EUIDACCESS
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME
euidaccess, eaccess - check effective user's permissions for a file
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>
int euidaccess(const char *pathname, int mode);
int eaccess(const char *pathname, int mode);
DESCRIPTION
Like
access(2),
euidaccess()
checks permissions and existence of the file identified by its argument
pathname.
However, whereas
access(2)
performs checks using the real user and group identifiers of the process,
euidaccess()
uses the effective identifiers.
mode
is a mask consisting of one or more of
R_OK, W_OK, X_OK, and F_OK,
with the same meanings as for
access(2).
eaccess()
is a synonym for
euidaccess(),
provided for compatibility with some other systems.
RETURN VALUE
On success (all requested permissions granted), zero is returned.
On error (at least one bit in
mode
asked for a permission that is denied, or some other error occurred),
-1 is returned, and
errno
is set appropriately.
ERRORS
As for
access(2).
VERSIONS
The
eaccess()
function was added to glibc in version 2.4.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
euidaccess(),
eaccess()
| Thread safety | MT-Safe
|
CONFORMING TO
These functions are nonstandard.
Some other systems have an
eaccess()
function.
NOTES
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.
This function always dereferences symbolic links.
If you need to check the permissions on a symbolic link, use
faccessat(2)
with the flags
AT_EACCESS
and
AT_SYMLINK_NOFOLLOW.
SEE ALSO
access(2),
chmod(2),
chown(2),
faccessat(2),
open(2),
setgid(2),
setuid(2),
stat(2),
credentials(7),
path_resolution(7)
COLOPHON
This page is part of release 4.13 of the Linux
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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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