Hello Florian, On Sat, Oct 30, 2010 at 4:08 PM, Florian Lehmann <flo.lehmann@xxxxxxxxxxxxxx> wrote: > Dear all, > > I am using > Linux hobbes 2.6.35-22-generic #35-Ubuntu SMP Sat Oct 16 20:45:36 UTC > 2010 x86_64 GNU/Linux > > with manpages > Version: 3.24-1ubuntu1 > > I was trying to run a simple c-program using the function crypt from > unistd.h > > Tha manpages states to define the macro _XOPEN_SOURCE in order to use > this function. This works fine on a 32-bit Version of Ubuntu 10.10. On > the mentioned 54-bit system the program could not be compiled. > > On those systems you also have to define the macro __USE_XOPEN. > I attached the program. Just compile with > gcc -Wall crypter.c -lcrypt #will not work without __USE_XOPEN > > Thanks a lot and best regards from Ulm, The problem is almost certainly that you didn't define _XOPEN_SOURCE before including *any* header file. See feature_test_macros(7). Reports like yours turn up with reasonable frequency, and clearly this is a very common misunderstanding. I've tried to prevent it by including a reference to feature_test_macros(7) in all pages where feature test macros are used. That reference is always either in the SEE ALSO section or in the SYNOPSIS. Your report makes me reflect further on problem. I've made a change which always places the reference to feature_test_macros(7) in the SYNOPSIS section, to try and help the reader more easily find this piece of information. The change will be in man-pages-3.30. Thanks for your report! MfG aus Muenchen, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
