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

.\"	$NetBSD: symlink.2,v 1.7 1995/02/27 12:38:34 cgd Exp $
.\"
.\" Copyright (c) 1983, 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.
.\"
.\"     @(#)symlink.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SYMLINK 2
.Os BSD 4.2
.Sh NAME
.Nm symlink ,
.Nm symlinkat
.Nd make symbolic link to a file
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fo symlink
.Fa "const char *path1"
.Fa "const char *path2"
.Fc
.Ft int
.Fn symlinkat "const char *name1" "int fd" "const char *name2"
.Sh DESCRIPTION
A symbolic link
.Fa path2
is created to
.Fa path1
.Pf ( Fa path2
is the name of the
file created,
.Fa path1
is the string
used in creating the symbolic link).
Either name may be an arbitrary path name; the files need not
be on the same file system.
.Pp
The
.Fn symlinkat
system call is equivalent to
.Fn symlink
except in the case where
.Fa name2
specifies a relative path.
In this case the symbolic link is created relative to the directory
associated with the file descriptor
.Fa fd
instead of the current working directory.
If
.Fn symlinkat
is passed the special value
.Dv AT_FDCWD
in the
.Fa fd
parameter, the current working directory is used and the behavior is
identical to a call to
.Fn symlink .
.Sh RETURN VALUES
Upon successful completion, a zero value is returned.
If an error occurs, the error code is stored in
.Va errno
and a -1 value is returned.
.Sh ERRORS
The symbolic link succeeds unless:
.Bl -tag -width Er
.\" ===========
.It Bq Er EACCES
Write permission is denied in the directory
where the symbolic link is being created.
.\" ===========
.It Bq Er EACCES
A component of the
.Fa path2
path prefix denies search permission.
.\" ===========
.It Bq Er EDQUOT
The directory in which the entry for the new symbolic 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 EDQUOT
The new symbolic link cannot be created because the user's
quota of disk blocks on the file system that will
contain the symbolic link has been exhausted.
.\" ===========
.It Bq Er EDQUOT
The user's quota of inodes on the file system on
which the symbolic link is being created has been exhausted.
.\" ===========
.It Bq Er EEXIST
.Fa Path2
already exists.
.\" ===========
.It Bq Er EFAULT
.Fa Path1
or
.Fa path2
points outside the process's allocated address space.
.\" ===========
.It Bq Er EIO
An I/O error occurs while making the directory entry
or allocating the inode.
.\" ===========
.It Bq Er EIO
An I/O error occurs while making the directory entry for
.Fa path2 ,
or allocating the inode for
.Fa path2 ,
or writing out the link contents of
.Fa path2 .
.\" ===========
.It Bq Er ELOOP
Too many symbolic links are encountered in translating the pathname.
This is taken to be indicative of a looping symbolic link.
.\" ===========
.It Bq Er ENAMETOOLONG
A component of a pathname exceeds 
.Dv {NAME_MAX}
characters, or an entire path name exceeds
.Dv {PATH_MAX}
characters.
.\" ===========
.It Bq Er ENOENT
A component of
.Fa path2
does not name an existing file or
.Fa path2
is an empty string.
.\" ===========
.It Bq Er ENOSPC
The directory in which the entry for the new symbolic link is being placed
cannot be extended because there is no space left on the file
system containing the directory.
.\" ===========
.It Bq Er ENOSPC
The new symbolic link cannot be created because there
there is no space left on the file
system that will contain the symbolic link.
.\" ===========
.It Bq Er ENOSPC
There are no free inodes on the file system on which the
symbolic link is being created.
.\" ===========
.It Bq Er ENOTDIR
A component of the
.Fa path2
prefix is not a directory.
.\" ===========
.It Bq Er EROFS
The file
.Fa path2
would reside on a read-only file system.
.El
.Pp
In addition to the errors returned by the
.Fn symlink ,
the
.Fn symlinkat
may fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa name2
argument does not specify an absolute path and the
.Fa fd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor open for searching.
.It Bq Er ENOTDIR
The
.Fa name2
argument is not an absolute path and
.Fa fd
is neither
.Dv AT_FDCWD
nor a file descriptor associated with a directory.
.El
.Sh SEE ALSO
.Xr ln 1 ,
.Xr link 2 ,
.Xr unlink 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn symlinkat
system call is expected to conform to POSIX.1-2008 .
.Sh HISTORY
The
.Fn symlink
function call appeared in
.Bx 4.2 .
The
.Fn symlinkat
system call appeared in OS X 10.10
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: symlink.2,v 1.7 1995/02/27 12:38:34 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1983, 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	.\" @(#)symlink.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt SYMLINK 2
	38	.Os BSD 4.2
	39	.Sh NAME
fe8ab488 A	40	.Nm symlink ,
fe8ab488 A	41	.Nm symlinkat
9bccf70c A	42	.Nd make symbolic link to a file
	43	.Sh SYNOPSIS
	44	.Fd #include <unistd.h>
	45	.Ft int
2d21ac55 A	46	.Fo symlink
	47	.Fa "const char *path1"
	48	.Fa "const char *path2"
	49	.Fc
fe8ab488 A	50	.Ft int
fe8ab488 A	51	.Fn symlinkat "const char name1" "int fd" "const char name2"
9bccf70c A	52	.Sh DESCRIPTION
9bccf70c A	53	A symbolic link
2d21ac55	54	.Fa path2
9bccf70c	55	is created to
2d21ac55 A	56	.Fa path1
2d21ac55 A	57	.Pf ( Fa path2
9bccf70c A	58	is the name of the
9bccf70c A	59	file created,
2d21ac55	60	.Fa path1
9bccf70c A	61	is the string
	62	used in creating the symbolic link).
	63	Either name may be an arbitrary path name; the files need not
	64	be on the same file system.
fe8ab488 A	65	.Pp
	66	The
	67	.Fn symlinkat
	68	system call is equivalent to
	69	.Fn symlink
	70	except in the case where
	71	.Fa name2
	72	specifies a relative path.
	73	In this case the symbolic link is created relative to the directory
	74	associated with the file descriptor
	75	.Fa fd
	76	instead of the current working directory.
	77	If
	78	.Fn symlinkat
	79	is passed the special value
	80	.Dv AT_FDCWD
	81	in the
	82	.Fa fd
	83	parameter, the current working directory is used and the behavior is
	84	identical to a call to
	85	.Fn symlink .
9bccf70c A	86	.Sh RETURN VALUES
	87	Upon successful completion, a zero value is returned.
	88	If an error occurs, the error code is stored in
	89	.Va errno
	90	and a -1 value is returned.
	91	.Sh ERRORS
	92	The symbolic link succeeds unless:
	93	.Bl -tag -width Er
2d21ac55 A	94	.\" ===========
	95	.It Bq Er EACCES
	96	Write permission is denied in the directory
	97	where the symbolic link is being created.
	98	.\" ===========
9bccf70c A	99	.It Bq Er EACCES
9bccf70c A	100	A component of the
2d21ac55	101	.Fa path2
9bccf70c	102	path prefix denies search permission.
2d21ac55 A	103	.\" ===========
	104	.It Bq Er EDQUOT
	105	The directory in which the entry for the new symbolic 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 EDQUOT
	111	The new symbolic link cannot be created because the user's
	112	quota of disk blocks on the file system that will
	113	contain the symbolic link has been exhausted.
	114	.\" ===========
	115	.It Bq Er EDQUOT
	116	The user's quota of inodes on the file system on
	117	which the symbolic link is being created has been exhausted.
	118	.\" ===========
9bccf70c	119	.It Bq Er EEXIST
2d21ac55	120	.Fa Path2
9bccf70c	121	already exists.
2d21ac55 A	122	.\" ===========
	123	.It Bq Er EFAULT
	124	.Fa Path1
	125	or
	126	.Fa path2
	127	points outside the process's allocated address space.
	128	.\" ===========
	129	.It Bq Er EIO
	130	An I/O error occurs while making the directory entry
	131	or allocating the inode.
	132	.\" ===========
9bccf70c	133	.It Bq Er EIO
2d21ac55 A	134	An I/O error occurs while making the directory entry for
2d21ac55 A	135	.Fa path2 ,
9bccf70c	136	or allocating the inode for
2d21ac55	137	.Fa path2 ,
9bccf70c	138	or writing out the link contents of
2d21ac55 A	139	.Fa path2 .
	140	.\" ===========
	141	.It Bq Er ELOOP
	142	Too many symbolic links are encountered in translating the pathname.
	143	This is taken to be indicative of a looping symbolic link.
	144	.\" ===========
	145	.It Bq Er ENAMETOOLONG
	146	A component of a pathname exceeds
	147	.Dv {NAME_MAX}
	148	characters, or an entire path name exceeds
	149	.Dv {PATH_MAX}
	150	characters.
	151	.\" ===========
	152	.It Bq Er ENOENT
	153	A component of
	154	.Fa path2
	155	does not name an existing file or
	156	.Fa path2
	157	is an empty string.
	158	.\" ===========
9bccf70c A	159	.It Bq Er ENOSPC
	160	The directory in which the entry for the new symbolic link is being placed
	161	cannot be extended because there is no space left on the file
	162	system containing the directory.
2d21ac55	163	.\" ===========
9bccf70c A	164	.It Bq Er ENOSPC
	165	The new symbolic link cannot be created because there
	166	there is no space left on the file
	167	system that will contain the symbolic link.
2d21ac55	168	.\" ===========
9bccf70c A	169	.It Bq Er ENOSPC
	170	There are no free inodes on the file system on which the
	171	symbolic link is being created.
2d21ac55 A	172	.\" ===========
	173	.It Bq Er ENOTDIR
	174	A component of the
	175	.Fa path2
	176	prefix is not a directory.
	177	.\" ===========
	178	.It Bq Er EROFS
	179	The file
	180	.Fa path2
	181	would reside on a read-only file system.
9bccf70c	182	.El
fe8ab488 A	183	.Pp
	184	In addition to the errors returned by the
	185	.Fn symlink ,
	186	the
	187	.Fn symlinkat
	188	may fail if:
	189	.Bl -tag -width Er
	190	.It Bq Er EBADF
	191	The
	192	.Fa name2
	193	argument does not specify an absolute path and the
	194	.Fa fd
	195	argument is neither
	196	.Dv AT_FDCWD
	197	nor a valid file descriptor open for searching.
	198	.It Bq Er ENOTDIR
	199	The
	200	.Fa name2
	201	argument is not an absolute path and
	202	.Fa fd
	203	is neither
	204	.Dv AT_FDCWD
	205	nor a file descriptor associated with a directory.
	206	.El
9bccf70c A	207	.Sh SEE ALSO
	208	.Xr ln 1 ,
	209	.Xr link 2 ,
2d21ac55 A	210	.Xr unlink 2 ,
2d21ac55 A	211	.Xr symlink 7
fe8ab488 A	212	.Sh STANDARDS
	213	The
	214	.Fn symlinkat
	215	system call is expected to conform to POSIX.1-2008 .
9bccf70c A	216	.Sh HISTORY
	217	The
	218	.Fn symlink
	219	function call appeared in
	220	.Bx 4.2 .
fe8ab488 A	221	The
	222	.Fn symlinkat
	223	system call appeared in OS X 10.10