getuid
Section: System Calls (2)
Updated: 2022-10-30
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NAME
getuid, geteuid - get user identity
LIBRARY
Standard C library
(libc, -lc)
SYNOPSIS
#include <unistd.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
and never modify
errno.
STANDARDS
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)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- ERRORS
-
- STANDARDS
-
- NOTES
-
- History
-
- SEE ALSO
-
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