1.\" $OpenBSD: unlink.2,v 1.23 2014/02/13 07:30:39 guenther Exp $ 2.\" $NetBSD: unlink.2,v 1.7 1995/02/27 12:39:13 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)unlink.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: February 13 2014 $ 34.Dt UNLINK 2 35.Os 36.Sh NAME 37.Nm unlink , 38.Nm unlinkat 39.Nd remove directory entry 40.Sh SYNOPSIS 41.Fd #include <unistd.h> 42.Ft int 43.Fn unlink "const char *path" 44.Fd #include <fcntl.h> 45.Fd #include <unistd.h> 46.Ft int 47.Fn unlinkat "int fd" "const char *path" "int flag" 48.Sh DESCRIPTION 49The 50.Fn unlink 51function removes the link named by 52.Fa path 53from its directory and decrements the link count of the 54file which was referenced by the link. 55If that decrement reduces the link count of the file 56to zero, 57and no process has the file open, then 58all resources associated with the file are reclaimed. 59If one or more processes have the file open when the last link is removed, 60the link is removed, but the removal of the file is delayed until 61all references to it have been closed. 62.Pp 63The 64.Fn unlinkat 65function is equivalent to either the 66.Fn unlink 67or 68.Xr rmdir 2 69function depending on the value of 70.Fa flag 71(see below), except that where 72.Fa path 73specifies a relative path, 74the directory entry to be removed is determined relative to 75the directory associated with file descriptor 76.Fa fd 77instead of the current working directory. 78.Pp 79If 80.Fn unlinkat 81is passed the special value 82.Dv AT_FDCWD 83(defined in 84.In fcntl.h ) 85in the 86.Fa fd 87parameter, the current working directory is used 88and the behavior is identical to a call to 89.Fn unlink 90or 91.Xr rmdir 2 , 92depending on whether or not the 93.Dv AT_REMOVEDIR 94bit is set in 95.Fa flag . 96.Pp 97The 98.Fa flag 99argument is the bitwise OR of zero or more of the following values: 100.Pp 101.Bl -tag -width AT_REMOVEDIR -offset indent -compact 102.It Dv AT_REMOVEDIR 103Remove the directory entry specified by 104.Fa path 105as a directory, not a normal file. 106.El 107.Sh RETURN VALUES 108Upon successful completion, a value of 0 is returned. 109Otherwise, a value of \-1 is returned and 110.Va errno 111is set to indicate the error. 112.Sh ERRORS 113The 114.Fn unlink 115and 116.Fn unlinkat 117functions will fail if: 118.Bl -tag -width Er 119.It Bq Er ENOTDIR 120A component of the path prefix is not a directory. 121.It Bq Er ENAMETOOLONG 122A component of a pathname exceeded 123.Dv {NAME_MAX} 124characters, or an entire path name exceeded 125.Dv {PATH_MAX} 126characters. 127.It Bq Er ENOENT 128The named file does not exist. 129.It Bq Er EACCES 130Search permission is denied for a component of the path prefix. 131.It Bq Er EACCES 132Write permission is denied on the directory containing the link 133to be removed. 134.It Bq Er ELOOP 135Too many symbolic links were encountered in translating the pathname. 136.It Bq Er EPERM 137The named file is a directory and the effective user ID 138of the process is not the superuser, or the file system 139containing the file does not permit the use of 140.Fn unlink 141on a directory. 142.It Bq Er EPERM 143The directory containing the file is marked sticky, 144and neither the containing directory nor the file to be removed 145are owned by the effective user ID. 146.It Bq Er EPERM 147The named file has its immutable or append-only flag set (see 148.Xr chflags 2 ) . 149.It Bq Er EBUSY 150The entry to be unlinked is the mount point for a 151mounted file system. 152.It Bq Er EIO 153An I/O error occurred while deleting the directory entry 154or deallocating the inode. 155.It Bq Er EROFS 156The named file resides on a read-only file system. 157.It Bq Er EFAULT 158.Fa path 159points outside the process's allocated address space. 160.El 161.Pp 162Additionally, 163.Fn unlinkat 164will fail if: 165.Bl -tag -width Er 166.It Bq Er ENOTDIR 167The 168.Dv AT_REMOVEDIR 169flag bit is set and 170.Fa path 171does not name a directory. 172.It Bq Er ENOTEMPTY 173The 174.Dv AT_REMOVEDIR 175flag bit is set and the named directory contains files other than 176.Ql \&. 177and 178.Ql \&.. 179in it. 180.It Bq Er EINVAL 181The value of the 182.Fa flag 183argument was neither zero nor 184.Dv AT_REMOVEDIR . 185.It Bq Er EBADF 186The 187.Fa path 188argument specifies a relative path and the 189.Fa fd 190argument is neither 191.Dv AT_FDCWD 192nor a valid file descriptor. 193.It Bq Er ENOTDIR 194The 195.Fa path 196argument specifies a relative path and the 197.Fa fd 198argument is a valid file descriptor but it does not reference a directory. 199.It Bq Er EACCES 200The 201.Fa path 202argument specifies a relative path but search permission is denied 203for the directory which the 204.Fa fd 205file descriptor references. 206.El 207.Sh SEE ALSO 208.Xr rm 1 , 209.Xr close 2 , 210.Xr link 2 , 211.Xr rmdir 2 , 212.Xr symlink 7 213.Sh STANDARDS 214The 215.Fn unlink 216and 217.Fn unlinkat 218functions conform to 219.St -p1003.1-2008 . 220.Sh HISTORY 221The 222.Fn unlink 223system call first appeared in 224.At v1 . 225The 226.Fn unlinkat 227function appeared in 228.Ox 5.0 . 229