用root身份将主文件夹下的.bashrc复制到/tmp下 并更名为bashrc : cp /.bashrc   /tmp/bashrc

复制/var/log/wtmp到当前目录 cp  /var/log/wtmp  .

复制/etc/下所有文件到/tmp下  cp -r /etc/ /tmp

创建（1）中的软链接bashrc_  cp  -l  bashrc bashrc_

若~/.bashrc 比 /tmp/bahsrc新则复制过来 cp -u ~/.bashrc /tmp/bashrc