NAME
link - make a new name for a file
SYNOPSIS
#include <unistd.h>
I int link(const char * oldpath , const char * newpath );
DESCRIPTION
R link ()
creates a new link (also known as a hard link) to an existing file.
If
newpath
exists it will
not
be overwritten.
This new name may be used exactly as the old one for any operation;
both names refer to the same file (and so have the same permissions
and ownership) and it is impossible to tell which name was the
\`original'.
RETURN VALUE
On success, zero is returned.
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
EACCES
Write access to the directory containing
newpath
is denied, or search permission is denied for one of the directories
in the path prefix of
oldpath
or
R newpath .
(See also
path_resolution(7).)
EEXIST
newpath
already exists.
EFAULT
R oldpath or newpath points outside your accessible address space.
EIO
An I/O error occurred.
ELOOP
Too many symbolic links were encountered in resolving
R oldpath or newpath .
EMLINK
The file referred to by
oldpath
already has the maximum number of links to it.
ENAMETOOLONG
R oldpath or newpath was too long.
ENOENT
A directory component in
R oldpath or newpath
does not exist or is a dangling symbolic link.
ENOMEM
Insufficient kernel memory was available.
ENOSPC
The device containing the file has no room for the new directory
entry.
ENOTDIR
A component used as a directory in
R oldpath or newpath
is not, in fact, a directory.
EPERM
oldpath
is a directory.
EPERM
The filesystem containing
R oldpath and newpath
does not support the creation of hard links.
EROFS
The file is on a read-only filesystem.
EXDEV
R oldpath and newpath
are not on the same mounted filesystem.
(Linux permits a filesystem to be mounted at multiple points, but
link(2)
does not work across different mount points,
even if the same filesystem is mounted on both.)
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).
NOTES
Hard links, as created by
R link (),
cannot span filesystems.
Use
symlink(2)
if this is required.
POSIX.1-2001 says that
R link ()
should dereference
oldpath
if it is a symbolic link.
However, Linux does not do so: if
oldpath
is a symbolic link, then
newpath
is created as a (hard) link to the same symbolic link file
(i.e.,
newpath
becomes a symbolic link to the same file that
oldpath
refers to).
Some other implementations behave in the same manner as Linux.
BUGS
On NFS file systems, the return code may be wrong in case the NFS server
performs the link creation and dies before it can say so.
Use
stat(2)
to find out if the link got created.
SEE ALSO
ČLÁNKY DO MAILU