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man: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
     attributes(7).
     allbox; lbw23 lb lb l l l.  Interface Attribute Value T{  euidaccess(),
     eaccess() T}   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 4.16 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)
/data/webs/external/dokuwiki/data/pages/man/eaccess.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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