gcc -pthread  -Wall -Wextra -Werror=implicit-function-declaration signal/psignal.c -o signal/psignal -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lxnet -lsocket -latomic
signal/psignal.c: In function 'main':
signal/psignal.c:12:9: error: implicit declaration of function 'psignal'; did you mean 'ssignal'? [-Wimplicit-function-declaration]
   12 |         psignal(SIGUSR1, "foo");
      |         ^~~~~~~
      |         ssignal