在Ubuntu下经常用putty，老是为这个复制粘贴的事情搞得很郁闷，今天有空，网上搜了一下，原来gnome还有这种贴心的功能：
Linux users:
In Gnome,
you can paste text without previously copying it to the clipboard.
How does this work? First, highlight a chunk of text in any application,
then open a new application and middle-click the mouse. The highlighted text will automatically get pasted into the active application -- bypassing the clipboard altogether! In fact,
this method will not disturb the existing contents of the clipboard in any way.
This method works fine for Putty on Linux.