
#include<unistd.h>
#include<sys/stat.h>
int main(int argc, char **argv)
{
   int fd1,fd2;
   int n,count=0;
   fd1=open(argv[1],O_RDONLY);
fd2=creat(argv[2],S_IWUSR);
rename(fd1,fd2);
unlink(argv[1]);
return (0);
}
     
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Q12. Write a c program for message passing using pipes.

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main()
{
int fd[2];
if(pipe(fd)<0)
exit(1);
if(fork())
{
close(fd[0]);
write(fd[1], “Message from Suhrit”12);
}
else
{
char buf[100];
close(fd[1]);
read(fd[0],buf,100);
printf(“Received by Students of SuhritSolutions:%s\n”,buf);
fflush(stdout);
}
exit(0);
}

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Q13. Write a C program that illustrates the creation of child process using fork system call. 

 One process finds sum of even series and other process finds sum of odd series.
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
int i,n,sum=0;
pid_t pid;
system(“clear”);
printf(“Enter n value:”);
scanf(“%d”,&n)
pid=fork();
if(pid==0)
{
printf(“From child process\n”);
for(i=1;i<n;i+=2)
{
printf(“%d\”,i);
sum+=i;
}
printf(“Odd sum:%d\n”,sum);
}
else
{
printf(“From process\n”);
for(i=0;i<n;i+=2)
{
printf(“%d\”,i);
sum+=i;
}
printf(“Even sum:%d\n”,sum);
}
}

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Q14. Write a C program that displays the real time of a day every 60 seconds.

     #include <stdio.h>
     #include <sys/time.h>     
     #include <sys/signal.h>

/* Declarations */
         void main();
     int times_up();

     void main()
     {

        for (; ;)
    {
      times_up(1);
     sleep(60);

    }                        
     }

 int times_up(sig)
     int sig;                            
     {
       long now;
       long  time(struct tms *ptr);
        char *ctime();

        time (&now);
        printf("It is now %s\n", ctime (&now));
return (sig);
     }

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Q15. Write a C program that illustrates file locking using semaphores.

#include <stdio.h>
 #include <sys/file.h>
 #include <error.h>
 #include <sys/sem.h>
 #define MAXBUF 100
 #define KEY 1216
 #define SEQFILE “suhritfile”
 int semid,fd;
 void my_lock(int);
 void my_unlock(int);
 union semnum
 {
      int val;
      struct semid_ds *buf;
      short *array;
 }arg;
 int main(])
 {
        int child, i,n, pid, seqno;
        char buff[MAXBUF+1];
        pid=getpid();
        if((semid=semget(KEY, 1, IPC_CREAT | 0666))= = -1)
        {
                 perror(“semget”);
                 exit(1);
        }
        arg.val=1;
        if(semctl(semid,0,SETVAL,arg)<0)
                 perror(“semctl”);
        if((fd=open(SEQFILE,2))<0)
        {
                 perror(“open”);
                 exit(1);
        }
        pid=getpid();
        for(i=0;i<2;i++)
        {
                 my_lock(fd);
                 lseek(fd,01,0);
                 if((n=read(fd,buff,MAXBUF))<0)
                 {
                        perror(“read”);
                        exit(1);
                 }
                 printf(“pid:%d, Seq no:%d\n”, pid, seqno);
                 seqno++;
                 sprintf(buff,”%d\n”, seqno);
                 n=strlen(buff);
                 lseek(fd,01,0);
                 if(write(fd,buff,n)!=n)
                 {
                        perror(“write”);
                        exit(1);
                 }
                 sleep(1);
                 my_unlock(fd);      
        }
 }
    void my_lock(int fd)
    {
              struct sembuff sbuf=(0, -1, 0);
              if(semop(semid, &sbuf, 1)= =0)
                   printf(“Locking: Resource…\n”);
              else
                   printf(“Error in Lock\n”);
    }
    void my_unlock(int fd)
    {
              struct sembuff sbuf=(0, 1, 0);
              if(semop(semid, &sbuf, 1)= =0)
                   printf(“UnLocking: Resource…\n”);
              else
                   printf(“Error in Unlock\n”);
    }

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Q16. Write a C program that implements a producer-consumer system with two processes.(using semaphores)

#include <stdio.h>   
#include <stdlib.h>     
#include <unistd.h>   
#include <time.h>   
#include <sys/types.h>  
#include <sys/ipc.h>    
#include <sys/sem.h>   

#define NUM_LOOPS    20   
int main(int argc, char* argv[])
{
    int sem_set_id;         
    union semun sem_val;     
    int child_pid;         
    int i;            
    struct sembuf sem_op;   
    int rc;             
    struct timespec delay;  

    sem_set_id = semget(IPC_PRIVATE, 1, 0600);
    if (sem_set_id == -1) {
    perror("main: semget");
    exit(1);
    }
    printf("semaphore set created,
 semaphore set id '%d'.\n", sem_set_id);

    sem_val.val = 0;
    rc = semctl(sem_set_id, 0, SETVAL, sem_val);
    child_pid = fork();
    switch (child_pid) {
    case -1:   
        perror("fork");
        exit(1);
    case 0:       
        for (i=0; i<NUM_LOOPS; i++) {
        sem_op.sem_num = 0;
        sem_op.sem_op = -1;
        sem_op.sem_flg = 0;
        semop(sem_set_id, &sem_op, 1);
        printf("consumer: '%d'\n", i);
        fflush(stdout);
                        sleep(3);
        }
        break;
    default:   
        for (i=0; i<NUM_LOOPS; i++)
            {
        printf("producer: '%d'\n", i);
        fflush(stdout);
        sem_op.sem_num = 0;
        sem_op.sem_op = 1;
        sem_op.sem_flg = 0;
        semop(sem_set_id, &sem_op, 1);
        sleep(2);
        if (rand() > 3*(RAND_MAX/4))
        {
                delay.tv_sec = 0;
                delay.tv_nsec = 10;
                nanosleep(&delay, NULL);
        }
        }
        break;
    }

    return 0;
}
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Q17. Write a C program that illustrates inter process communication using shared memory system calls.

 #include <stdio.h>
 #include<sys/ipc.h>
 #include<sys/shm.h>
 #include<sys/types.h>
 #define SEGSIZE 100
 int main(int argc, char *argv[ ])
 {
        int shmid,cntr;
        key_t key;
        char *segptr;
        char buff[ ]=”Hello world”;
        key=ftok(“.”,’s’);
        if((shmid=shmget(key, SEGSIZE, IPC_CREAT |
IPC_EXCL | 0666))= = -1)
        {
                if((shmid=shmget(key,SEGSIZE,0))= = -1)
                {
                      perror(“shmget”);
                      exit(1);
                }
        }
        else
        {
               printf(“Creating a new shared memory seg \n”);
               printf(“SHMID:%d”, shmid);
        }
        system(“ipcs –m”);
        if((segptr=shmat(shmid,0,0))= =(char*)-1)
       {
              perror(“shmat”);
              exit(1);
       }
       printf(“Writing data to shared memory…\n”);
       strcpy(segptr,buff);
       printf(“DONE\n”);
       printf(“Reading data from shared memory…\n”);
       printf(“DATA:-%s\n”segptr);
       printf(“DONE\n”);
       print(“Removing shared memory Segment…\n”);
       if(shmctl(shmid,IPC_RMID,0)= = -1)
             printf(“Can’t Remove Shared memory Segment…\n”);
      else
            printf(“Removed Successfully”);
 }

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Q18.Write a C program that illustrates the following.
a) Creating a message queue.
b) Writing to a message queue.
c) Reading from a message queue.

#include <stdio.h>
 #include <sys/ipc.h>
 #include <fcntl.h>
 #define MAX 255
        struct mesg
        {
              long type;
              char mtext[MAX];
        }  *mesg;
        char buff[MAX];
 main()
 {
        int mid,fd,n,count=0;;
        if((mid=msgget(1006,IPC_CREAT | 0666))<0)
        {
                printf(“\n Can’t create Message Q”);
                exit(1);
        }
        printf(“\n Queue id:%d”, mid);
        mesg=(struct mesg *)malloc(sizeof(struct mesg));
        mesg ->type=6;
        fd=open(“fact”,O_RDONLY);
        while(read(fd,buff,25)>0)
        {
                strcpy(mesg ->mtext,buff);
                if(msgsnd(mid,mesg,strlen(mesg ->mtext),0)== -1)
                     printf(“\n Message Write Error”);
        }

        if((mid=msgget(1006,0))<0)
        {
                printf(“\n Can’t create Message Q”);
                exit(1);
        }
        while((n=msgrcv(mid,&mesg,MAX,6,IPC_NOWAIT))>0)
                write(1,mesg.mtext,n);
                count++;
        if((n= = -1)&(count= =0))
                printf(“\n No Message Queue on Queue:%d”,mid);

 }