Rename all files in directory from $file to $newfile

Dead simple.
How do I rename

hello_kitty2.png
hello_kitty3.png

1 2	hello_kitty2.png hello_kitty3.png

byebye_kitty2.png
byebye_kitty3.png

1 2	byebye_kitty2.png byebye_kitty3.png

I think it’s simple, but it’s hard to Google for this kind of thing unless you already know.

You can do this with a simple one-liner with bash

for file in $(ls hello_ki*); do mv "$file" "${file/hello/byebye}"; done

1	for file in $(ls hello_ki*); do mv "$file" "${file/hello/byebye}"; done