link - make a new name for a file
- include <unistd.h>
int link(const char *oldpath, const char *newpath);
link(2) 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.
- oldpath and newpath are not on the same filesystem.
- The filesystem containing oldpath and newpath does not support the creation of hard links.
- oldpath or newpath points outside your accessible address space.
- Write access to the directory containing newpath is not allowed for the process's effective uid, or one of the directories in oldpath or newpath did not allow search (execute) permission.
- oldpath or newpath was too long.
- A directory component in oldpath or newpath does not exist or is a dangling symbolic link.
- A component used as a directory in oldpath or newpath is not, in fact, a directory.
- Insufficient kernel memory was available.
- The file is on a read-only filesystem.
- newpath already exists.
- The file referred to by oldpath already has the maximum number of links to it.
- Too many symbolic links were encountered in resolving oldpath or newpath.
- The device containing the file has no room for the new directory entry.
- oldpath is a directory.
- An I/O error occurred.
Hard links, as created by link(2), cannot span filesystems. Use symlink(2) if this is required.
SVr4, SVID, POSIX, BSD 4.3, X/OPEN. SVr4 documents additional ENOLINK and EMULTIHOP error conditions; POSIX.1 does not document ELOOP. X/OPEN does not document EFAULT, ENOMEM or EIO.
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.
symlink(2), unlink(2), rename(2), open(2), stat(2), ln(1)