euidaccess, eaccess - check effective user's permissions for a file
Standard C library (
libc,
-lc)
#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);
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.
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 to indicate the
error.
As for
access(2).
The
eaccess() function was added in glibc 2.4.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
euidaccess (), eaccess () |
Thread safety |
MT-Safe |
These functions are nonstandard. Some other systems have an
eaccess()
function.
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.
access(2),
chmod(2),
chown(2),
faccessat(2),
open(2),
setgid(2),
setuid(2),
stat(2),
credentials(7),
path_resolution(7)