That caching is pretty much free with only one exception: it might evict other cached pages. > When I grep through the odd multi-GB file I sometimes/often don'

That caching is pretty much free with only one exception: it might evict other cached pages. > When I grep through the odd multi-GB file I sometimes/often don't want that to be cached. What are you hoping to gain here? The only place I could imagine this might be an issue is on a HDD-using (as opposed to SSD) server that serves a lot of files, which you might evict with your grepping, causing a lot of random IO activity later because the server needs to read everything from disk again to serve requests. But as a "odd" one-off I probably just wouldn't care.