if you want file names matching a pattern, no need for grep: find . -name '*.py' -iname '*pattern*' for filenames that have content matching pattern, no need

if you want file names matching a pattern, no need for grep: find . -name '*.py' -iname '*pattern*' for filenames that have content matching pattern, no need for find: grep -r --include '*.py' -l -i pattern . no need for pipes, xargs, etc.