getnum(){
  ls "$1" | grep "$2$"
}

getnum() {
 ls "$1" | grep "$s$" | cut -d_ -f 2
}

getnum() {
  ls "$1" | grep "$s$" | cut -d_ -f 2 | sort -n
}

getnum() {
  ls "$1" | grep "$s$" | cut -d_ -f 2 | sort -n | head -1
 }

getnum() {
      local oldnum=$(ls "$1" | grep "$s$" | cut -d_ -f 2 | sort -n | head -1)
}

getnum() {
  local oldnum=$(ls "$1" | grep "$s$" | cut -d_ -f 2 | sort -n | head -1)
  if [ "$oldnum" = "" ]
  then
      oldnum=0
  fi
  printf "%02dn" $(($oldnum+1))
 }

dir=somewhere/logs
  ext=testfile.json
  cp template $dir/$(date +%Y%m%d_)$(getnum "$dir" "$ext")_$USER_$ext