2 @section @code{environ}
5 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/environ.html}
9 Portability problems fixed by Gnulib:
12 POSIX does not require this variable to be declared, and it is indeed not
13 declared on some platforms:
14 Mac OS X 10.13, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, IRIX 6.5, Solaris 11.4.
16 On Mac OS X 10, this variable is not declared. Up to Mac OS X 10.4, one can use
18 extern char **environ;
20 to get the variable declared. This does not work any more, however, in
21 shared libraries on Mac OS X 10.13. Here is a workaround: Instead, one can use
23 #include <crt_externs.h>
24 #define environ (*_NSGetEnviron())
26 This works at all versions of Mac OS X.
28 On Cygwin in 64-bit mode, references to this variable cause a link error when
29 the option @code{-Wl,--disable-auto-import} is in use.
32 Portability problems not fixed by Gnulib:
35 The address of this variable is not a compile-time constant on some platforms:
38 Assigning NULL to @code{environ} to clear all variables is not
39 portable; better is to assign @code{environ} to one-element array
40 containing a NULL pointer. That said, an empty environment is not
41 portable either, as some systems may require particular environment
42 variables (such as @code{PATH}) to be present in order to operate