commandline和GUI下的clipboard的交互
Mac下
echo $PATH | pbcopy，copy to clipboard
echo "$(pbpaste -Prefer text)"，copy from clipboard
Linux下，首先需要安裝xsel
echo $PATH | xsel --clipboard，copy to clipboard
echo "$(xsel --output --clipboard)"，copy from clipboard
Windows下，clip是需要另外安裝的外部程序
set %path% | clip
Cygwin下
echo $PATH | putclip，copy to clipboard
echo "$(getclip)"，copy from clipboard
