NAME
getuid — get a
real user ID
SYNOPSIS
#include
<unistd.h>
uid_t getuid(void);
DESCRIPTION
The getuid () function shall return the
real user ID of the calling process. The getuid ()
function shall not modify errno.
RETURN VALUE
The getuid () function shall always be
successful and no return value is reserved to indicate the error.
ERRORS
No errors are defined.
EXAMPLES
Setting the Effective User ID to the Real User ID
The following example sets the effective user ID of the calling process to the real user ID.
#include <unistd.h> ... seteuid(getuid());
APPLICATION USAGE
None.
RATIONALE
In a conforming environment, getuid ()
will always succeed. It is possible for implementations to provide an
extension where a process in a non-conforming environment will not be
associated with a user or group ID. It is recommended that such
implementations return (
uid_t)
-1 and set errno to indicate such an environment; doing so
does not violate this standard, since such an environment is already an
extension.
FUTURE DIRECTIONS
None.
SEE ALSO
getegid(3), geteuid(3), getgid(3), setegid(3), seteuid(3), setgid(3), setregid(3), setreuid(3), setuid(3)
XBD <sys/types.h>, <unistd.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 6
In the SYNOPSIS, the optional include of the <sys/types.h> header is removed.
The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:
- The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications.
Issue 7
POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0175 [511] and XSH/TC2-2008/0176 [897] are applied.