freebsd man page for getuid

GETUID(2)						      BSD System Calls Manual							 GETUID(2)

NAME
     getuid, geteuid -- get user identification

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>
     #include <sys/types.h>

     uid_t
     getuid(void);

     uid_t
     geteuid(void);

DESCRIPTION
     The getuid() system call returns the real user ID of the calling process.	The geteuid() system call returns the effective user ID of the
     calling process.

     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
     execution of ``set-user-ID'' mode processes, getuid() is used to determine the real-user-id of the calling process.

ERRORS
     The getuid() and geteuid() system calls are always successful, and no return value is reserved to indicate an error.

SEE ALSO
     getgid(2), issetugid(2), setgid(2), setreuid(2), setuid(2)

STANDARDS
     The geteuid() and getuid() system calls are expected to conform to ISO/IEC 9945-1:1990 (``POSIX.1'').

HISTORY
     The getuid() and geteuid() functions appeared in Version 7 AT&T UNIX.

BSD
								   June 4, 1993 							       BSD