Git insertions and deletions

git-inserts-deletes.sh

git log --shortstat --format="%an" | sed '/^$/d' | awk '
BEGIN { FS = ", " }
{
  if (match($1, /^ [0-9]+ files? changed/)) {
    split($2, a, " ")
    inserts = (a[1] == "")? 0 : a[1]
    split($3, b, " ")
    deletes = (b[1] == "")? 0 : b[1]
    total = (inserts - deletes)
    print name " " inserts " " deletes " " total
  } else {
    name = $0
  }
}' | sort | awk '
{
  name = $1
  for (i = 2; i <= (NF - 3); i++) {
    name = name " " $i
  }
  if (name == previous) {
    inserts = inserts + $(NF - 2)
    deletes = deletes + $(NF - 1)
    total = total + $NF
  } else if (previous != "") {
    print total ", " previous ", " inserts ", " deletes ", " total
    grandTotal = grandTotal + total
    inserts = $(NF - 2)
    deletes = $(NF - 1)
    total = $NF
  }
  previous = name
}
END {
  print grandTotal ", Total, -, -," grandTotal
}
' | sort -rn | cut -d " " -f 2- | column -t -s,

This version doesn't quite work properly. I get different totals for three different commands:

git ls-files | xargs wc -l
git summary —line
./git-inserts-deletions.sh