编辑 /etc/fonts/conf.d 下面的 49-sansserif.conf 文件
sudo gedit /etc/fonts/conf.d/49-sansserif.conf
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!--
If the font still has no generic name, add sans-serif
-->
<match target="pattern">
<test qual="all" name="family" compare="not_eq">
<string>sans-serif</string>
</test>
<test qual="all" name="family" compare="not_eq">
<string>serif</string>
</test>
<test qual="all" name="family" compare="not_eq">
<string>monospace</string>
</test>
<edit name="family" mode="append_last">
<string>sans-serif</string> //把sans-serif改成sans就可以了
</edit>
</match>
</fontconfig>
把红色粗体中的sans-serif改成sans就可以了