On 27 Dec 2016 11:23, Paul Eggert wrote: > Thanks for reporting that problem. I wonder why GNU 'make' sets stdout to > append > mode? That surprises me, and I don't see where POSIX allows it. Anyway, it's > clearly a bug in 'grep' no matter what 'make' is doing. I wrote up a test > case > for the bug and installed the attached, which is a bit more conservative than > the patch you submitted.
fwiw, this patch also fixes misbehavior when stdout & stderr are the same fd.
i mention it only because the NEWS entry was documenting different cases the
failure could come up.
this fails:
(make -v | grep .) >/dev/null 2>&1
but this works:
(make -v | grep .) >/dev/null 2>/dev/null
stracing shows same issue:
splice(0, NULL, 1, NULL, 32768, SPLICE_F_MOVE) = -1 EINVAL (Invalid argument)
write(2, "/bin/grep: ", 11) = 11
write(2, "(standard input)", 16) = 16
write(2, ": Invalid argument", 18) = 18
write(2, "\n", 1) = 1
close(1) = 0
close(2) = 0
exit_group(2) = ?
-mike
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