Re^3: search and print in perl

[citromatik]

it goes on like this, Random ACGT characters for whole 6 lines

If the input is multi-line and you have to match your regexp against the full input (all lines concatenated), then you should strip off the newlines characters of each individual line:

while($line = <IN>)
{
   chomp $line;  ## <---- !!!
   $text .= $line;
}