1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)access.2 6.7 (Berkeley) 3/10/91 33.\" $Id: access.2,v 1.6 1994/04/22 00:13:22 jtc Exp $ 34.\" 35.Dd March 10, 1991 36.Dt ACCESS 2 37.Os BSD 4 38.Sh NAME 39.Nm access 40.Nd check access permissions of a file or pathname 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft int 44.Fn access "const char *path" "int mode" 45.Sh DESCRIPTION 46The 47.Fn access 48function checks the accessibility of the 49file named by 50.Fa path 51for the access permissions indicated by 52.Fa mode . 53The value of 54.Fa mode 55is the bitwise inclusive OR of the access permissions to be 56checked 57.Pf ( Dv R_OK 58for read permission, 59.Dv W_OK 60for write permission and 61.Dv X_OK 62for execute/search permission) or the existence test, 63.Dv F_OK . 64All components of the pathname 65.Fa path 66are checked for access permissions (including 67.Dv F_OK ) . 68.Pp 69The real user ID is used in place of the effective user ID 70and the real group access list 71(including the real group ID) are 72used in place of the effective ID for verifying permission. 73.Pp 74Even if a process has appropriate privileges and indicates success for 75.Dv X_OK , 76the file may not actually have execute permission bits set. 77Likewise for 78.Dv R_OK 79and 80.Dv W_OK . 81.Sh RETURN VALUES 82If 83.Fa path 84cannot be found or if any of the desired access modes would 85not be granted, then a -1 value is returned; otherwise 86a 0 value is returned. 87.Sh ERRORS 88Access to the file is denied if: 89.Bl -tag -width Er 90.It Bq Er ENOTDIR 91A component of the path prefix is not a directory. 92.It Bq Er ENAMETOOLONG 93A component of a pathname exceeded 94.Dv {NAME_MAX} 95characters, or an entire path name exceeded 96.Dv {PATH_MAX} 97characters. 98.It Bq Er ENOENT 99The named file does not exist. 100.It Bq Er ELOOP 101Too many symbolic links were encountered in translating the pathname. 102.It Bq Er EROFS 103Write access is requested for a file on a read-only file system. 104.It Bq Er ETXTBSY 105Write access is requested for a pure procedure (shared text) 106file presently being executed. 107.It Bq Er EACCES 108Permission bits of the file mode do not permit the requested 109access, or search permission is denied on a component of the 110path prefix. The owner of a file has permission checked with 111respect to the ``owner'' read, write, and execute mode bits, 112members of the file's group other than the owner have permission 113checked with respect to the ``group'' mode bits, and all 114others have permissions checked with respect to the ``other'' 115mode bits. 116.It Bq Er EFAULT 117.Fa Path 118points outside the process's allocated address space. 119.It Bq Er EIO 120An I/O error occurred while reading from or writing to the file system. 121.El 122.Sh SEE ALSO 123.Xr chmod 2 , 124.Xr stat 2 125.Sh STANDARDS 126The 127.Fn access 128function conforms to 129.St -p1003.1-88 . 130.Sh CAVEAT 131.Fn Access 132is a potential security hole and 133should never be used. 134