access(2) BSD System Calls Manual access(2)
NAME
access -- check access permissions of a file or pathname
SYNOPSIS
#include <unistd.h>
int
access(const char *path, int amode);
DESCRIPTION
The access() function checks the accessibility of the file named by path
for the access permissions indicated by amode. The value of amode is 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. All components of the pathname
path are checked for access permissions (including F_OK).
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
X_OK, the file may not actually have execute permission bits set. Like-
wise for R_OK and W_OK.
RETURN VALUES
If path cannot be found or if any of the desired access modes would not
be granted, then a -1 value is returned and the global integer variable
errno is set to indicate the error. Otherwise, a 0 value is returned.
ERRORS
Access to the file is denied if:
[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.
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'' mode bits.
[EFAULT] Path points outside the process's allocated address
space.
[EINVAL] An invalid value was specified for amode.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[ELOOP] Too many symbolic links were encountered in translat-
ing the pathname.
[ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} charac-
ters, or an entire path name exceeded {PATH_MAX} char-
acters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
[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 that is presently being executed.
SEE ALSO
chmod(2), stat(2)
STANDARDS
The access() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
CAVEAT
Access() is a potential security hole and should never be used.
4th Berkeley Distribution April 1, 1994 4th Berkeley Distribution
Mac OS X 10.9.1 - Generated Sun Jan 5 15:57:03 CST 2014