Number of days in git project per user.

git-user-activity.sh

# number of days beetween first and last commit by user
mapfile -t authors < <( git log --pretty=format:%an | sort | uniq )
echo "Number of authors:" ${#authors[@]}

for author in "${authors[@]}"
do
  lastCommitDate=`git log --pretty=format:%at --author="$author" | sed -n 1p`
  firstCommitDate=`git log --pretty=format:%at --author="$author" | tail -1`
  
  if [ ! -z "$lastCommitDate" ]; 
  then
    daysInProject=$((($lastCommitDate - $firstCommitDate)/60/60/24))	
    echo $author"	"$daysInProject
  fi

done