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.\" @(#)access.2 6.7 (Berkeley) 3/10/91
.Nd check access permissions of a file or pathname
.Fn access "const char *path" "int mode"
function checks the accessibility of the
for the access permissions indicated by
is the bitwise inclusive OR of the access permissions to be
for execute/search permission) or the existence test,
All components of the pathname
are checked for access permissions (including
The real user ID is used in place of the effective user ID
and the real group access list
(including the real group ID) are
used in place of the effective ID for verifying permission.
Even if a process has appropriate privileges and indicates success for
the file may not actually have execute permission bits set.
cannot be found or if any of the desired access modes would
not be granted, then a -1 value is returned; otherwise
Access to the file is denied if:
A component of the path prefix is not a directory.
The pathname contains a character with the high-order bit set.
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
The named file does not exist.
Search permission is denied for a component of the path prefix.
Too many symbolic links were encountered in translating the pathname.
Write access is requested for a file on a read-only file system.
Write access is requested for a pure procedure (shared text)
file presently being executed.
Permission bits of the file mode do not permit the requested
access, or search permission is denied on a component of the
path prefix. The owner of a file has permission checked with
respect to the ``owner'' read, write, and execute mode bits,
members of the file's group other than the owner have permission
checked with respect to the ``group'' mode bits, and all
others have permissions checked with respect to the ``other''
points outside the process's allocated address space.
An I/O error occurred while reading from or writing to the file system.
conforms to IEEE Std 1003.1-1988
is a potential security hole and