How to invert a grep expression

grep -v

or

grep --invert-match

You can also do the same thing using find:

find . -type f \( -iname "*" ! -iname ".exe" ! -iname ".html"\)

More info here.

Use command-line option -v or --invert-match,

ls -R |grep -v -E .*[\.exe]$\|.*[\.html]$