Problem using `cut` with `tail -f`

Question

I'm trying to follow a log file and want to extract a field from it. I've tried

tail foo.txt | cut -f 5

and this works, but if I try to follow changes via

tail -f foo.txt | cut -f 5

nothing is printed, even when there are changes to the file.

Any suggestions or comments about why this is happening?

Answer 1

BASH FAQ entry #9: "What is buffering? Or, why does my command line produce no output: tail -f logfile | grep 'foo bar' | awk ..."