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.Nm unlinkat 42.Nd remove directory entry 43.Sh SYNOPSIS 44.Fd #include <unistd.h> 45.Ft int 46.Fo unlink 47.Fa "const char *path" 48.Fc 49.Ft int 50.Fn unlinkat "int fd" "const char *path" "int flag" 51.Sh DESCRIPTION 52The 53.Fn unlink 54function 55removes the link named by 56.Fa path 57from its directory and decrements the link count of the 58file which was referenced by the link. 59If that decrement reduces the link count of the file 60to zero, 61and no process has the file open, then 62all resources associated with the file are reclaimed. 63If one or more process have the file open when the last link is removed, 64the link is removed, but the removal of the file is delayed until 65all references to it have been closed. 66.Pp 67The 68.Fn unlinkat 69system call is equivalent to 70.Fn unlink 71or 72.Fn rmdir 73except in the case where 74.Fa path 75specifies a relative path. 76In this case the directory entry to be removed is determined 77relative to the directory associated with the file descriptor 78.Fa fd 79instead of the current working directory. 80.Pp 81The values for 82.Fa flag 83are constructed by a bitwise-inclusive OR of flags from the following list, 84defined in 85.In fcntl.h : 86.Bl -tag -width indent 87.It Dv AT_REMOVEDIR 88Remove the directory entry specified by 89.Fa fd 90and 91.Fa path 92as a directory, not a normal file. 93.El 94.Pp 95If 96.Fn unlinkat 97is passed the special value 98.Dv AT_FDCWD 99in the 100.Fa fd 101parameter, the current working directory is used and the behavior is 102identical to a call to 103.Fa unlink 104or 105.Fa rmdir 106respectively, depending on whether or not the 107.Dv AT_REMOVEDIR 108bit is set in flag. 109.Sh RETURN VALUES 110Upon successful completion, a value of 0 is returned. 111Otherwise, a value of -1 is returned and 112.Va errno 113is set to indicate the error. 114.Sh ERRORS 115The 116.Fn unlink 117system call will fail if: 118.Bl -tag -width Er 119.\" =========== 120.It Bq Er EACCES 121Search permission is denied for a component of the path prefix. 122.\" =========== 123.It Bq Er EACCES 124Write permission is denied on the directory containing the link 125to be removed. 126.\" =========== 127.It Bq Er EBUSY 128The entry to be unlinked is the mount point for a 129mounted file system. 130.\" =========== 131.It Bq Er EBUSY 132The file named by the 133.Fa path 134argument cannot be unlinked 135because it is being used by the system or by another process. 136.\" =========== 137.It Bq Er EFAULT 138.Fa Path 139points outside the process's allocated address space. 140.\" =========== 141.It Bq Er EIO 142An I/O error occurs while deleting the directory entry 143or deallocating the inode. 144.\" =========== 145.It Bq Er ELOOP 146Too many symbolic links are encountered in translating the pathname. 147This is taken to be indicative of a looping symbolic link. 148.\" =========== 149.It Bq Er ENAMETOOLONG 150A component of a pathname exceeds 151.Dv {NAME_MAX} 152characters, or an entire path name exceeds 153.Dv {PATH_MAX} 154characters (possibly as a result of expanding a symlink). 155.\" =========== 156.It Bq Er ENOENT 157The named file does not exist. 158.\" =========== 159.It Bq Er ENOTDIR 160A component of the path prefix is not a directory. 161.\" =========== 162.It Bq Er EPERM 163The named file is a directory and the effective user ID 164of the process is not the super-user. 165.\" =========== 166.It Bq Er EPERM 167The directory containing the file is marked sticky, 168and neither the containing directory nor the file to be removed 169are owned by the effective user ID. 170.\" =========== 171.It Bq Er EROFS 172The named file resides on a read-only file system. 173.El 174.Pp 175In addition to the errors returned by the 176.Fn unlink , 177the 178.Fn unlinkat 179may fail if: 180.Bl -tag -width Er 181.It Bq Er EBADF 182The 183.Fa path 184argument does not specify an absolute path and the 185.Fa fd 186argument is neither 187.Dv AT_FDCWD 188nor a valid file descriptor open for searching. 189.It Bq Er ENOTEMPTY 190The 191.Fa flag 192parameter has the 193.Dv AT_REMOVEDIR 194bit set and the 195.Fa path 196argument names a directory that is not an empty directory, 197or there are hard links to the directory other than dot or 198a single entry in dot-dot. 199.It Bq Er ENOTDIR 200The 201.Fa flag 202parameter has the 203.Dv AT_REMOVEDIR 204bit set and 205.Fa path 206does not name a directory. 207.It Bq Er EINVAL 208The value of the 209.Fa flag 210argument is not valid. 211.It Bq Er ENOTDIR 212The 213.Fa path 214argument is not an absolute path and 215.Fa fd 216is neither 217.Dv AT_FDCWD 218nor a file descriptor associated with a directory. 219.El 220.Sh SEE ALSO 221.Xr close 2 , 222.Xr link 2 , 223.Xr rmdir 2 , 224.Xr symlink 7 225.Sh STANDARDS 226The 227.Fn unlinkat 228system call is expected to conform to POSIX.1-2008 . 229.Sh HISTORY 230An 231.Fn unlink 232function call appeared in 233.At v6 . 234The 235.Fn unlinkat 236system call appeared in OS X 10.10 237