euidaccess(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

EUIDACCESS(3)           Linux Programmer's Manual          EUIDACCESS(3)

NAME         top

       euidaccess, eaccess - check effective user's permissions for a
       file

SYNOPSIS         top

       #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         top

       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         top

       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.

ERRORS         top

       As for access(2).

VERSIONS         top

       The eaccess() function was added to glibc in version 2.4.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             Attribute     Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │euidaccess(), eaccess()               │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO         top

       These functions are nonstandard.  Some other systems have an
       eaccess() function.

NOTES         top

       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         top

       access(2), chmod(2), chown(2), faccessat(2), open(2), setgid(2),
       setuid(2), stat(2), credentials(7), path_resolution(7)

COLOPHON         top

       This page is part of release 5.13 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/.

                               2021-03-22                  EUIDACCESS(3)

Pages that refer to this page: access(2)credentials(7)