What I've done that covers many of my use cases, is:

  1. Watch & wait for the first type of file to appear.
  2. Sleep for a few seconds to a few minutes depending on the task
  3. Proceed to verify the other matching files exist, and carry on with the task, else loop back to 1

Sometimes the verification is a check to see if the file has grown larger; if so, then it goes back to sleep repeatedly until the download/copy is finished.

For checking the names, you may want to use a regex to capture the relevant part of the filename, and then look for specifically named files using that.

For example, 

if ($file =~ /alphat_(.*)\.zip)
{
  my $key = $1;  # whatever was between alphat_ and the .zip bits.
  if (-f "numerict_${key}.zip && -f "updatet_${key}.zip")
  {
     print "Caught 'em all!\n";
  }  
}

[download]

In reply to Re^3: Check multiple file names exist in directory and create another trigger file after existing files processed by SuicideJunkie
in thread Check multiple file names exist in directory and create another trigger file after existing files processed by vickycanada

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