cat venky338.file2

ord,line,Date,Hour,count,appr
1217,1,11/19/2015,"00",8,""
1217,1,11/19/2015,"08",4,""
1217,1,11/19/2015,"10",62,""
1217,1,11/19/2015,"09",20,""
1217,1,11/19/2015,"00",24,""
1217,1,11/19/2015,"10",42,""

perl -anlF"," -e '$.==1?{print}:{@{$r{join ",", @F[0,1,2,3]}}[0]+=$F[4]}; END{$,=",";for(sort keys %r){print $_,$r{$_}[0],qq("")}}' venky338.file2

perl -nle '/(.+,)(.+,.+)/;$.==1?{print}:{@{$r{$1}}[0]+=$2}; END{for(sort keys %r){print "$_$r{$_}[0],\"\""}}' venky338.file2

ord,line,Date,Hour,count,appr
1217,1,11/19/2015,"00",32,""
1217,1,11/19/2015,"08",4,""
1217,1,11/19/2015,"09",20,""
1217,1,11/19/2015,"10",104,""

perl # Perl binary
-nle # equivalent to -n -l -e
-n # loop through each line of the file
-l # remove the newline and append it to any print
-e # process the following as Perl code

/(.+,)(.+,.+)/; # divide the line into an identification token and a portion that needs to be added

$.==1?{print}:{@{$r{$1}}[0]+=$2}; # if it is the first line just print it otherwise use the first token as the key of a hash and add the second token as its value

END{for(sort keys %r){print "$_$r{$_}[0],\"\""}} # sort and display every unique record