.Dt UNLINK 2
.Os BSD 4
.Sh NAME
-.Nm unlink
+.Nm unlink ,
+.Nm unlinkat
.Nd remove directory entry
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
-.Fn unlink "const char *path"
+.Fo unlink
+.Fa "const char *path"
+.Fc
+.Ft int
+.Fn unlinkat "int fd" "const char *path" "int flag"
.Sh DESCRIPTION
The
.Fn unlink
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.
+.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
Upon successful completion, a value of 0 is returned.
Otherwise, a value of -1 is returned and
.Sh ERRORS
The
.Fn unlink
-succeeds unless:
+system call will fail if:
.Bl -tag -width Er
-.It Bq Er ENOTDIR
-A component of the path prefix is not a directory.
-.It Bq Er ENAMETOOLONG
-A component of a pathname exceeded
-.Dv {NAME_MAX}
-characters, or an entire path name exceeded
-.Dv {PATH_MAX}
-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 EBUSY
+The entry to be unlinked is the mount point for a
+mounted file system.
+.\" ===========
+.It Bq Er EBUSY
+The file named by the
+.Fa path
+argument cannot be unlinked
+because it is being used by the system or by another process.
+.\" ===========
+.It Bq Er EFAULT
+.Fa Path
+points outside the process's allocated address space.
+.\" ===========
+.It Bq Er EIO
+An I/O error occurs while deleting the directory entry
+or deallocating the inode.
+.\" ===========
.It Bq Er ELOOP
-Too many symbolic links were encountered in translating the pathname.
+Too many symbolic links are encountered in translating the pathname.
+This is taken to be indicative of a looping symbolic link.
+.\" ===========
+.It Bq Er ENAMETOOLONG
+A component of a pathname exceeds
+.Dv {NAME_MAX}
+characters, or an entire path name exceeds
+.Dv {PATH_MAX}
+characters (possibly as a result of expanding a symlink).
+.\" ===========
+.It Bq Er ENOENT
+The named file does not exist.
+.\" ===========
+.It Bq Er ENOTDIR
+A component of the path prefix is not a directory.
+.\" ===========
.It Bq Er EPERM
The named file is a directory and the effective user ID
of the process is not the super-user.
+.\" ===========
.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 EBUSY
-The entry to be unlinked is the mount point for a
-mounted file system.
-.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
-.Fa Path
-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 close 2 ,
.Xr link 2 ,
-.Xr rmdir 2
+.Xr rmdir 2 ,
.Xr symlink 7
+.Sh STANDARDS
+The
+.Fn unlinkat
+system call is expected to conform to POSIX.1-2008 .
.Sh HISTORY
An
.Fn unlink
function call appeared in
.At v6 .
+The
+.Fn unlinkat
+system call appeared in OS X 10.10
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