_POSIX_C_SOURCE    20 src/dps8/dps8_duma.h # ifndef _POSIX_C_SOURCE
_POSIX_C_SOURCE    48 src/simh/linehistory.c #ifndef _POSIX_C_SOURCE
_POSIX_C_SOURCE    48 src/simh/linehistory.h #ifndef _POSIX_C_SOURCE