open (IN, "< $file")
  or warn ("Can't open $file: $!\n"), die;

while (<IN>) {               # loop through the file,
  print ("$file ==> $_");    # read one line at a time
}

close(IN);

##</code><code>##

open (IN, "< $file")
  or warn ("Can't open $file: $!\n"), die;

chomp(my @data = <IN>);      # read all lines into array of lines
                             # and get rid of trailing \n's

print "$_\n" for @data;

close(IN);

##</code><code>##

open (IN, "< $file")
  or warn ("Can't open $file: $!\n"), die;

my $data = do { local $/; <IN> };  # file slurping

print ("$file ==> $data\n");

close(IN);