如何用awk对重复行的值求和？

awk -F,'
FNR==1{
  print;
  next}
{
  val=$5;
  $5="~";
  a[$0]+=val
}
!b[$0]++{
  c[++count]=$0}
END{
  for(i=1;i<=count;i++){
     sub("~",a[c[i]],c[i]);
     print c[i]}
}' OFS=,Input_file

说明：现在也向上面的代码添加说明.

awk -F,'                         ##Setting field separator as comma here.
FNR==1{                           ##Checking condition if line number is 1 then do following.
  print;                          ##Print the current line.
  next}                           ##next will skip all further statements from here.
{
  val=$5;                         ##Creating a variable named val whose value is 5th field of current line.
  $5="~";                         ##Setting value of 5th field as ~ here to keep all lines same(to create index for array a).
  a[$0]+=val                      ##Creating an array named a whose index is current line and its value is variable val value.
}
!b[$0]++{                         ##Checking if array b whose index is current line its value is NULL then do following.
  c[++count]=$0}                  ##Creating an array named c whose index is variable count increasing value with 1 and value is current line.
END{                              ##Starting END block of awk code here.
  for(i=1;i<=count;i++){          ##Starting a for loop whose value starts from 1 to till value of count variable.
     sub("~",c[i]);       ##Substituting ~ in value of array c(which is actually lines value) with value of SUMMED $5.
     print c[i]}                  ##Printing newly value of array c where $5 is now replaced with its actual value.
}' OFS=,Input_file               ##Setting OFS as comma here and mentioning Input_file name here too.