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

.\"	$NetBSD: unlink.2,v 1.7 1995/02/27 12:39:13 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.
.\"
.\"     @(#)unlink.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt UNLINK 2
.Os BSD 4
.Sh NAME
.Nm unlink
.Nd remove directory entry
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fo unlink
.Fa "const char *path"
.Fc
.Sh DESCRIPTION
The
.Fn unlink
function
removes the link named by
.Fa path
from its directory and decrements the link count of the
file which was referenced by the link.
If that decrement reduces the link count of the file
to zero,
and no process has the file open, then
all resources associated with the file are reclaimed.
If one or more process have the file open when the last link is removed,
the link is removed, but the removal of the file is delayed until
all references to it have been closed.
.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
The
.Fn unlink
system call will fail if:
.Bl -tag -width Er
.\" ===========
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.\" ===========
.It Bq Er EACCES
Write permission is denied on the directory containing the link
to be removed.
.\" ===========
.It Bq Er EBUSY
The entry to be unlinked is the mount point for a
mounted file system.
.\" ===========
.It Bq Er EBUSY
The file named by the
.Fa path
argument cannot be unlinked
because it is being used by the system or by another process.
.\" ===========
.It Bq Er EFAULT
.Fa Path
points outside the process's allocated address space.
.\" ===========
.It Bq Er EIO
An I/O error occurs while deleting the directory entry
or deallocating the inode.
.\" ===========
.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 (possibly as a result of expanding a symlink).
.\" ===========
.It Bq Er ENOENT
The named file does not exist.
.\" ===========
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.\" ===========
.It Bq Er EPERM
The named file is a directory and the effective user ID
of the process is not the super-user.
.\" ===========
.It Bq Er EPERM
The directory containing the file is marked sticky,
and neither the containing directory nor the file to be removed
are owned by the effective user ID.
.\" ===========
.It Bq Er EROFS
The named file resides on a read-only file system.
.El
.Sh SEE ALSO
.Xr close 2 ,
.Xr link 2 ,
.Xr rmdir 2 ,
.Xr symlink 7
.Sh HISTORY
An
.Fn unlink
function call appeared in 
.At v6 .
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: unlink.2,v 1.7 1995/02/27 12:39:13 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	.\" @(#)unlink.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt UNLINK 2
	38	.Os BSD 4
	39	.Sh NAME
	40	.Nm unlink
	41	.Nd remove directory entry
	42	.Sh SYNOPSIS
	43	.Fd #include <unistd.h>
	44	.Ft int
2d21ac55 A	45	.Fo unlink
	46	.Fa "const char *path"
	47	.Fc
9bccf70c A	48	.Sh DESCRIPTION
	49	The
	50	.Fn unlink
	51	function
	52	removes the link named by
	53	.Fa path
	54	from its directory and decrements the link count of the
	55	file which was referenced by the link.
	56	If that decrement reduces the link count of the file
	57	to zero,
	58	and no process has the file open, then
	59	all resources associated with the file are reclaimed.
	60	If one or more process have the file open when the last link is removed,
	61	the link is removed, but the removal of the file is delayed until
	62	all references to it have been closed.
	63	.Sh RETURN VALUES
	64	Upon successful completion, a value of 0 is returned.
	65	Otherwise, a value of -1 is returned and
	66	.Va errno
	67	is set to indicate the error.
	68	.Sh ERRORS
	69	The
	70	.Fn unlink
2d21ac55	71	system call will fail if:
9bccf70c	72	.Bl -tag -width Er
2d21ac55	73	.\" ===========
9bccf70c A	74	.It Bq Er EACCES
9bccf70c A	75	Search permission is denied for a component of the path prefix.
2d21ac55	76	.\" ===========
9bccf70c A	77	.It Bq Er EACCES
	78	Write permission is denied on the directory containing the link
	79	to be removed.
2d21ac55 A	80	.\" ===========
	81	.It Bq Er EBUSY
	82	The entry to be unlinked is the mount point for a
	83	mounted file system.
	84	.\" ===========
	85	.It Bq Er EBUSY
	86	The file named by the
	87	.Fa path
	88	argument cannot be unlinked
	89	because it is being used by the system or by another process.
	90	.\" ===========
	91	.It Bq Er EFAULT
	92	.Fa Path
	93	points outside the process's allocated address space.
	94	.\" ===========
	95	.It Bq Er EIO
	96	An I/O error occurs while deleting the directory entry
	97	or deallocating the inode.
	98	.\" ===========
9bccf70c	99	.It Bq Er ELOOP
2d21ac55 A	100	Too many symbolic links are encountered in translating the pathname.
	101	This is taken to be indicative of a looping symbolic link.
	102	.\" ===========
	103	.It Bq Er ENAMETOOLONG
	104	A component of a pathname exceeds
	105	.Dv {NAME_MAX}
	106	characters, or an entire path name exceeds
	107	.Dv {PATH_MAX}
	108	characters (possibly as a result of expanding a symlink).
	109	.\" ===========
	110	.It Bq Er ENOENT
	111	The named file does not exist.
	112	.\" ===========
	113	.It Bq Er ENOTDIR
	114	A component of the path prefix is not a directory.
	115	.\" ===========
9bccf70c A	116	.It Bq Er EPERM
	117	The named file is a directory and the effective user ID
	118	of the process is not the super-user.
2d21ac55	119	.\" ===========
9bccf70c A	120	.It Bq Er EPERM
	121	The directory containing the file is marked sticky,
	122	and neither the containing directory nor the file to be removed
	123	are owned by the effective user ID.
2d21ac55	124	.\" ===========
9bccf70c A	125	.It Bq Er EROFS
9bccf70c A	126	The named file resides on a read-only file system.
9bccf70c A	127	.El
	128	.Sh SEE ALSO
	129	.Xr close 2 ,
	130	.Xr link 2 ,
2d21ac55	131	.Xr rmdir 2 ,
9bccf70c A	132	.Xr symlink 7
	133	.Sh HISTORY
	134	An
	135	.Fn unlink
	136	function call appeared in
	137	.At v6 .