Heres another way :)

use strict;
use warnings;

#using three argument for open();
open ( my $output, '>', 'output' ) or die "cannot open file for writin
+g -$!";

#read and print all on one line ;)
print ( $output $_ ) while(<DATA>);

__DATA__
1st line
2nd line
3rd line
4th line

End of file
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