#!/path/to/perl
use strict;
use warnings;
use IO::File;

my $write_fh = IO::File->new( 'sample.log', 'w' );
my $read_fh = IO::File->new( 'sample.log', 'r' );

$write_fh->print( "line1\n" );
$write_fh->print( "line2\n" );
$write_fh->print( "line3\n" );

system( 'cat sample.log' );

while( <$read_fh> ) {
    chomp;
    print "[$_]\n";
}