bash-script-rename-video-files-with-increment-indexes.sh

rename_f()
{
	local nameprefix="$1";
	local fext="$2";
	idx=0;
	for f in *.$fext; do

		((idx++));
		idxstr=$(printf %02d $idx);
		fnameneo="$nameprefix$idxstr.$fext";
		echo -e "File Name Old : $f";
		echo -e "File Name New : $fnameneo";
		echo -e;
		mv "$f" "$fnameneo";
	
	done
}

# example usage
rename_f "Dexter New Blood " "mp4";
rename_f "Dexter New Blood " "srt";