geteuid32 (2) Linux Manual Page
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, POSIX.1-2008, 4.3BSD.Notes
History
In UNIX V6 the getuid() call returned (euid << 8) + uid. UNIX V7 introduced separate calls getuid() and geteuid().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 kernel versions.
On Alpha, instead of a pair of getuid() and geteuid() system calls, a single getxuid() system call is provided, which returns a pair of real and effective UIDs. The glibc getuid() and geteuid() wrapper functions transparently deal with this. See syscall(2) for details regarding register mapping.