图形界面
安装dconf-editor
sudo apt-get install dconf-editor
打开dconf-editor，进入org -> gnome -> gnome-screenshot，修改auto-save-directory值为 file:///home/yeshaoting/Pictures/screenshot/。
命令行
gsettings set org.gnome.gnome-screenshot auto-save-directory “file:///home/yeshaoting/Pictures/screenshot/“