convertToWebp.sh

#!/bin/bash

strExt="png"

function FUNCconv() {
  local lstrFile="$1"
  lstrFileWebp="${lstrFile%.$strExt}.webp"
  if [[ ! -f "$lstrFileWebp" ]];then
    echo
    echo ">>> working with $lstrFile <-> $lstrFileWebp"
    cwebp -q 80 "$lstrFile" -o "$lstrFileWebp"
    ls -l "$lstrFile" "$lstrFileWebp"
  else
    echo ">>> found $lstrFileWebp"
  fi
};export -f FUNCconv

find ./ -iname "*.${strExt}" -exec bash -c "FUNCconv '{}'" \;