#! perl -slw
use strict;

sub compactPath {
    my( $p, $n ) = @_;
    my $discard = length( $p ) - $n + 3;
    my $min = $p =~ m[\\[^\\]+$];
    $p =~ s[.{$min,$discard}(?=\\[^\\]+$)][...];
    return $p;
}

my $path = "C:\\path1\\path2\\sample.txt";;
print $path;
print compactPath( $path, $_ ) for reverse 0 .. length $path;

__END__
C:\test>junk47
C:\path1\path2\sample.txt
C:\path1\pa...\sample.txt
C:\path1\p...\sample.txt
C:\path1\...\sample.txt
C:\path1...\sample.txt
C:\path...\sample.txt
C:\pat...\sample.txt
C:\pa...\sample.txt
C:\p...\sample.txt
C:\...\sample.txt
C:...\sample.txt
C...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt
...\sample.txt