envp.c

/*
  on Unix the 'main' function in C can also take a 3rd argument, a pointer to the current environment variables.
  https://www.gnu.org/software/libc/manual/html_node/Program-Arguments.html
  Via: https://twitter.com/deech/status/892938689927630848
  gcc envp.c -o prog
*/

#include <stdio.h>

int main(int argc, char *argv[], char *envp[])
{
  for (size_t i = 0; i < sizeof(envp); i++)
  {
    printf("%s\n", envp[i]);
  }
}

output

AWS_HOME=/Users/pgowda/.aws
Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.V28Aqn6H4u/Render
CAML_LD_LIBRARY_PATH=/Users/pgowda/.opam/4.02.3/lib/stublibs
DBUS_LAUNCHD_SESSION_BUS_SOCKET=/private/tmp/com.apple.launchd.TyY5jooP1f/unix_domain_listener
DISPLAY=/private/tmp/com.apple.launchd.TfvbOMunNM/org.macosforge.xquartz:0
GEM_HOME=/Users/pgowda/.rvm/gems/ruby-2.2.2