First, introduce how to embed pdf in Hexo.
npm install –save hexo-pdf
Second, enable pdf in the Next theme
Open the file of the next/_config.yml and edit false to true, as shown in the attached picture.
Third, embed pdf links (eg. Linux 就该这么学)
Fat and ntfs partion wont support file permissions
https://askubuntu.com/questions/152607/cant-make-a-file-executable