cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration spawn/posix_spawn.c -o spawn/posix_spawn -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
spawn/posix_spawn.c:6:10: fatal error: spawn.h: No such file or directory
    6 | #include <spawn.h>
      |          ^~~~~~~~~
compilation terminated.