You could use Inline::Files and store the counter with the script itself.

open I, "<counter.txt"; my $n = <I>; chomp($n); close(I); $n++; open O
+, ">counter.txt"; print O $n; close(O);
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Storable::nstore("file", \$count);
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perl -MFile::Slurp -le 'write_file "tmp42", $n = 1 + eval{read_file "t
+mp42"}; print $n'
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Some experts gave you bad advice. You need to read and update the file as one step, otherwise another process comes along and tries to do the same thing while you are in the middle. Either the count doesn't get incremented properly (both processes read the same value before either one wrote a new one), the count gets reset (one process reads the file just after it was truncated), or the count disappears.

--
brian d foy <brian@stonehenge.com>

I'm a sucker for log files, so I would probably capture the date and time of the program's run, perhaps its arguments (if any) on one line of a log file. Then, I could just run wc -l /logfile for a count, but then I can capture other information as well.

What is "best" purely depends on what you want, and what your wishes are. All solutions are simple, requiring just a few lines of code.

  #!/usr/bin/perl

  use warnings;
  use strict;

  use Config::Properties::Simple;

  my $cfg=Config::Properties::Simple->new(scope=>'user', optional=>1);
  my $count=$cfg->getProperty(counter => 0);

  print "counter: $count\n";

  $cfg->setProperty(counter => ++$count);
  $cfg->save;
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You should also use some lock to ensure that only one process reads and increments the counter.

  use Cache::FileCache;
  my $cache = new Cache::FileCache( { namespace=>"my_program", auto_pu
+rge_on_get=>1 } );
  my $cacheKey = 'ct';
  my $value = $cache->get( $cacheKey ) || 0;
  $value++;
  $cache->set( $cacheKey, $value, $EXPIRES_NEVER );
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    echo $((`cat counter` + 1)) > counter
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    echo $((`cat counter` + 1)) > counter

Which won't work well if there can be multiple instances of the program running at the same time.

I never claimed it was. And it wasn't the first suggestion in this thread that might fail if multiple instances of the program are running at the same time. (Well, technically, having multiple instances of the program running at the same time isn't the problem - the problem is them executing the one line of code at the same time).

Code Pendants question was vague. He just wanted to know what other people used. He didn't state anything specific about his situation. Other than the implicite suggestion the program is started once a day (so, no multiple occurences).

Here's another one-liner you can list faults for:

perl -pi -le '$_++' counter
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