cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration signal/sig2str.c -o signal/sig2str -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
signal/sig2str.c:9:12: error: use of undeclared identifier 'SIG2STR_MAX'
    9 |         char name[SIG2STR_MAX];
      |                   ^
signal/sig2str.c:10:7: error: call to undeclared function 'sig2str'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   10 |         if ( sig2str(SIGUSR1, name) < 0 )
      |              ^
2 errors generated.