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GETUID(2) FreeBSD System Calls Manual GETUID(2)
NAME
getuid, geteuid - get user identification
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
uid_t
getuid(void);
uid_t
geteuid(void);
DESCRIPTION
The getuid() system call returns the real user ID of the calling process.
The geteuid() system call returns the effective user ID of the calling
process.
The real user ID is that of the user who has invoked the program. As the
effective user ID gives the process additional permissions during
execution of "set-user-ID" mode processes, getuid() is used to determine
the real-user-id of the calling process.
ERRORS
The getuid() and geteuid() system calls are always successful, and no
return value is reserved to indicate an error.
SEE ALSO
getgid(2), issetugid(2), setgid(2), setreuid(2), setuid(2)
STANDARDS
The geteuid() and getuid() system calls are expected to conform to IEEE
Std 1003.1-1990 ("POSIX.1").
HISTORY
The getuid() function appeared in Version 1 AT&T UNIX. The geteuid()
function appeared in Version 4 AT&T UNIX.
FreeBSD 14.0-RELEASE-p6 December 1, 2017 FreeBSD 14.0-RELEASE-p6