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.\"     @(#)link.2	8.3 (Berkeley) 1/12/94
.\"
.Dd $Mdocdate: November 21 2008 $
.Dt LINK 2
.Os
.Sh NAME
.Nm link
.Nd make hard link to a file
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn link "const char *name1" "const char *name2"
.Sh DESCRIPTION
The
.Fn link
function atomically creates the specified directory entry (hard link)
.Fa name2
with the attributes of the underlying object pointed at by
.Fa name1 .
If the link is successful: the link count of the underlying object
is incremented;
.Fa name1
and
.Fa name2
share equal access and rights to the underlying object.
.Pp
If
.Fa name1
is removed, the file
.Fa name2
is not deleted and the link count of the underlying object is decremented.
.Pp
.Fa name1
must exist for the hard link to succeed and both
.Fa name1
and
.Fa name2
must be in the same file system.
As mandated by POSIX.1
.Fa name1
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
.Fn link
will fail and no link will be created if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of either 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
A component of either path prefix does not exist.
.It Bq Er EOPNOTSUPP
The file system containing the file named by
.Fa name1
does not support links.
.It Bq Er EMLINK
The link count of the file named by
.Fa name1
would exceed
.Dv LINK_MAX .
.It Bq Er EACCES
A component of either path prefix denies search permission.
.It Bq Er EACCES
The requested link requires writing in a directory with a mode
that denies write permission.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating one of the pathnames.
.It Bq Er ENOENT
The file named by
.Fa name1
does not exist.
.It Bq Er EEXIST
The link named by
.Fa name2
does exist.
.It Bq Er EPERM
The file named by
.Fa name1
is a directory and the effective
user ID is not superuser,
or the file system containing the file does not permit the use of
.Fn link
on a directory.
.It Bq Er EPERM
The file named by
.Fa name1
is flagged immutable or append-only.
.It Bq Er EXDEV
The link named by
.Fa name2
and the file named by
.Fa name1
are on different file systems.
.It Bq Er ENOSPC
The directory in which the entry for the new link is being placed
cannot be extended because there is no space left on the file
system containing the directory.
.It Bq Er EDQUOT
The directory in which the entry for the new link
is being placed cannot be extended because the
user's quota of disk blocks on the file system
containing the directory has been exhausted.
.It Bq Er EIO
An I/O error occurred while reading from or writing to
the file system to make the directory entry.
.It Bq Er EROFS
The requested link requires writing in a directory on a read-only file
system.
.It Bq Er EFAULT
One of the pathnames specified
is outside the process's allocated address space.
.El
.Sh SEE ALSO
.Xr ln 1 ,
.Xr readlink 2 ,
.Xr symlink 2 ,
.Xr unlink 2
.Sh STANDARDS
The
.Fn link
function is expected to conform to
.St -p1003.1-88 .