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   IPC::Cmd::Cached 0.01
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NAME
   IPC::Cmd::Cached - Run expensive commands and cache their output

SYNOPSIS
       use IPC::Cmd::Cached;

       my $runner = IPC::Cmd::Cached->new();

         # takes a fair mount to run, but result gets cached
       my($success, $error_code, $full_buf, $stdout_buf, $stderr_buf) =
         $runner->run(command => "find /etc -type f -print");

         # Returns the same result much faster, because it's cached
       my($success, $error_code, $full_buf, $stdout_buf, $stderr_buf) =
         $runner->run_cached("find /etc -type f -print");

         # To make sure the cached entries don't expire, run this
         # twice a day via a cronjob:
       $runner->run_all();

DESCRIPTION
   "IPC::Cmd::Cached" uses "IPC::Cmd" to run arbitrary shell commands, but
   caches their results and finds them later.

   It uses a "Cache::FileCache" object to store the output of commands it
   has successfully executed persistently on disk. Results are store under
   a key equal to the command line given to run the commands.

   If a command's output doesn't change much over time and cached results
   are acceptable, "IPC::Cmd::Cached" saves time by reusing canned results
   instead of recalculating the same results over and over again.

   "IPC::Cmd::Cached" works like the "Memoize" module, but instead of
   caching the output of functions, it caches the output of external
   scripts.

CAVEATS
   A command's results are cached based on its full command line. This
   might not be desirable if the same command produces varying output over
   time:

       $ eg/run-cached date
       Mon Dec 17 00:01:00 PST 2007
       $ eg/run-cached -c date
       Mon Dec 17 00:01:00 PST 2007

Advanced use cases
   The constructor accepts arguments to change the runner's internal
   behavior:

   cache
       By default, this is set to a Cache::FileCache object in the default
       namespace with 24 hours of expiration time:

           my $runner = IPC::Cmd::Cached->new(
             cache => Cache::FileCache->new({
               auto_purge_on_get  => 1,
               default_expires_in => 24*3600,
               namespace          => "IPC-Cmd-Cached",
             }),
           );

       If you need different characteristics, define your own cache object
       and hand it over to "new" as shown above. Take a look at the
       Cache::Cache documentation for details.

EXAMPLES
   The distribution comes with two utility scripts, "run-cached" and
   "run-cached-all".

   "run-cached" runs a command specified on its command line. With the -c
   option, it will fetch the cached entry instead.

   "run-cached-all" runs all scripts in the cache to refresh their content.

   Check the documentation that comes with these scripts for more details.

LEGALESE
   Copyright 2007 by Mike Schilli, all rights reserved. This program is
   free software, you can redistribute it and/or modify it under the same
   terms as Perl itself.

AUTHOR
   2007, Mike Schilli <[email protected]>

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