i dont know what you are trying to achieve, but even i had the same requirement for a XML file to calculate checksum after stripping all XML tags and bringing data into one line and calculating checksum crc32 on it , this was a requirement from one of our client

Why dont you try the below?

# call as: ConvertFindLaw.pl PilotLifeFindLaw.htm  
use 5.010;
use Switch;
use strict;
my $wholeFile;
my $INPUT_FILE = shift; 
my $FH; 
open(FH, $INPUT_FILE) or die "Bad $INPUT_FILE: $!"; ;
while (<FH>) { # print $line; # All lines printed
chomp $_; # This makes difference , if want it in one line
$wholeFile .= qq~$_~; # Just use quoted qq 
}  # Build a long string
$wholeFile .= qq~\n~; # This is needed, when you say u want it in one 
+line, there should one new line character after doing appending in wh
+ile loop, now when you do wc -l on this one, it will show one line
close(FH);
print $wholeFile; # front truncated here
[download]

* You should remember , if you are putting the resultant string in file and want to open it and see, i guess some editors have limitation in terms of number charcaters it can display in a single line, for ex: AIX5 , my vi editor cannot display more than 2048 characters in a single line.

As said by some of the monks , unless you specify what you are going to achieve, its difficult to suggest the solution.