Implement persistent counter

Question

I want to create a sort of counter that is persistent but I don't want to use the database for that (no other reason but I prefer to avoid creating a table for just having a counter which I won't need in a few months anyway).
So my problem is that I want to count how many times I do something in a function but when the script re-runs I want to increment the existing count.
I thought to create a file and just add the count to the file and update the file but I thought perhaps there is an abstraction ready to use for something like this.

Answer 1

If you're not using counter in concurrent environment,

use strict;
use warnings;

sub increment {
  my ($file) = @_;
  open my $fh, "+>>", $file or die $!;

  seek($fh, 0, 0);
  my $count = <$fh> // 0;
  seek($fh, 0, 0);
  truncate($fh, 0);

  print $fh ++$count;      
  close $fh or die $!;

  return $count;
}

my $current_count = increment("/tmp/counter");