clang -O2  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_POSIX2_FORT_RUN.c -o unistd/_POSIX2_FORT_RUN -D_POSIX_C_SOURCE=202405L  -lm  -lintl
unistd/_POSIX2_FORT_RUN.c:4:2: error: "_POSIX2_FORT_RUN is not defined"
#error "_POSIX2_FORT_RUN is not defined"
 ^
1 error generated.