Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
ACCESS(2)                 FreeBSD System Calls Manual                ACCESS(2)

NAME
     access, eaccess - check accessibility of a file

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     access(const char *path, int mode);

     int
     eaccess(const char *path, int mode);

DESCRIPTION
     The access() and eaccess() functions check the accessibility of the file
     named by the path argument for the access permissions indicated by the
     mode argument.  The value of mode is either the bitwise-inclusive OR of
     the access permissions to be checked (R_OK for read permission, W_OK for
     write permission, and X_OK for execute/search permission), or the
     existence test (F_OK).

     For additional information, see the File Access Permission section of
     intro(2).

     The eaccess() call uses the effective user ID and the group access list
     to authorize the request; the access() call uses the real user ID in
     place of the effective user ID, the real group ID in place of the
     effective group ID, and the rest of the group access list.

     Even if a process's real or effective user has appropriate privileges and
     indicates success for X_OK, the file may not actually have execute
     permission bits set.  Likewise for R_OK and W_OK.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     Access to the file is denied if:

     [ENOTDIR]          A component of the path prefix is not a directory.

     [ENAMETOOLONG]     A component of a pathname exceeded 255 characters, or
                        an entire path name exceeded 1023 characters.

     [ENOENT]           The named file does not exist.

     [ELOOP]            Too many symbolic links were encountered in
                        translating the pathname.

     [EROFS]            Write access is requested for a file on a read-only
                        file system.

     [ETXTBSY]          Write access is requested for a pure procedure (shared
                        text) file presently being executed.

     [EACCES]           Permission bits of the file mode do not permit the
                        requested access, or search permission is denied on a
                        component of the path prefix.

     [EFAULT]           path points outside the process's allocated address
                        space.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

SECURITY CONSIDERATIONS
     The access() call is a potential security hole due to race conditions and
     should never be used.  Set-user-ID and set-group-ID applications should
     restore the effective user or group ID, and perform actions directly
     rather than use access() to simulate access checks for the real user or
     group ID.  The eaccess() call likewise may be subject to races if used
     inappropriately.

SEE ALSO
     chmod(2), intro(2), stat(2)

STANDARDS
     The access() function call is expected to conform to IEEE Std 1003.1-1990
     (``POSIX.1'').

HISTORY
     An access() function call appeared in Version 7 AT&T UNIX.

FreeBSD 11.0-PRERELEASE       September 21, 2001       FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SECURITY CONSIDERATIONS | SEE ALSO | STANDARDS | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=eaccess&sektion=2&manpath=FreeBSD+5.0-RELEASE>

home | help