Split file names into year and month folder

Split-FileNamesByYearMonth.sh

for file in *; do 
    echo $file; 
    yearmonth=$(echo $file | grep -o '[0-9][0-9][0-9][0-9]-[0-9][0-9]')
    newfilename=$(echo $file | grep -o '[0-9][0-9]-[a-z].*.md$')
    mkdir $yearmonth
    mv $file $yearmonth/$newfilename
done