$
$ # Current week is from Monday, 5/13/2013 to Sunday, 5/19/2013
$ cat input.txt
2013-05-11 09:10:11 bacha Blah 524gps
2013-05-13 08:20:02 bacha Blah 524gps
2013-05-13 08:30:02 guppy blah 125gps
2013-05-13 12:10:02 mojarra blah 104gps
2013-05-13 13:59:01 longfin blah 105gps
2013-05-14 20:21:22 longfin blah 105gps
2013-05-19 22:23:24 longfin blah 105gps
2013-05-20 09:45:59 longfin blah 105gps
$
$
$ ##
$ perl -lne 'BEGIN {
               use Time::Local 'timelocal_nocheck';
               @x = localtime;
               if ($x[6] == 0) { $sdow = $x[7] - 5;         $edow = $x[7] + 2         }
               else            { $sdow = $x[7] - $x[6] + 2; $edow = $x[7] - $x[6] + 8 }
               @s = localtime timelocal_nocheck 0,0,0,$sdow,0,(1900+$x[5]);
               $s[5] += 1900; $s[4]++;
               $sow = sprintf("%4d%02d%02d",$s[5],$s[4],$s[3]);
               @e = localtime timelocal_nocheck 59,59,23,$edow,0,(1900+$x[5]);
               $e[5] += 1900; $e[4]++;
               $eow = sprintf("%4d%02d%02d",$e[5],$e[4],$e[3]);
             }
             ($y, $mn, $d, $h, $mi, $s, $name) = m/^(\d+)-(\d+)-(\d+)\s+(\d+):(\d+):(\d+)\s+(\w+).*/;
             $curr_dt = sprintf("%4d%02d%02d",$y,$mn,$d);
             if ($sow <= $curr_dt and $curr_dt <= $eow) { $occurrences{$name}++ }
             END {
               while (($k, $v) = each %occurrences) {
                 print "Name : $k\tNo. of occurrences = $v";
               }
             }
            ' input.txt
Name : longfin  No. of occurrences = 3
Name : mojarra  No. of occurrences = 1
Name : bacha    No. of occurrences = 1
Name : guppy    No. of occurrences = 1
$
$