1·Effects: Unlinks the node from the circular list.
作用：从循环链表断开该节点的链接。
2·KEYCTL_UNLINK unlinks a key or keyring from another keyring.
KEYCTL_UNLINK将密钥或keyring与另一个keyring的链接取消。
3·Effects: Unlinks the leftmost node from the tree, and updates the header link to the new leftmost node.
作用：断开树的最左节点的链接并将头节点链接到新的最左节点。
4·The second was that, when unlinking a directory, pseudo helpfully unlinks the contents of that directory.
第二个选择是，在断开目录链接时，pseudo 可以帮助断开该目录的内容的链接。
5·This code carefully unlinks the temporary file, leaving it open but already removed, to clean up automatically.
此代码小心地断开与临时文件的链接(让它仍是打开的，但已经被删除)来进行自动清空。