Actually grep was intended as a trivial example of something someone might run in exec after forking with reference to a FD that the parent opened. We don't actually need to grep the passwd file, I just wanted a simple example to show what was not working for us. $^F was the solution.

In reply to Re^2: Leaking a file descriptor into a child to use with /proc/self/fd/3 by ewheeler
in thread Leaking a file descriptor into a child to use with /proc/self/fd/3 by ewheeler

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