.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.TH EUIDACCESS 3 2017-09-15 "" "Linux Programmer's Manual"
.SH NAME
euidaccess, eaccess \- check effective user's permissions for a file
.SH SYNOPSIS
.nf
.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
.B #include <unistd.h>
.PP
.BI "int euidaccess(const char *" pathname ", int " mode );
.BI "int eaccess(const char *" pathname ", int " mode );
.fi
.SH DESCRIPTION
Like
.BR access (2),
.BR euidaccess ()
checks permissions and existence of the file identified by its argument
.IR pathname .
However, whereas
.BR access (2)
performs checks using the real user and group identifiers of the process,
.BR euidaccess ()
uses the effective identifiers.
.PP
.I mode
is a mask consisting of one or more of
.BR R_OK ", " W_OK ", " X_OK ", and " F_OK ,
with the same meanings as for
.BR access (2).
.PP
.BR eaccess ()
is a synonym for
.BR euidaccess (),
provided for compatibility with some other systems.
.SH RETURN VALUE
On success (all requested permissions granted), zero is returned.
On error (at least one bit in
.I mode
asked for a permission that is denied, or some other error occurred),
\-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
As for
.BR access (2).
.SH VERSIONS
The
.BR eaccess ()
function was added to glibc in version 2.4.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw23 lb lb
l l l.
Interface	Attribute	Value
T{
.BR euidaccess (),
.BR eaccess ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
These functions are nonstandard.
Some other systems have an
.\" e.g., FreeBSD 6.1.
.BR eaccess ()
function.
.SH NOTES
.IR Warning :
Using this function to check a process's permissions on a file before
performing some operation based on that information leads to race conditions:
the file permissions may change between the two steps.
Generally, it is safer just to attempt the desired operation and handle
any permission error that occurs.
.PP
This function always dereferences symbolic links.
If you need to check the permissions on a symbolic link, use
.BR faccessat (2)
with the flags
.BR AT_EACCESS
and
.BR AT_SYMLINK_NOFOLLOW .
.SH SEE ALSO
.BR access (2),
.BR chmod (2),
.BR chown (2),
.BR faccessat (2),
.BR open (2),
.BR setgid (2),
.BR setuid (2),
.BR stat (2),
.BR credentials (7),
.BR path_resolution (7)
.SH COLOPHON
This page is part of release 4.16 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.