[apple/xnu.git] / bsd / man / man2 / link.2

.\"	$NetBSD: link.2,v 1.7 1995/02/27 12:34:01 cgd Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)link.2	8.3 (Berkeley) 1/12/94
.\"
.Dd January 12, 1994
.Dt LINK 2
.Os BSD 4
.Sh NAME
.Nm link
.Nd make a hard file link
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn link "const char *name1" "const char *name2"
.Sh DESCRIPTION
The
.Fn link
function call
atomically creates the specified directory entry (hard link)
.Fa name2
with the attributes of the underlying object pointed at by
.Fa name1
If the link is successful: the link count of the underlying object
is incremented;
.Fa name1
and
.Fa name2
share equal access and rights
to the
underlying object.
.Pp
If
.Fa name1
is removed, the file
.Fa name2
is not deleted and the link count of the
underlying object is
decremented.
.Pp
.Fa Name1
must exist for the hard link to
succeed and
both
.Fa name1
and
.Fa name2
must be in the same file system.
As mandated by POSIX.1
.Fa name1
may not be a directory.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.  Otherwise,
a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn Link
will fail and no link will be created if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of either path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 
.Dv {NAME_MAX}
characters, or an entire path name exceeded 
.Dv {PATH_MAX}
characters.
.It Bq Er ENOENT
A component of either path prefix does not exist.
.It Bq Er EACCES
A component of either path prefix denies search permission.
.It Bq Er EACCES
The requested link requires writing in a directory with a mode
that denies write permission.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating one of the pathnames.
.It Bq Er ENOENT
The file named by
.Fa name1
does not exist.
.It Bq Er EEXIST
The link named by
.Fa name2
does exist.
.It Bq Er EPERM
The file named by
.Fa name1
is a directory.
.It Bq Er EXDEV
The link named by
.Fa name2
and the file named by
.Fa name1
are on different file systems.
.It Bq Er ENOSPC
The directory in which the entry for the new link is being placed
cannot be extended because there is no space left on the file
system containing the directory.
.ne 3v
.It Bq Er EDQUOT
The directory in which the entry for the new link
is being placed cannot be extended because the
user's quota of disk blocks on the file system
containing the directory has been exhausted.
.It Bq Er EIO
An I/O error occurred while reading from or writing to 
the file system to make the directory entry.
.It Bq Er EROFS
The requested link requires writing in a directory on a read-only file
system.
.It Bq Er EFAULT
One of the pathnames specified
is outside the process's allocated address space.
.El
.Sh SEE ALSO
.Xr symlink 2 ,
.Xr unlink 2
.Sh STANDARDS
The
.Fn link
function is expected to conform to 
.St -p1003.1-88 .
Commit	Line	Data
9bccf70c A	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	.Fn link "const char name1" "const char name2"
	46	.Sh DESCRIPTION
	47	The
	48	.Fn link
	49	function call
	50	atomically creates the specified directory entry (hard link)
	51	.Fa name2
	52	with the attributes of the underlying object pointed at by
	53	.Fa name1
	54	If the link is successful: the link count of the underlying object
	55	is incremented;
	56	.Fa name1
	57	and
	58	.Fa name2
	59	share equal access and rights
	60	to the
	61	underlying object.
	62	.Pp
	63	If
	64	.Fa name1
65	is removed, the file
66	.Fa name2
67	is not deleted and the link count of the
68	underlying object is
69	decremented.
70	.Pp
71	.Fa Name1
72	must exist for the hard link to
73	succeed and
74	both
75	.Fa name1
76	and
77	.Fa name2
78	must be in the same file system.
79	As mandated by POSIX.1
80	.Fa name1
81	may not be a directory.
82	.Sh RETURN VALUES
83	Upon successful completion, a value of 0 is returned. Otherwise,
84	a value of -1 is returned and
85	.Va errno
86	is set to indicate the error.
87	.Sh ERRORS
88	.Fn Link
89	will fail and no link will be created if:
90	.Bl -tag -width Er
91	.It Bq Er ENOTDIR
92	A component of either path prefix is not a directory.
93	.It Bq Er ENAMETOOLONG
94	A component of a pathname exceeded
95	.Dv {NAME_MAX}
96	characters, or an entire path name exceeded
97	.Dv {PATH_MAX}
98	characters.
99	.It Bq Er ENOENT
100	A component of either path prefix does not exist.
101	.It Bq Er EACCES
102	A component of either path prefix denies search permission.
103	.It Bq Er EACCES
104	The requested link requires writing in a directory with a mode
105	that denies write permission.
106	.It Bq Er ELOOP
107	Too many symbolic links were encountered in translating one of the pathnames.
108	.It Bq Er ENOENT
109	The file named by
110	.Fa name1
111	does not exist.
112	.It Bq Er EEXIST
113	The link named by
114	.Fa name2
115	does exist.
116	.It Bq Er EPERM
117	The file named by
118	.Fa name1
119	is a directory.
120	.It Bq Er EXDEV
121	The link named by
122	.Fa name2
123	and the file named by
124	.Fa name1
125	are on different file systems.
126	.It Bq Er ENOSPC
127	The directory in which the entry for the new link is being placed
128	cannot be extended because there is no space left on the file
129	system containing the directory.
130	.ne 3v
131	.It Bq Er EDQUOT
132	The directory in which the entry for the new link
133	is being placed cannot be extended because the
134	user's quota of disk blocks on the file system
135	containing the directory has been exhausted.
136	.It Bq Er EIO
137	An I/O error occurred while reading from or writing to
138	the file system to make the directory entry.
139	.It Bq Er EROFS
140	The requested link requires writing in a directory on a read-only file
141	system.
142	.It Bq Er EFAULT
143	One of the pathnames specified
144	is outside the process's allocated address space.
145	.El
146	.Sh SEE ALSO
147	.Xr symlink 2 ,
148	.Xr unlink 2
149	.Sh STANDARDS
150	The
151	.Fn link
152	function is expected to conform to
153	.St -p1003.1-88 .