Re: D_GNU_SOURCE option for gcc?

[Martin Dickopp <martin-deb@zero-based.org>]

"Thomas H. George" <xyz@spininternet.com> writes:

> I am using source code from UNIX SYSTEMS PROGRAMMING by Robbins &
> Robbins.  It gives a compiler error unless compiled with the option
> -D_GNU_SOURCE .
> Where does this option come from - its not in the man pages?

It defines the preprocessor macro _GNU_SOURCE. If this macro is defined,
the standard library headers adhere to certain standards and enable
GNU extensions. See the comments at the top of /usr/include/features.h
for how to make the standard library adhere to various standards.


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