debian man page for getuid

GETUID(2)						     Linux Programmer's Manual							 GETUID(2)

NAME
       getuid, geteuid - get user identity

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

       uid_t getuid(void);
       uid_t geteuid(void);

DESCRIPTION
       getuid() returns the real user ID of the calling process.

       geteuid() returns the effective user ID of the calling process.

ERRORS
       These functions are always successful.

CONFORMING TO
       POSIX.1-2001, 4.3BSD.

NOTES
   History
       In UNIX V6 the getuid() call returned (euid << 8) + uid.  UNIX V7 introduced separate calls getuid() and geteuid().

NOTES
       The  original  Linux  getuid()  and  geteuid()  system  calls supported only 16-bit user IDs.  Subsequently, Linux 2.4 added getuid32() and
       geteuid32(), supporting 32-bit IDs.  The glibc getuid() and geteuid() wrapper functions transparently deal with the variations across  ker-
       nel versions.

SEE ALSO
       getresuid(2), setreuid(2), setuid(2), credentials(7)

COLOPHON
       This  page is part of release 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2010-11-22								 GETUID(2)