ccze with `tail -f` and `grep`

[lvillanne-recia]

When I use ccze with tail -f and grep sometimes some lines at the end of the file that should be displayed are not.

For example, with this very simple :

echo "foo" > foo.txt

If I just do a tail -f on it, it works:

$ tail -f foo.txt | ccze -A
foo

If I just do a tail and a grep on it, it works:

$ tail foo.txt | grep "foo" | ccze -A
foo

If I do a tail -f and a grep without ccze it works:

$ tail -f foo.txt | grep "foo"
foo

But if I do a tail -f and a grep with ccze it doesn't work, no line is displayed:

$ tail -f foo.txt | grep "foo" | ccze -A

I've also tested disabling grep colouring, which doesn't change anything:

$ tail -f foo.txt | grep "foo" --color=never | ccze -A

[lvillanne-recia]

I found out what the problem was. It's a buffer problem in grep, just add the --line-buffered argument to grep and it will work :

$ tail -f foo.txt | grep "foo" --color=never --line-buffered | ccze -A
foo 

So the problem had nothing to do with ccze as the same behaviour is reproducible with cat.