Dear Summit,

thank you so much for replying me i really appreciate you
but please can you expalin me this
{sum[$1,$2,$3]+=$4}
what does this mean in array coz my array concept is weak and the other thing i want to store only 3rd field but in your case it seems to be stored 1,2,3 fileds right .
the data might be 1000 line in my text file so please can you brief it out your command
awk -F, '{sum[$1,$2,$3]+=$4} END {for (i in sum) print i, sum[i]}' data.

Regards,
Shary