For Part 1 try the following snippet which calls the unix tail function: 
system("tail -10 inputFile.txt >> outputFile.txt");

open <FILE, "</path/to/outputFile.txt"> or die "can't open file: $!\n"
+;
   #do whatever here
close FILE or die "can't close file $!\n";

[download]

In general, I do rely on calling Unix command line utilities for tools that I don't want to reinvent. I don't work on PC so much, so I'm not familiar with the situation there.

A 'pure' Perl implementation might involve counting all the lines in a file and then using the count to generate a new file which you would then process. This is more a Part 2ish approach. So for Part 2, try something like the following: 

@input = <FILE>;
$i = 0;
foreach ($line (@input)) {
   $i++;
   if ($i >= 1034 || $i <= 1047) {
   #process here
   } 
}
close FILE or die "can't close file: $!\n";

[download]

To count all the lines, just count your way through the foreach loop and use the final $i value as the number of lines in your file. This should help, I hope.

Have a look at chapters 8 and 9 of the Perl Cookbook - I just noticed a simple and elegant way of doing the line counting there. You might also try working with this PerlMonks node: Parsing a file one line at a time. I found this one to be quite helpful for this type of problem in general.

Good luck!

MadraghRua
yet another biologist hacking perl....

In reply to Re: Simulating UNIX's "tail" in core Perl by MadraghRua
in thread Simulating UNIX's "tail" in core Perl by gryphon

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