How to delete all lines that do NOT contain a certain word in Vim?

You can use

:g!/price/d

to delete every line that doesn't contain "price"

As answered below, g! is an alias to v. this is equivalent to

:v/price/d

You can also use:

:v/price/d

to delete lines.

%!grep "price"

is another option that can be considerably faster than :v for large files.

Tested on Vim 7.4, Ubuntu 14.04, 1M line log file.

Lines that contain word: https://stackoverflow.com/questions/1725265/how-can-i-delete-all-lines-that-do-not-begin-with-certain-characters/42714334#42714334