add or change extension of files

add .udf to all files in working directory

for i in `ls`; do mv $i $i".udf"; done

change extensions of files to "zip".

#new extension: zip
yeniUzanti="zip"; for i in `ls`; do noktalar=`echo $i|awk -F. '{ print NF - 1 }'`; dosyaAdi=`echo $i|cut -d'.' -f1-$noktalar`; mv $i $dosyaAdi"."$yeniUzanti; done