---
name: "getuid"
section: "2freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "12.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/geteuid/2freebsd"
---

# getuid(2freebsd)

get user identification

Part of [geteuid(2freebsd)](/geteuid/2freebsd.md).

## 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)](/getgid/2.md), [issetugid(2)](/issetugid/2.md), [setgid(2)](/setgid/2.md), [setreuid(2)](/setreuid/2.md), [setuid(2)](/setuid/2.md)

## STANDARDS

The **geteuid**() and **getuid**() system calls are expected to conform to ISO/IEC 9945-1:1990 (“POSIX.1”).

## HISTORY

The **getuid**() function appeared in Version 1 AT&T UNIX. The **geteuid**() function appeared in Version 4 AT&T UNIX.