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LINK(2)			  FreeBSD System Calls Manual		       LINK(2)

NAME
     link, linkat -- make a hard file link

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     link(const	char *name1, const char	*name2);

     int
     linkat(int	fd1, const char	*name1,	int fd2, const char *name2, int	flag);

DESCRIPTION
     The link()	system call atomically creates the specified directory entry
     (hard link) name2 with the	attributes of the underlying object pointed at
     by	name1.	If the link is successful: the link count of the underlying
     object is incremented; name1 and name2 share equal	access and rights to
     the underlying object.

     If	name1 is removed, the file name2 is not	deleted	and the	link count of
     the underlying object is decremented.

     The object	pointed	at by the name1	argument must exist for	the hard link
     to	succeed	and both name1 and name2 must be in the	same file system.  The
     name1 argument may	not be a directory.

     The linkat() system call is equivalent to link except in the case where
     either name1 or name2 or both are relative	paths.	In this	case a rela-
     tive path name1 is	interpreted relative to	the directory associated with
     the file descriptor fd1 instead of	the current working directory and sim-
     ilarly for	name2 and the file descriptor fd2.

     Values for	flag are constructed by	a bitwise-inclusive OR of flags	from
     the following list, defined in <fcntl.h>:

     AT_SYMLINK_FOLLOW
	     If	name1 names a symbolic link, a new link	for the	target of the
	     symbolic link is created.

     If	linkat() is passed the special value AT_FDCWD in the fd1 or fd2	param-
     eter, the current working directory is used for the respective name argu-
     ment.  If both fd1	and fd2	have value AT_FDCWD, the behavior is identical
     to	a call to link().  Unless flag contains	the AT_SYMLINK_FOLLOW flag, if
     name1 names a symbolic link, a new	link is	created	for the	symbolic link
     name1 and not its target.

RETURN VALUES
     The link()	function returns the value 0 if	successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The link()	system call will fail and no link will be created if:

     [ENOTDIR]		A component of either path prefix is not a directory.

     [ENAMETOOLONG]	A component of either pathname exceeded	255 charac-
			ters, or entire	length of either path name exceeded
			1023 characters.

     [ENOENT]		A component of either path prefix does not exist.

     [EOPNOTSUPP]	The file system	containing the file named by name1
			does not support links.

     [EMLINK]		The link count of the file named by name1 would	exceed
			32767.

     [EACCES]		A component of either path prefix denies search	per-
			mission.

     [EACCES]		The requested link requires writing in a directory
			with a mode that denies	write permission.

     [ELOOP]		Too many symbolic links	were encountered in translat-
			ing one	of the pathnames.

     [ENOENT]		The file named by name1	does not exist.

     [EEXIST]		The link named by name2	does exist.

     [EPERM]		The file named by name1	is a directory.

     [EPERM]		The file named by name1	has its	immutable or append-
			only flag set, see the chflags(2) manual page for more
			information.

     [EPERM]		The parent directory of	the file named by name2	has
			its immutable flag set.

     [EXDEV]		The link named by name2	and the	file named by name1
			are on different file systems.

     [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 direc-
			tory.

     [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.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system	to make	the directory entry.

     [EROFS]		The requested link requires writing in a directory on
			a read-only file system.

     [EFAULT]		One of the pathnames specified is outside the
			process's allocated address space.

     In	addition to the	errors returned	by the link(), the linkat() system
     call may fail if:

     [EBADF]		The name1 or name2 argument does not specify an	abso-
			lute path and the fd1 or fd2 argument, respectively,
			is neither AT_FDCWD nor	a valid	file descriptor	open
			for searching.

     [EINVAL]		The value of the flag argument is not valid.

     [ENOTDIR]		The name1 or name2 argument is not an absolute path
			and fd1	or fd2,	respectively, is neither AT_FDCWD nor
			a file descriptor associated with a directory.

SEE ALSO
     chflags(2), readlink(2), symlink(2), unlink(2)

STANDARDS
     The link()	system call is expected	to conform to ISO/IEC 9945-1:1990
     (``POSIX.1'').  The linkat() system call follows The Open Group Extended
     API Set 2 specification.

HISTORY
     The link()	function appeared in Version 7 AT&T UNIX.  The linkat()	system
     call appeared in FreeBSD 8.0.

     The link()	system call traditionally allows the super-user	to link	direc-
     tories which corrupts the file system coherency.  This implementation no
     longer permits it.

FreeBSD	9.3			April 10, 2008			   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY

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