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Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)unlink.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd June 6, 2019 32.Dt UNLINK 2 33.Os 34.Sh NAME 35.Nm unlink , 36.Nm unlinkat , 37.Nm funlinkat 38.Nd remove directory entry 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In unistd.h 43.Ft int 44.Fn unlink "const char *path" 45.Ft int 46.Fn unlinkat "int dfd" "const char *path" "int flag" 47.Ft int 48.Fn funlinkat "int dfd" "const char *path" "int fd" "int flag" 49.Sh DESCRIPTION 50The 51.Fn unlink 52system call 53removes the link named by 54.Fa path 55from its directory and decrements the link count of the 56file which was referenced by the link. 57If that decrement reduces the link count of the file 58to zero, 59and no process has the file open, then 60all resources associated with the file are reclaimed. 61If one or more process have the file open when the last link is removed, 62the link is removed, but the removal of the file is delayed until 63all references to it have been closed. 64The 65.Fa path 66argument 67may not be a directory. 68.Pp 69The 70.Fn unlinkat 71system call is equivalent to 72.Fn unlink 73or 74.Fn rmdir 75except in the case where 76.Fa path 77specifies a relative path. 78In this case the directory entry to be removed is determined 79relative to the directory associated with the file descriptor 80.Fa dfd 81instead of the current working directory. 82.Pp 83The values for 84.Fa flag 85are constructed by a bitwise-inclusive OR of flags from the following list, 86defined in 87.In fcntl.h : 88.Bl -tag -width indent 89.It Dv AT_REMOVEDIR 90Remove the directory entry specified by 91.Fa fd 92and 93.Fa path 94as a directory, not a normal file. 95.It Dv AT_BENEATH 96Only unlink files and directories which are beneath of the topping 97directory. 98See the description of the 99.Dv O_BENEATH 100flag in the 101.Xr open 2 102manual page. 103.El 104.Pp 105If 106.Fn unlinkat 107is passed the special value 108.Dv AT_FDCWD 109in the 110.Fa fd 111parameter, the current working directory is used and the behavior is 112identical to a call to 113.Fa unlink 114or 115.Fa rmdir 116respectively, depending on whether or not the 117.Dv AT_REMOVEDIR 118bit is set in flag. 119.Pp 120The 121.Fn funlinkat 122system call can be used to unlink an already-opened file, unless that 123file has been replaced since it was opened. 124It is equivalent to 125.Fn unlinkat 126in the case where 127.Fa path 128is already open as the file descriptor 129.Fa fd . 130Otherwise, the path will not be removed and an error will be returned. 131The 132.Fa fd 133can be set the 134.Dv FD_NONE . 135In that case 136.Fn funlinkat 137behaves exactly like 138.Fn unlinkat . 139.Sh RETURN VALUES 140.Rv -std unlink 141.Sh ERRORS 142The 143.Fn unlink 144succeeds unless: 145.Bl -tag -width Er 146.It Bq Er ENOTDIR 147A component of the path prefix is not a directory. 148.It Bq Er EISDIR 149The named file is a directory. 150.It Bq Er ENAMETOOLONG 151A component of a pathname exceeded 255 characters, 152or an entire path name exceeded 1023 characters. 153.It Bq Er ENOENT 154The named file does not exist. 155.It Bq Er EACCES 156Search permission is denied for a component of the path prefix. 157.It Bq Er EACCES 158Write permission is denied on the directory containing the link 159to be removed. 160.It Bq Er ELOOP 161Too many symbolic links were encountered in translating the pathname. 162.It Bq Er EPERM 163The named file is a directory. 164.It Bq Er EPERM 165The named file has its immutable, undeletable or append-only flag set, see the 166.Xr chflags 2 167manual page for more information. 168.It Bq Er EPERM 169The parent directory of the named file has its immutable or append-only flag 170set. 171.It Bq Er EPERM 172The directory containing the file is marked sticky, 173and neither the containing directory nor the file to be removed 174are owned by the effective user ID. 175.It Bq Er EIO 176An I/O error occurred while deleting the directory entry 177or deallocating the inode. 178.It Bq Er EROFS 179The named file resides on a read-only file system. 180.It Bq Er EFAULT 181The 182.Fa path 183argument 184points outside the process's allocated address space. 185.It Bq Er ENOSPC 186On file systems supporting copy-on-write or snapshots, there was not enough 187free space to record metadata for the delete operation of the file. 188.El 189.Pp 190In addition to the errors returned by the 191.Fn unlink , 192the 193.Fn unlinkat 194may fail if: 195.Bl -tag -width Er 196.It Bq Er EBADF 197The 198.Fa path 199argument does not specify an absolute path and the 200.Fa fd 201argument is neither 202.Dv AT_FDCWD 203nor a valid file descriptor open for searching. 204.It Bq Er ENOTEMPTY 205The 206.Fa flag 207parameter has the 208.Dv AT_REMOVEDIR 209bit set and the 210.Fa path 211argument names a directory that is not an empty directory, 212or there are hard links to the directory other than dot or 213a single entry in dot-dot. 214.It Bq Er ENOTDIR 215The 216.Fa flag 217parameter has the 218.Dv AT_REMOVEDIR 219bit set and 220.Fa path 221does not name a directory. 222.It Bq Er EINVAL 223The value of the 224.Fa flag 225argument is not valid. 226.It Bq Er ENOTDIR 227The 228.Fa path 229argument is not an absolute path and 230.Fa fd 231is neither 232.Dv AT_FDCWD 233nor a file descriptor associated with a directory. 234.It Bq Er ENOTCAPABLE 235.Fa path 236is an absolute path, 237or contained a ".." component leading to a 238directory outside of the directory hierarchy specified by 239.Fa fd , 240and the process is in capability mode. 241.It Bq Er ENOTCAPABLE 242The 243.Dv AT_BENEATH 244flag was provided to 245.Fn unlinkat , 246and the absolute 247.Fa path 248does not have its tail fully contained under the topping directory, 249or the relative 250.Fa path 251escapes it. 252.El 253.Pp 254In addition to the errors returned by 255.Fn unlinkat , 256.Fn funlinkat 257may fail if: 258.Bl -tag -width Er 259.It Bq Er EDEADLK 260The file descriptor is not associated with the path. 261.El 262.Sh SEE ALSO 263.Xr chflags 2 , 264.Xr close 2 , 265.Xr link 2 , 266.Xr rmdir 2 , 267.Xr symlink 7 268.Sh STANDARDS 269The 270.Fn unlinkat 271system call follows The Open Group Extended API Set 2 specification. 272.Sh HISTORY 273The 274.Fn unlink 275function appeared in 276.At v1 . 277The 278.Fn unlinkat 279system call appeared in 280.Fx 8.0 . 281The 282.Fn funlinkat 283system call appeared in 284.Fx 13.0 . 285.Pp 286The 287.Fn unlink 288system call traditionally allows the super-user to unlink directories which 289can damage the file system integrity. 290This implementation no longer permits it. 291