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.\"     @(#)getuid.2	8.1 (Berkeley) 6/4/93
.\" %FreeBSD: src/lib/libc/sys/getuid.2,v 1.12 2002/12/18 09:22:30 ru Exp %
.\"
.\" $FreeBSD$
.Dd June 4, 1993
.Dt GETUID 2
.Os
.Sh 名称
.Nm getuid ,
.Nm geteuid
.Nd ユーザ識別子を得る
.Sh ライブラリ
.Lb libc
.Sh 書式
.In unistd.h
.In sys/types.h
.Ft uid_t
.Fn getuid void
.Ft uid_t
.Fn geteuid void
.Sh 解説
.Fn getuid
システムコールは、呼び出しプロセスの実ユーザ ID を返します。
.Fn geteuid
システムコールは、呼び出しプロセスの実効ユーザ ID を返します。
.Pp
実ユーザ ID は、プログラムを起動したユーザの ID です。
実効ユーザ ID は、
.Dq Em ユーザ ID 設定
モードプロセスの実行中にプロセスに追加のパーミッションを与えるので、
.Fn getuid
を使用して呼び出しプロセスの実ユーザ ID を把握します。
.Sh エラー
.Fn getuid
システムコールと
.Fn geteuid
システムコールは必ず正常に完了するので、エラーを示すための戻り値はありません。
.Sh 関連項目
.Xr getgid 2 ,
.Xr issetugid 2 ,
.Xr setgid 2 ,
.Xr setreuid 2 ,
.Xr setuid 2
.Sh 規格
.Fn geteuid
システムコールと
.Fn getuid
システムコールは
.St -p1003.1-90
に適合しています。
.Sh 歴史
.Fn getuid
関数と
.Fn geteuid
関数は
.At v7
ではじめて登場しました。