Question

How can I open STDIN for the second time?

Let say I have this data

John Smith  25  O   ATG 180
Peter Jackson   40  AB  GGTA    173
Carl Anderson   32  A   GGT 172

And I have this code

while( my $line = <>)  {
    print $line;
}
while( my $line = <>)  {
    print $line;
}

I want it to print

John Smith  25  O   ATG 180
Peter Jackson   40  AB  GGTA    173
Carl Anderson   32  A   GGT 172
John Smith  25  O   ATG 180
Peter Jackson   40  AB  GGTA    173
Carl Anderson   32  A   GGT 172

Answer 1

You can’t, you have emptied the stream. If you want to use it again, put the lines in an array.

my @lines;
while( my $line = <>)  {
    print $line;
    push @lines, line;
}

foreach my $line (@lines)  {
    print $line;
}

Or, write to a file and get a filehandle on the file.