已经是用sudo 执行的啊，而且这个安装程序也知道是要安装成system-wide，我本想直接用程序安装到这个位置，这样firefox可以和opera共享这个插件，但不料提示这样的错误。lisir@ubuntu:~/OperaDownloads/install_flash_player_9_linux$ sudo ./flashplayer-installer
Password:
Copyright(C) 2002-2006 Adobe Macromedia Software LLC. All rights reserved.
Adobe Flash Player 9 for Linux
Adobe Flash Player 9 will be installed on this machine.
You are running the Adobe Flash Player installer as the "root" user.
Adobe Flash Player 9 will be installed system-wide.
……
To install Adobe Flash Player 9 now, press ENTER.
To cancel the installation at any time, press Control-C.
NOTE: Please exit any browsers you may have running.
Press ENTER to continue...
Please enter the installation path of the Mozilla, SeaMonkey,
or Firefox browser (i.e., /usr/lib/mozilla): /usr/lib/mozilla
dir= /usr/lib/mozilla
WARNING: Please enter a valid installation path.
Please enter the installation path of the Mozilla, SeaMonkey,
or Firefox browser (i.e., /usr/lib/mozilla): /usr/lib/mozilla/plugins/
dir= /usr/lib/mozilla/plugins/
WARNING: Please enter a valid installation path.
……
当然虽然不明白为何产生这个问题，但flash插件还是安装上了，我是先安装在家目录下，再拷过去的。
我真傻，不用sudo就可以了，它会自动默认安装到家目录下的.mozilla目录下。