GETUID(2) BSD Programmer's Manual GETUID(2)
getuid, geteuid - get user identification
#include <sys/types.h> #include <unistd.h> uid_t getuid(void); uid_t geteuid(void);
The getuid() function returns the real user ID of the calling process. The geteuid() function returns the effective user ID of the calling pro- cess. The real user ID is that of the user who has invoked the program. As the effective user ID gives the process additional permissions during execu- tion of "set-user-ID" mode processes, getuid() is used to determine the real user ID of the calling process.
The getuid() and geteuid() functions are always successful, and no return value is reserved to indicate an error.
getgid(2), setreuid(2), setuid(2)
The getuid() and geteuid() functions conform to IEEE Std 1003.1-1988 ("POSIX.1"). MirBSD #10-current June 4, 1993 1