zmv -n '()_()' '${1}1_$2

-n print instead of doing operation

-Q search for hidden files also

zmv -Q '(**/)(*).txt' '$1$2.rtf

(**/) search in subfolders

c=1 zmv '*.txt' '$((c++)).txt'

rename all files with a number incrementing from 1

add number to existing file name number

c=170 zmv '()_().png' '$(($c+$1))_$2.png'