...d macro is described in the man page. For further information on feature test macros, see feature_test_macros (7). Subsections Section 3 of this manual is organized into subsect…...e <unistd.h> int group_member(gid_t gid ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): group_member (): _GNU_SOURCE DESCRIPTION The group_member () …...ALSO kill (2), sigaction (2), sigprocmask (2), sigsuspend (2), sigblock (3), sigvec (3), feature_test_macros (7)...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...reater( x , y ); int isunordered( x , y ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): All functions described here: _ISOC99_SOURCE || _POSIX_C_SOUR…...rmal( x ); int isnan( x ); int isinf( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fpclassify (), isfinite (), isnormal (): _ISOC99_SOURCE || _P…...rmal( x ); int isnan( x ); int isinf( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fpclassify (), isfinite (), isnormal (): _ISOC99_SOURCE || _P…...rmal( x ); int isnan( x ); int isinf( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fpclassify (), isfinite (), isnormal (): _ISOC99_SOURCE || _P…...rmal( x ); int isnan( x ); int isinf( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fpclassify (), isfinite (), isnormal (): _ISOC99_SOURCE || _P…...rmal( x ); int isnan( x ); int isinf( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fpclassify (), isfinite (), isnormal (): _ISOC99_SOURCE || _P…...nt whence ); off_t ftello(FILE * stream ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fseeko (), ftello (): _FILE_OFFSET_BITS == 64 || _POSIX_C_SOU…...nt whence ); off_t ftello(FILE * stream ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): fseeko (), ftello (): _FILE_OFFSET_BITS == 64 || _POSIX_C_SOU…...memory area LIBRARY Standard C library ( libc , -lc ) SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <string.h> void *mempcpy(void dest [restrict . n ], …...memory area LIBRARY Standard C library ( libc , -lc ) SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <string.h> void *mempcpy(void dest [restrict . n ], …...NOPSIS #include <math.h> int signbit( x ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): signbit (): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L DESC…...restrict dst , const char *restrict src ); Feature Test Macro Requirements for glibc (see feature_test_macros (7)): stpcpy (): Since glibc 2.10: _POSIX_C_SOURCE >= 200809L Befor…