Shell Programming and Scripting

Hello all,

I have some weird problem that kinda baffles me. Say I have the following test file:

Code:

claudia:~/tmp$ cat testfile.txt
This is a test line
This is the second test line
And yeah, this is the third test line

Then say I want to tail the file, grep for the word "third" then display only the 7th field. I would do some like this:

Code:

claudia:~/tmp$ tail -f testfile.txt | grep third | cut -d\  -f7

However, that does not work. I get no error, but no output either. If I leave out the "cut" part, then the grep works fine:

Code:

claudia:~/tmp$ tail -f testfile.txt | grep third
And yeah, this is the third test line

If I do the same with "cat" then it works fine, the expected output appears:

Code:

claudia:~/tmp$ cat testfile.txt | grep third | cut -d\  -f7
test

What am I doing wrong ?

Thanks,
Sylaan