I can't test this right now, but I suspect you are being misled by buffering. I recall that strace writes to STDERR, which is normally non-buffered. However you are redirecting it to STDOUT (which you have to do to use the pipe) which is buffered. $|=1;before the open is worth a try.

In reply to Re: Calling strace from a perl program by cdarke
in thread Calling strace from a perl program by jason_s

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