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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.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 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 June 4, 1993
.Dt UNLINK 2
.Os BSD 4
.Sh NAME
.Nm unlink
.Nd remove directory entry
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn unlink "const char *path"
.Sh DESCRIPTION
The
.Fn unlink
function
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.
.Fa path
may not be a directory.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn unlink
succeeds unless:
.Bl -tag -width ENAMETOOLONGAA
.It Bq Er ENOTDIR
A component of the path prefix is not 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 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
.Sh SEE ALSO
.Xr close 2 ,
.Xr link 2 ,
.Xr rmdir 2 ,
.Xr symlink 7
.Sh HISTORY
An
.Fn unlink
function call appeared in
.At v6 .
.Pp
The
.Fn unlink
system call traditionally allows the super-user to unlink directories which
can damage the filesystem integrity. This implementation no longer permits
it.
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