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NAME
link - make a new name for a file
SYNOPSIS
#include <unistd.h>
int link(const char *oldpath, const char *newpath);
DESCRIPTION
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’.
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 newpath. (See also path_resolu
tion(7).)
EEXIST newpath already exists.
EFAULT oldpath or newpath points outside your accessible address space.
EIO An I/O error occurred.
ELOOP Too many symbolic links were encountered in resolving oldpath or
newpath.
EMLINK The file referred to by oldpath already has the maximum number
of links to it.
ENAMETOOLONG
oldpath or newpath was too long.
ENOENT A directory component in 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 oldpath or newpath is not, in
fact, a directory.
EPERM oldpath is a directory.
EPERM The filesystem containing oldpath and newpath does not support
the creation of hard links.
EROFS The file is on a read-only filesystem.
EXDEV 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.)
SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).
NOTES
Hard links, as created by link(), cannot span filesystems. Use sym
link(2) 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 (i.e., newpath becomes a symbolic link to the same file that
oldpath refers to). Some other implementations behave in the same man‐
ner 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.
ln(1), linkat(2), open(2), rename(2), stat(2), symlink(2), unlink(2)
path_resolution(7)