geteuid

   With POSIX IDs disabled, this function is equivalent to getuid
   and returns the member number (in OpenVMS terms) from the user
   identification code (UIC).

   With POSIX IDs enabled, this function returns the effective user
   ID.

   Format

     #include  <unistd.h>

     uid_t geteuid  (void);
 

Additional information available:

Description     Return_Value