Notes

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>


#define BUF_SIZE 8192

int main(int argc, char* argv[]) {



int fileInput; //to open the file
ssize_t ret_in, ret_out;
char data;
char line[50][100]; //store all the data in the file as
int n=0;
int i=0,j=0; //for using in a loop

printf("****** all lines of file nn");
fileInput= open (argv [1], O_RDONLY); //open the files
while((n=read(fileInput,&data,sizeof(char)))!= 0) //read the file until eof
{
if(data!='n') //this is true if it is not new line it reads character from one line
{
line[j][i]=data; //add data to a array
i++;
}
else
{
printf("%sn",line[j]); //this prints if argv[2] is in line
i=0; //put it zero
j++;
}

}
j=j-1;
printf("******* Lines required to print ***** n");
n=atoi(argv[2]); //get integer number
// printf("%d",n);
for(;n>=0;n--) //print from last
{
printf("%sn",line[j-n]);
}
}









#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include<string.h>

#define BUF_SIZE 1
int main(int argc, char* argv[])
{

int totallines =0;
char *buff;
char buffer[BUF_SIZE];
int selectedlines=atoi(argv[1]);
int input_fd;
char array[10];
input_fd = open (argv [2], O_RDONLY);
while((read (input_fd, &buffer, BUF_SIZE)) > 0){
if(buffer[0] =='n'){
totallines = totallines +1 ;

}

}
printf(" Total lines in a file : %dn",totallines);
//Points the pointer of read into place from where we want to learn
lseek(input_fd, 0, SEEK_SET);
int linestoskip = totallines-selectedlines;
int counter =0;
printf("Lines to skip in a file : %dn",linestoskip);
while((read(input_fd,&buffer,1))>0){

if((buffer[0]=='n')&&(counter<linestoskip)){
counter++;
}
else if(counter>=linestoskip)
{printf("%c",buffer[0]);
}}
close(input_fd);


return 0;
}