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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.Dd February 23, 2021 29.Dt UNLINK 2 30.Os 31.Sh NAME 32.Nm unlink , 33.Nm unlinkat , 34.Nm funlinkat 35.Nd remove directory entry 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft int 41.Fn unlink "const char *path" 42.Ft int 43.Fn unlinkat "int dfd" "const char *path" "int flag" 44.Ft int 45.Fn funlinkat "int dfd" "const char *path" "int fd" "int flag" 46.Sh DESCRIPTION 47The 48.Fn unlink 49system call 50removes the link named by 51.Fa path 52from its directory and decrements the link count of the 53file which was referenced by the link. 54If that decrement reduces the link count of the file 55to zero, 56and no process has the file open, then 57all resources associated with the file are reclaimed. 58If one or more process have the file open when the last link is removed, 59the link is removed, but the removal of the file is delayed until 60all references to it have been closed. 61The 62.Fa path 63argument 64may not be a directory. 65.Pp 66The 67.Fn unlinkat 68system call is equivalent to 69.Fn unlink 70or 71.Fn rmdir 72except in the case where 73.Fa path 74specifies a relative path. 75In this case the directory entry to be removed is determined 76relative to the directory associated with the file descriptor 77.Fa dfd 78instead of the current working directory. 79.Pp 80The values for 81.Fa flag 82are constructed by a bitwise-inclusive OR of flags from the following list, 83defined in 84.In fcntl.h : 85.Bl -tag -width indent 86.It Dv AT_REMOVEDIR 87Remove the directory entry specified by 88.Fa fd 89and 90.Fa path 91as a directory, not a normal file. 92.It Dv AT_RESOLVE_BENEATH 93Only walk paths below the directory specified by the 94.Ar fd 95descriptor. 96See the description of the 97.Dv O_RESOLVE_BENEATH 98flag in the 99.Xr open 2 100manual page. 101.El 102.Pp 103If 104.Fn unlinkat 105is passed the special value 106.Dv AT_FDCWD 107in the 108.Fa fd 109parameter, the current working directory is used and the behavior is 110identical to a call to 111.Fa unlink 112or 113.Fa rmdir 114respectively, depending on whether or not the 115.Dv AT_REMOVEDIR 116bit is set in flag. 117.Pp 118The 119.Fn funlinkat 120system call can be used to unlink an already-opened file, unless that 121file has been replaced since it was opened. 122It is equivalent to 123.Fn unlinkat 124in the case where 125.Fa path 126is already open as the file descriptor 127.Fa fd . 128Otherwise, the path will not be removed and an error will be returned. 129The 130.Fa fd 131can be set the 132.Dv FD_NONE . 133In that case 134.Fn funlinkat 135behaves exactly like 136.Fn unlinkat . 137.Sh RETURN VALUES 138.Rv -std unlink 139.Sh ERRORS 140The 141.Fn unlink 142succeeds unless: 143.Bl -tag -width Er 144.It Bq Er ENOTDIR 145A component of the path prefix is not a directory. 146.It Bq Er EISDIR 147The named file is a directory. 148.It Bq Er ENAMETOOLONG 149A component of a pathname exceeded 255 characters, 150or an entire path name exceeded 1023 characters. 151.It Bq Er ENOENT 152The named file does not exist. 153.It Bq Er EACCES 154Search permission is denied for a component of the path prefix. 155.It Bq Er EACCES 156Write permission is denied on the directory containing the link 157to be removed. 158.It Bq Er ELOOP 159Too many symbolic links were encountered in translating the pathname. 160.It Bq Er EPERM 161The named file is a directory. 162.It Bq Er EPERM 163The named file has its immutable, undeletable or append-only flag set, see the 164.Xr chflags 2 165manual page for more information. 166.It Bq Er EPERM 167The parent directory of the named file has its immutable or append-only flag 168set. 169.It Bq Er EPERM 170The directory containing the file is marked sticky, 171and neither the containing directory nor the file to be removed 172are owned by the effective user ID. 173.It Bq Er EIO 174An I/O error occurred while deleting the directory entry 175or deallocating the inode. 176.It Bq Er EINTEGRITY 177Corrupted data was detected while reading from the file system. 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 or the 241.Dv AT_RESOLVE_BENEATH 242flag was specified. 243.El 244.Pp 245In addition to the errors returned by 246.Fn unlinkat , 247.Fn funlinkat 248may fail if: 249.Bl -tag -width Er 250.It Bq Er EDEADLK 251The file descriptor is not associated with the path. 252.El 253.Sh SEE ALSO 254.Xr chflags 2 , 255.Xr close 2 , 256.Xr link 2 , 257.Xr rmdir 2 , 258.Xr symlink 7 259.Sh STANDARDS 260The 261.Fn unlinkat 262system call follows The Open Group Extended API Set 2 specification. 263.Sh HISTORY 264The 265.Fn unlink 266function appeared in 267.At v1 . 268The 269.Fn unlinkat 270system call appeared in 271.Fx 8.0 . 272The 273.Fn funlinkat 274system call appeared in 275.Fx 13.0 . 276.Pp 277The 278.Fn unlink 279system call traditionally allows the super-user to unlink directories which 280can damage the file system integrity. 281This implementation no longer permits it. 282