Presumably a buffering issue...  (i.e., grep doesn't output anything before its buffer has filled up).

If your grep supports the option, you might want to try 

    ... | grep --line-buffered ...

[download]

(See also Re^2: Reading from a command pipe )

Another solution would be to implement the grepping in Perl, and do away with the system grep altogether.

In reply to Re: Too many pipes? by Eliya
in thread Too many pipes? by kc6ovd

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