getuid man 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.

See Also

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

Colophon

This page is part of release 4.08 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/.

Referenced By

credentials(7), gawk(1), getlogin(3), getresuid(2), lockfile-progs(1), mksh(1), oping(8), pam_close_session(3), pam_open_session(3), procenv(1), ps(1), seteuid(2), setpgid(2), setresuid(2), setreuid(2), setuid(2), syscalls(2), user_namespaces(7).

geteuid(2) and getuid32(2) are aliases of getuid(2).

2015-08-08 Linux Linux Programmer's Manual