access
Hurricane Electric Internet Services
NAME
access - check user's permissions for a file
SYNOPSIS
#include <unistd.h>
int access(const char *pathname, int mode);
DESCRIPTION
access checks whether the process would be allowed to
read, write or test for existence of the file (or other
file system object) whose name is pathname.
mode is a mask consisting of one or more of R_OK, W_OK,
X_OK and F_OK.
R_OK, W_OK and X_OK request testing for reading, writing
and executing the file, respectively. F_OK requests
checking whether merely testing for the existence of the
file would be allowed (this depends on the permissions of
the directories in the path to the file, as given in path-
name.)
The check is done with the process's real uid and gid,
rather than with the effective ids as is done when actu-
ally attempting an operation. This is to allow set-UID
programs to easily determine the invoking user's author-
ity.
Only access bits are checked, not the file type or con-
tents. Therefore, if a directory is found to be
"writable," it probably means that files can be created in
the directory, and not that the directory can be written
as a file. Similarly, a DOS file may be found to be "exe-
cutable," but the execve(2) call will still fail.
RETURN VALUE
On success, zero is returned. On error, -1 is returned,
and errno is set appropriately.
ERRORS
EACCES The requested access would be denied, either to
the file itself or one of the directories in path-
name.
EFAULT pathname points outside your accessible address
space.
EINVAL mode was incorrectly specified.
ENAMETOOLONG
pathname is too long.
ENOENT A directory component in pathname would have been
accessible but does not exist or was a dangling
symbolic link.
ENOTDIR A component used as a directory in pathname is
not, in fact, a directory.
ENOMEM Insufficient kernel memory was available.
ELOOP pathname contains a reference to a circular sym-
bolic link, i.e., a symbolic link containing a
reference to itself.
CONFORMING TO
SVID, AT&T, POSIX, X/OPEN, BSD 4.3
SEE ALSO
stat(2), open(2), chmod(2), chown(2), setuid(2), set-
gid(2).
Hurricane Electric Internet Services
Copyright (C) 1998
Hurricane Electric.
All Rights Reserved.