GETUID
Section: Linux Programmer's Manual (2)
Updated: 2019-03-06
Page Index
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, 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.
SEE ALSO
getresuid(2),
setreuid(2),
setuid(2),
credentials(7)
COLOPHON
This page is part of release 5.10 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.