I was asked how to implement the unix tail command in perl
$ tail.pl t.txt 10 (display last 10 lines)
I kind of managed with the simple ARRAY and they playing around with the $#Array etc.
But they wanted without an array.
Any inputs ?

you can use the following shell command in your perl script .

 `cat filename|tail -10f ;`

This may not be accepted as well. But this can be done in numerous ways ! One way is here :

maintain a structure which stores the line number and the size of the file at that time.
eg 1 - 10bytes, 2 - 18 bytes ... you'll have to have a counter to increase the number of lines to find out the number of lines in the file. once you are through the file, you'll know the size of the file at any nth line. use sysseek to move the file pointer back to that position ( last 10 )and then start reading till the end.

Please try this capan module

  use File::Tail;
  $file=File::Tail->new("/some/log/file");
  while (defined($line=$file->read)) {
      print "$line";
  }

  use File::Tail;
  $file=File::Tail->new(name=>$name, maxinterval=>300, adjustafter=>7);
  while (defined($line=$file->read)) {
      print "$line";
  }

if we  will passed 2  argument , in that first is  filename  and  second  is no. of  last line then  u can use following  program :

#! /bin/perl

open(MYFILE,$ARGV[0]);

@array = ;
#print @array ;
$numline = @array;
$numprintline = $numline - $ARGV[1] ;
while($numprintline != $numline)
{
        print "$array[$numprintline]" ;
        $numprintline++;
}

#!/usr/bin/perl 
my $count = $ARGV[1];  ---> the number of lines to be printed
while(<>) { ----> reading file passed as arg
my $x = $.;  -----> assigning line number to $x
if ( $count >= $x )
{ print "line number $x: $_n"; }
else { exit; }
}

I think the point to not using arrays is the fact that loading large files in to an array is expensive.
$times = 10; # this is the number of lines

open(FILE, "$file") or die ("...");
seek(FILE, 0,2);
my $counter =0;
while ($counter < $times && seek(FILE, -2,1)) {
  read(FILE, $chr, 1);
  if ($chr eq "n") { $counter++ }
}

while () {
  print;
}

close(FILE);

How about opening the file twice and get two filehandles, and then navigate:
#!/usr/bin/env perl
# Usage: $0
use warnings;
use strict;

open(FILE1,"$ARGV[0]") or die $!;
open(FILE2,"$ARGV[0]") or die $!;

my $count = $ARGV[1];

while($count--) {
    ;
}

while() {
    ;
}

print ;

close(FILE1);
close(FILE2);

cat  | perl -e '$i = 0 ; map { print $_ if ($i++ < 10) } reverse (<>)'

Try this

#!/usr/bin/perl
use strict;
use warnings;

open(FH,"FILENAME") or die "$!";
while ()
{
chomp;
}
print "n$.";
my $x= $. - 10;

close (FH);

open(FH,"FILENAME") or die "$!";
while ()
{
chomp;
if ($.>=$x)
{
  print "$.->$_";
}

}
close (FH);

I think below answer is suitable.

Code
open FILE, "imp.txt" or die $!;
while ($line=<FILE>) {
 push @arr,$line;
}
print "
 
 
";
$m=$ARGV[0];
for(;$m > 0;$m--){
print @arr[-$m];}

Open file, read and print until number of required lines is reached. Memory is saved by not slurping the entire file into an array.

Code
$fileName = shift;
$lines = shift;
print "tailing file $fileName for $lines lines...
";
 
open FH, $fileName or die "Could not open $fileName";
 
    while ($l = <FH>) {
        print $l; --$lines;
        last if $lines == 0;
    }
close FH;

Code
#!/usr/bin/perl
 
$fileName = shift;
$lines = shift;
print "tailing file $fileName for $lines lines...
";
 
open FH, $fileName or die "Could not open $fileName";
 
    while ($l = <FH>) {
        push @ar, $l; --$lines;
        last if $lines == 0;
    }
 
    while ($l = <FH>) {
        push @ar, $l;
        shift @ar;
    }
 
close FH;
 
foreach (@ar) {
    print;
}
 

You can also try this : Create two pointers and make them $count apart. Move one of the pointer to EOF and keep simultaneously moving the other pointer so that it is $count before. Now use the second pointer to print the last $count lines.

Code
#!/usr/bin/env perl 
use warnings;
use strict;
 
open(FILE1,"$ARGV[0]") or die $!;
open(FILE2,"$ARGV[0]") or die $!;
 
my $count = $ARGV[1];
 
#After this loop FILE1 points to line after $count
while($count--) {
my $line = <FILE1>;
    ;
}
 
#After this loop FILE1 points to EOF and FILE2 points $count before EOF
while(<FILE1>) {
my $line = <FILE2>;
    ;
}
 
#Print the last $count lines before EOF
while(<FILE2>){
print ;
}
 
close(FILE1);
close(FILE2);

Just use .. opertor using array just check the length of the array minus with input give by the user take a difference and do it sample code is below.

Code
 
#! /usr/bin/perl
 
my @arry=qw(1 2 3 4 5 6 7 8 9);
 
my $len=$#arry;
 
print "Enter the number";
 
$l=<stdin>;
 
$result=$len-$l;
 
$res=@arry[$len] -@arry[$result];
 
 
foreach my $i (@arry[$result+1].. @arry[$len])
{
  print "
";
 print $i;
 
}