My sincerest apologies for the amateurish code you're about to see... 
#!/usr/bin/perl 
use strict;
use warnings;

print "The lower the score the more stable the structure.", "\n",
      "Please set a limiting value e.g. -3: ", "\n";
my $value = <STDIN>;


open IN, "file.hairpin", or die $!;

my @trash;
my @treasure;

while (<IN>){
    if ($_ =~ /^>+/){
    push @treasure, $_;

    }elsif($_ =~ /^None+/){
    push @trash, $_;

    }elsif($_ =~ /(^d+)/){

## Here    I don't know how to incorporate the value I get from the us
+er with the value
## in the file
        
    }else{
    push @treasure, $_;
    }
}

close IN;

foreach my $stuff (@treasure){
    open SIFTED, '>>', "new_file.hairpin", or die $!;
    print SIFTED, $stuff."\n";
    close SIFTED;
}

[download]

In reply to Re^2: Easiest way to filter a file based on user input by Peter Keystrokes
in thread Easiest way to filter a file based on user input by Peter Keystrokes

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.