# ABSTRACT: Open a file, read a number value, increment it, save the file
# For the sake of simplicity, this code assumes:
#   * the counter file already exist and is writeable
#   * the counter file has one line, which contains only numbers
use strict; # always
use warnings;
use File::Util;
my $ftl = File::Util->new();
my $counterfile = 'counter.txt'; # the counter file needs to already exist
my $count = $ftl->load_file( $counterfile );
# convert textual number to in-memory int type, -this will default
# to a zero if it encounters non-numerical or empty content
chomp $count;
$count = int $count;
print "Count value from file: $count.";
$count++; # increment the counter value by 1
# save the incremented count back to the counter file
$ftl->write_file( filename => $counterfile, content => $count );
# verify that it worked
print ' Count is now: ' . $ftl->load_file( $counterfile );
exit;