When I have both Red Hat Linux/Intel 5.2 and 6.0 installed on
different machine, I noticed
that the file /usr/include/sys/errno.h is corrupted. It contains
only one line inside:
errno.h should include all the error numbers and its definition.
As far as I can tell, there is nothing wrong with it. sys/errno.h
includes errno.h, that includes bits/errno.h, which in turn includes
linux/errno.h ... Okey, it's a mess, but you get what you need.
/usr/include/errno.h which includes
/usr/include/bits/errno.h which includes
/usr/include/linux/errno.h which contains the error code numbers.
The second person's response is correct.