getuid(2) — Linux manual page


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

NAME         top

       getuid, geteuid - get user identity

SYNOPSIS         top

       #include <unistd.h>

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

DESCRIPTION         top

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

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

ERRORS         top

       These functions are always successful and never modify errno.

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, 4.3BSD.

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 5.13 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

Linux                          2021-03-22                      GETUID(2)

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