|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 parameter, the current working directory is used for the respective name argument. 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.
.Rv -std link
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 characters, 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 permission. [EACCES] The requested link requires writing in a directory with a mode that denies write permission. [ELOOP] Too many symbolic links were encountered in translating 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 directory. [EDQUOT] The directory in which the entry for the new link is being placed cannot be extended because the users 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 processs 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 absolute 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.
The link system call is expected to conform to -p1003.1-90. The linkat system call follows The Open Group Extended API Set 2 specification.
The link function appeared in AT&T v7 . The linkat system call appeared in
.Fx 8.0 .
The link system call traditionally allows the super-user to link directories which corrupts the file system coherency. This implementation no longer permits it.