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	1	.\" $NetBSD: link.2,v 1.7 1995/02/27 12:34:01 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1980, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)link.2 8.3 (Berkeley) 1/12/94
	35	.\"
	36	.Dd January 12, 1994
	37	.Dt LINK 2
	38	.Os BSD 4
	39	.Sh NAME
	40	.Nm link
	41	.Nd make a hard file link
	42	.Sh SYNOPSIS
	43	.Fd #include <unistd.h>
	44	.Ft int
	45	.Fo link
	46	.Fa "const char *path1"
	47	.Fa "const char *path2"
	48	.Fc
	49	.Sh DESCRIPTION
	50	The
	51	.Fn link
	52	function call
	53	atomically creates the specified directory entry (hard link)
	54	.Fa path2
	55	with the attributes of the underlying object pointed at by
	56	.Fa path1 .
	57	If the link is successful,
	58	the link count of the underlying object is incremented;
	59	.Fa path1
	60	and
	61	.Fa path2
	62	share equal access and rights
	63	to the
	64	underlying object.
	65	.Pp
	66	If
	67	.Fa path1
	68	is removed, the file
	69	.Fa path2
	70	is not deleted and the link count of the
	71	underlying object is
	72	decremented.
	73	.Pp
	74	In order for the system call to succeed,
	75	.Fa path1
	76	must exist and both
	77	.Fa path1
	78	and
	79	.Fa path2
	80	must be in the same file system.
	81	As mandated by POSIX.1,
	82	.Fa path1
	83	may not be a directory.
	84	.Sh RETURN VALUES
	85	Upon successful completion, a value of 0 is returned. Otherwise,
	86	a value of -1 is returned and
	87	.Va errno
	88	is set to indicate the error.
	89	.Sh ERRORS
	90	.Fn Link
	91	will fail and no link will be created if:
	92	.Bl -tag -width Er
	93	.\" ==========
	94	.It Bq Er EACCES
	95	A component of either path prefix denies search permission.
	96	.\" ==========
	97	.It Bq Er EACCES
	98	The requested link requires writing in a directory with a mode
	99	that denies write permission.
	100	.\" ==========
	101	.It Bq Er EACCES
	102	The current process cannot access the existing file.
	103	.\" ==========
	104	.It Bq Er EDQUOT
	105	The directory in which the entry for the new link
	106	is being placed cannot be extended because the
	107	user's quota of disk blocks on the file system
	108	containing the directory has been exhausted.
	109	.\" ==========
	110	.It Bq Er EEXIST
	111	The link named by
	112	.Fa path2
	113	already exists.
	114	.\" ==========
	115	.It Bq Er EFAULT
	116	One of the pathnames specified
	117	is outside the process's allocated address space.
	118	.\" ==========
	119	.It Bq Er EIO
	120	An I/O error occurs while reading from or writing to
	121	the file system to make the directory entry.
	122	.\" ==========
	123	.It Bq Er ELOOP
	124	Too many symbolic links are encountered in translating one of the pathnames.
	125	This is taken to be indicative of a looping symbolic link.
	126	.\" ==========
	127	.It Bq Er EMLINK
	128	The file already has {LINK_MAX} links.
	129	.\" ==========
	130	.It Bq Er ENAMETOOLONG
	131	A component of a pathname exceeds
	132	.Dv {NAME_MAX}
	133	characters, or an entire path name exceeded
	134	.Dv {PATH_MAX}
	135	characters.
	136	.\" ==========
	137	.It Bq Er ENOENT
	138	A component of either path prefix does not exist.
	139	.\" ==========
	140	.It Bq Er ENOENT
	141	The file named by
	142	.Fa path1
	143	does not exist.
	144	.\" ==========
	145	.It Bq Er ENOSPC
	146	The directory in which the entry for the new link is being placed
	147	cannot be extended because there is no space left on the file
	148	system containing the directory.
	149	.\" ==========
	150	.It Bq Er ENOTDIR
	151	A component of either path prefix is not a directory.
	152	.\" ==========
	153	.It Bq Er EPERM
	154	The file named by
	155	.Fa path1
	156	is a directory.
	157	.\" ==========
	158	.It Bq Er EROFS
	159	The requested link requires writing in a directory
	160	on a read-only file system.
	161	.\" ==========
	162	.It Bq Er EXDEV
	163	The link named by
	164	.Fa path2
	165	and the file named by
	166	.Fa path1
	167	are on different file systems.
	168	.El
	169	.Sh SEE ALSO
	170	.Xr symlink 2 ,
	171	.Xr unlink 2
	172	.Sh STANDARDS
	173	The
	174	.Fn link
	175	function is expected to conform to
	176	.St -p1003.1-88 .