用vlock 的師兄

咩係 vlock 呢？ 在Linux 有這樣的描述：

Virtual Console locking program

vlock either locks the current terminal (which may be any kind of terminal, local or remote), or locks the entire virtual console system, completely disabling all console access. vlock gives up these locks when either the password of the user who started vlock or the root password is typed.

我記得係七八年前,我遇見了一位師兄用vlock，他知道vlock 安全一點要加用-a。 用了"-a" 係完全封銷起來,不能轉到其他虛擬的console 。但我走到他的機器前, 還可以按 Ctrl-F1, Ctrl-F2 .... 轉換console..... 你地估下點解？