eaccess

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

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  appro-
       priately.

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 at-
       tributes(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), se-
       tuid(2), stat(2), credentials(7), path_resolution(7)

COLOPHON
       This page is part of release 5.05 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/.

                                  2017-09-15                     EUIDACCESS(3)