Should have clarified.. It's a yes to both, all the snaps are identical on all the systems (name, date etc.). I'm just getting to grips with Perl so I'm going to play with the suggestions (it might take me a while though :-) ). Thanks.

So that makes your problem really easy (untested code):

$isok = 1;
for $logname("logfile1", "logfile2", "logfile3")
{
  open FH, $logname ...;
  @isthisfileok=(0)x 6;
  while(<FH>)
  {
    $isthisfileok[$1]++ if /^snapshot([1-6])/;
    # last if /^snapshot([7-9]|\d{2,})/; # are snapshots sorted numeri
+cally? then you don't have to search whole file if found snapshot7 or
+ other
  }
  close FH;
  $somesnapshotnotfound = grep $_ == 0, @isthisfileok;
  $isok = 0 if !$somesnapshotnotfound;
  last if !$isok; # don't scan another file if already not ok
}
print "everything ok" if $isok;
[download]

The actual output looks like -

NAME                                                   
tank/filesystem@hourly-1348093078_2012.10.24.13.30.03 
tank/filesystem@hourly-1348093078_2012.10.24.14.30.01 
tank/filesystem@hourly-1348093078_2012.10.24.15.30.03 
tank/filesystem@hourly-1348093078_2012.10.24.16.30.01 
tank/filesystem@hourly-1348093078_2012.10.24.17.30.02
[download]

They are auto-created every hour and the command outputs them in date order (I can choose earliest or latest first), so using your example I would need to split on the '.' and pick up the date and hour I think