How to clear a text file from lines that do not contain certain characters?

Question

Text Processing Automation

Hello. In the file, each line must contain "yandex" or "google". If it doesn't, then delete the line. How to do this?

Answer 1

notepad++
How to delete lines through bookmarks
1. Menu -> Search -> Marks -> [enter what we are looking for] -> Bookmark (check the box) -> Mark all
2. Menu -> Search -> Bookmarks -> Delete all lines No bookmark
PS: [enter what we are looking for] - you can enable regex expressions and enter:yandex|google

Answer 2

Bash/Cygwin:
grep -E -v "(yandex|google)" < in.txt > out.txt