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link() - Unix, Linux System Call
link - make a new name for a file
int link(const char *oldpath, const char *newpath);
link() creates a new link (also known as a hard link) to an existing file.
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
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
Write access to the directory containing
newpath is denied, or search permission is denied for one of the directories
in the path prefix of
newpath. (See also
newpath already exists.
oldpath or newpath points outside your accessible address space. |
An I/O error occurred.
Too many symbolic links were encountered in resolving
oldpath or newpath. |
The file referred to by
oldpath already has the maximum number of links to it.
oldpath or newpath was too long. |
A directory component in
oldpath or newpath does not exist or is a dangling symbolic link.
Insufficient kernel memory was available.
The device containing the file has no room for the new directory
A component used as a directory in
oldpath or newpath is not, in fact, a directory.
oldpath is a directory.
The filesystem containing
oldpath and newpath does not support the creation of hard links.
The file is on a read-only filesystem.
oldpath and newpath are not on the same mounted filesystem.
(Linux permits a filesystem to be mounted at multiple points, but
does not work across different mount points,
even if the same filesystem is mounted on both.)
Hard links, as created by
link(), cannot span filesystems. Use
symlink() if this is required.
POSIX.1-2001 says that
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
newpath becomes a symbolic link to the same file that
oldpath refers to).
Some other implementations behave in the same manner as Linux.
SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).
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
to find out if the link got created.