use strict;
use warnings;

# Initialise file names and open files, one
# for reading, two for writing.
#
my $inputFile  = q{spw579580.inp};
my $headerFile = q{spw579580.hdrs};
my $detailFile = q{spw579580.dets};

open my $inputFH, q{<}, $inputFile
   or die qq{open: $inputFile: $!\n};
open my $headerFH, q{>}, $headerFile
   or die qq{open: $headerFile: $!\n};
open my $detailFH, q{>}, $detailFile
   or die qq{open: $detailFile: $!\n};

# Set up start and end sentinels.
#
my $startSentinel = q{^L};
my $endSentinel   = q{EOE};

# Compile regex to pull out records. Note the
# \Q ... \E to quote regex metacharacters if your
# record start and stop sentinels contain them.
#
my $rxExtractRecord = qr
   {(?xms)
      \Q$startSentinel\E\n
      (.*?)
      (?=\Q$endSentinel\E\n|\z)
   };

# Slurp whole file into string.
#
my $completeFile;
{
    local $/;
    $completeFile = <$inputFH>
}

# Do a global match against compiled regex to
# pull out records and put them in an array. They
# will have the start and end record sentinels
# removed by this process.
#
my @records = $completeFile =~ m{$rxExtractRecord}g;

# Process each record in a loop.
#
foreach my $record (@records)
{
    # We now have the record in a scalar
    # variable $record ready for processing.
    #

    # FURTHER PROCESSING GOES HERE ...
}

# Close open filehandles.
#
close $inputFH
   or die qq{close: $inputFile: $!\n};
close $headerFH
   or die qq{close: $headerFile: $!\n};
close $detailFH
   or die qq{close: $detailFile: $!\n};