去除文件名中的"PNG":
ls | while read f; do mv "$f" "$(echo $f | sed 's/PNG//g')"; done
重命名为顺序数字:
ls -v | cat -n | while read n f; do mv -n "$f" "$n.ext"; done
ls | cat -n | while read n f; do mv "$f" `printf "%04d.ext" $n`; done # with leading zeros
num=0; for i in *; do mv "$i" "$(printf '%04d' $num).${i#*.}"; ((num++)); done # keep original extension