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unlink.2 revision 1.25 
 $NetBSD: unlink.2,v 1.25 2012/12/01 20:45:01 wiz Exp $

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 @(#)unlink.2 8.1 (Berkeley) 6/4/93

.Dd April 3, 2010
.Dt UNLINK 2
.Os
.Sh NAME
.Nm unlink ,
.Nm unlinkat ,
.Nd remove directory entry
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
n unistd.h .Ft int
.Fn unlink "const char *path"
n fcntl.h .Ft int
.Fn unlinkat "int fd" "const char *path" "int flag"
.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.

p
.Fn unlinkat
works the same way as
.Fn unlink
except if
.Fa path
is relative. In that case, it is looked up from a directory whose file
descriptor was passed as
.Fa fd .
Search permission is required on
.Fa fd
except if that file descriptor was open with
.Dv O_SEARCH
option.
.Fa fd
can be set to
.Dv AT_FDCWD
in order to specify current directory.

p
.Fn unlinkat
will remove directories just like
.Fn rmdir
provided
.Dv AT_REMOVEDIR
is set in
.Fa flag .
.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:
l -tag -width Er t Bq Er EACCES Search permission is denied for a component of the path prefix, or
write permission is denied on the directory containing the link
to be removed.
t Bq Er EBUSY The entry to be unlinked is the mount point for a
mounted file system.
t Bq Er EFAULT .Fa path
points outside the process's allocated address space.
t Bq Er EIO An I/O error occurred while deleting the directory entry
or deallocating the inode.
t Bq Er ELOOP Too many symbolic links were encountered in translating the pathname.
t Bq Er ENAMETOOLONG A component of a pathname exceeded
rq Dv NAME_MAX characters, or an entire path name exceeded
rq Dv PATH_MAX characters.
t Bq Er ENOENT The named file does not exist.
t Bq Er ENOTDIR A component of the path prefix is not a directory.
t Bq Er EPERM The named file is a directory and the effective user ID
of the process is not the super-user, the file system
containing the file does not permit the use of
.Fn unlink
on a directory,
or 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.
t Bq Er EROFS The named file resides on a read-only file system.
.El
.Sh SEE ALSO
.Xr close 2 ,
.Xr link 2 ,
.Xr rmdir 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn unlink
function conforms to
.St -p1003.1-90 .
.Fn unlinkat
conforms to
.St -p1003.1-2008 .
.Sh HISTORY
An
.Fn unlink
function call appeared in
.At v2 .