cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration unistd/setregid.c -o unistd/setregid -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
unistd/setregid.c: In function ‘main’:
unistd/setregid.c:12:14: error: implicit declaration of function ‘setregid’; did you mean ‘setegid’? [-Wimplicit-function-declaration]
   12 |         if ( setregid(rgid, egid) < 0 )
      |              ^~~~~~~~
      |              setegid