Unknown option 'francais'我通过安装缺少的语言包解决了该问题：
sudo apt-get install texlive-lang-european
现在，遇到问题Unknown language 'french'，详细错误信息如下：
! Package babel Error: Unknown language `french'. Either you have
(babel) misspelled its name, it has not been installed,
(babel) or you requested it in a previous run. Fix its name,
(babel) install it or just rerun the file, respectively.
答案1
是texlive-lang-european一组欧洲语言，其中没有法语；
sudo apt-get install texlive-lang-french
看https://packages.debian.org/stable/tex/texlive-lang-french和https://packages.debian.org/stable/tex/texlive-lang-european了解有关软件包的详细信息。