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+.\" 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.
+.\" 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
+.\" $FreeBSD$
+.\"
+.Dd April 25, 2010
+.Dt UNLINK 2
+.Os
+.Sh NAME
+.Nm unlink ,
+.Nm unlinkat
+.Nd remove directory entry
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In unistd.h
+.Ft int
+.Fn unlink "const char *path"
+.Ft int
+.Fn unlinkat "int fd" "const char *path" "int flag"
+.Sh DESCRIPTION
+The
+.Fn unlink
+system call
+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.
+The
+.Fa path
+argument
+may not be a directory.
+.Pp
+The
+.Fn unlinkat
+system call is equivalent to
+.Fn unlink
+or
+.Fn rmdir
+except in the case where
+.Fa path
+specifies a relative path.
+In this case the directory entry to be removed is determined
+relative to the directory associated with the file descriptor
+.Fa fd
+instead of the current working directory.
+.Pp
+The values for
+.Fa flag
+are constructed by a bitwise-inclusive OR of flags from the following list,
+defined in
+.In fcntl.h :
+.Bl -tag -width indent
+.It Dv AT_REMOVEDIR
+Remove the directory entry specified by
+.Fa fd
+and
+.Fa path
+as a directory, not a normal file.
+.El
+.Pp
+If
+.Fn unlinkat
+is passed the special value
+.Dv AT_FDCWD
+in the
+.Fa fd
+parameter, the current working directory is used and the behavior is
+identical to a call to
+.Fa unlink
+or
+.Fa rmdir
+respectively, depending on whether or not the
+.Dv AT_REMOVEDIR
+bit is set in flag.
+.Sh RETURN VALUES
+.Rv -std unlink
+.Sh ERRORS
+The
+.Fn unlink
+succeeds unless:
+.Bl -tag -width Er
+.It Bq Er ENOTDIR
+A component of the path prefix is not a directory.
+.It Bq Er EISDIR
+The named file is a directory.
+.It Bq Er ENAMETOOLONG
+A component of a pathname exceeded 255 characters,
+or an entire path name exceeded 1023 characters.
+.It Bq Er ENOENT
+The named file does not exist.
+.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 ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.It Bq Er EPERM
+The named file is a directory.
+.It Bq Er EPERM
+The named file has its immutable, undeletable or append-only flag set, see the
+.Xr chflags 2
+manual page for more information.
+.It Bq Er EPERM
+The parent directory of the named file has its immutable or append-only flag
+set.
+.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 EIO
+An I/O error occurred while deleting the directory entry
+or deallocating the inode.
+.It Bq Er EROFS
+The named file resides on a read-only file system.
+.It Bq Er EFAULT
+The
+.Fa path
+argument
+points outside the process's allocated address space.
+.El
+.Pp
+In addition to the errors returned by the
+.Fn unlink ,
+the
+.Fn unlinkat
+may fail if
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa path
+argument does not specify an absolute path and the
+.Fa fd
+argument is neither
+.Dv AT_FDCWD
+nor a valid file descriptor open for searching.
+.It Bq Er ENOTEMPTY
+The
+.Fa flag
+parameter has the
+.Dv AT_REMOVEDIR
+bit set and the
+.Fa path
+argument names a directory that is not an empty directory,
+or there are hard links to the directory other than dot or
+a single entry in dot-dot.
+.It Bq Er ENOTDIR
+The
+.Fa flag
+parameter has the
+.Dv AT_REMOVEDIR
+bit set and
+.Fa path
+does not name a directory.
+.It Bq Er EINVAL
+The value of the
+.Fa flag
+argument is not valid.
+.It Bq Er ENOTDIR
+The
+.Fa path
+argument is not an absolute path and
+.Fa fd
+is neither
+.Dv AT_FDCWD
+nor a file descriptor associated with a directory.
+.El
+.Sh SEE ALSO
+.Xr chflags 2 ,
+.Xr close 2 ,
+.Xr link 2 ,
+.Xr rmdir 2 ,
+.Xr symlink 7
+.Sh STANDARDS
+The
+.Fn unlinkat
+system call follows The Open Group Extended API Set 2 specification.
+.Sh HISTORY
+The
+.Fn unlink
+function appeared in
+.At v6 .
+The
+.Fn unlinkat
+system call appeared in
+.Fx 8.0 .
+.Pp
+The
+.Fn unlink
+system call traditionally allows the super-user to unlink directories which
+can damage the file system integrity.
+This implementation no longer permits it.