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GETUID(2) 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.
December 1, 2017 Linux 4.19.0-6-amd64